KSH(1)                           User commands                          KSH(1)



NAME
       ksh - Public domain Korn shell

SYNOPSIS
       ksh [±abCefhikmnprsuvxX] [±o option] [ [ -c command-string [command-
       name] | -s | file ] [argument ...] ]

DESCRIPTION
       ksh is a command interpreter that is intended for both interactive  and
       shell  script  use.   Its  command  language is a superset of the sh(1)
       shell language.

   Shell Startup
       The following options can be specified only on the command line:

       -c command-string
              the shell executes the command(s) contained in command-string

       -i     interactive mode -- see below

       -l     login shell -- see below interactive mode -- see below

       -s     the shell reads commands from  standard  input;  all  non-option
              arguments are positional parameters

       -r     restricted mode -- see below

       In  addition  to  the  above, the options described in the set built-in
       command can also be used on the command line.

       If neither the -c nor the -s options  are  specified,  the  first  non-
       option  argument  specifies the name of a file the shell reads commands
       from; if there are no non-option arguments, the  shell  reads  commands
       from  standard input.  The name of the shell (i.e., the contents of the
       $0) parameter is determined as follows: if the -c option  is  used  and
       there is a non-option argument, it is used as the name; if commands are
       being read from a file, the file is used as  the  name;  otherwise  the
       name the shell was called with (i.e., argv[0]) is used.

       A  shell  is  interactive  if the -i option is used or if both standard
       input and standard error are attached to a tty.  An  interactive  shell
       has  job control enabled (if available), ignores the INT, QUIT and TERM
       signals, and prints prompts before  reading  input  (see  PS1  and  PS2
       parameters).   For non-interactive shells, the trackall option is on by
       default (see set command below).

       A shell is restricted if the -r option is used or if either  the  base-
       name of the name the shell is invoked with or the SHELL parameter match
       the pattern *r*sh (e.g.,  rsh,  rksh,  rpdksh,  etc.).   The  following
       restrictions come into effect after the shell processes any profile and
       $ENV files:
         ·    the cd command is disabled
         ·    the SHELL, ENV and PATH parameters can't be changed
         ·    command names can't be specified with absolute or relative paths
         ·    the -p option of the command built-in can't be used
         ·    redirections  that  create files can't be used (i.e., >, >|, >>,
              <>)

       A shell is privileged if the -p option is used or if the  real  user-id
       or  group-id  does  not  match  the  effective user-id or group-id (see
       getuid(2), getgid(2)).  A privileged shell does not process $HOME/.pro-
       file nor the ENV parameter (see below), instead the file /etc/suid_pro-
       file is processed.  Clearing the privileged option causes the shell  to
       set its effective user-id (group-id) to its real user-id (group-id).

       If  the  basename  of the name the shell is called with (i.e., argv[0])
       starts with - or if the -l option is used, the shell is assumed to be a
       login  shell and the shell reads and executes the contents of /etc/pro-
       file, $HOME/.profile and $ENV if they exist and are readable.

       If the ENV parameter is set when the shell starts (or, in the  case  of
       login shells, after any profiles are processed), its value is subjected
       to parameter,  command,  arithmetic  and  tilde  substitution  and  the
       resulting  file (if any) is read and executed.  If the ENV parameter is
       not set (and not null) the file $HOME/.kshrc  is  included  (after  the
       above mentioned substitutions have been performed).

       The  exit  status  of the shell is 127 if the command file specified on
       the command line could not be opened, or non-zero  if  a  fatal  syntax
       error  occurred  during  the  execution of a script.  In the absence of
       fatal errors, the exit status is that of the last command executed,  or
       zero, if no command is executed.

   Command Syntax
       The  shell  begins parsing its input by breaking it into words.  Words,
       which are sequences of characters, are  delimited  by  unquoted  white-
       space  characters (space, tab and newline) or meta-characters (<, >, |,
       ;, &, ( and )).  Aside from  delimiting  words,  spaces  and  tabs  are
       ignored,  while newlines usually delimit commands.  The meta-characters
       are used in building the following tokens: <, <&, <<, >, >&,  >>,  etc.
       are  used to specify redirections (see Input/Output Redirection below);
       | is used to create pipelines; |& is used to create  co-processes  (see
       Co-Processes  below); ; is used to separate commands; & is used to cre-
       ate asynchronous pipelines; && and || are used to  specify  conditional
       execution;  ;;  is used in case statements; (( .. )) are used in arith-
       metic expressions; and lastly, ( .. ) are used to create subshells.

       White-space and meta-characters can be quoted individually using  back-
       slash  (\),  or  in groups using double (") or single (') quotes.  Note
       that the following characters are also treated specially by  the  shell
       and  must be quoted if they are to represent themselves: \, ", ', #, $,
       `, ~, {, }, *, ? and [.  The first three of these are  the  above  men-
       tioned quoting characters (see Quoting below); #, if used at the begin-
       ning of a word, introduces a comment -- everything after the  #  up  to
       the  nearest newline is ignored; $ is used to introduce parameter, com-
       mand and arithmetic substitutions (see Substitution  below);  `  intro-
       duces  an  old-style  command  substitution (see Substitution below); ~
       begins a directory expansion (see  Tilde  Expansion  below);  {  and  }
       delimit  csh(1)  style  alternations  (see Brace Expansion below); and,
       finally, *, ? and [ are used in file name  generation  (see  File  Name
       Patterns below).

       As  words  and  tokens  are parsed, the shell builds commands, of which
       there are two basic types: simple-commands, typically programs that are
       executed,  and compound-commands, such as for and if statements, group-
       ing constructs and function definitions.

       A simple-command consists of some combination of parameter  assignments
       (see  Parameters  below),  input/output  redirections (see Input/Output
       Redirections below), and command words; the only  restriction  is  that
       parameter  assignments  come  before  any  command  words.  The command
       words, if any, define the command that is to be executed and its  argu-
       ments.   The  command may be a shell built-in command, a function or an
       external command, i.e., a separate  executable  file  that  is  located
       using  the PATH parameter (see Command Execution below).  Note that all
       command constructs have an exit status: for external commands, this  is
       related  to the status returned by wait(2) (if the command could not be
       found, the exit status is 127, if it could not be  executed,  the  exit
       status  is  126); the exit status of other command constructs (built-in
       commands, functions, compound-commands, pipelines, lists, etc.) are all
       well  defined  and are described where the construct is described.  The
       exit status of a command consisting only of  parameter  assignments  is
       that  of  the  last command substitution performed during the parameter
       assignment or zero if there were no command substitutions.

       Commands can be chained together using the | token to  form  pipelines,
       in which the standard output of each command but the last is piped (see
       pipe(2)) to the standard input of the following command.  The exit sta-
       tus  of a pipeline is that of its last command.  A pipeline may be pre-
       fixed by the ! reserved word which causes the exit status of the  pipe-
       line  to  be  logically  complemented: if the original status was 0 the
       complemented status will be 1, and if the original status  was  not  0,
       then the complemented status will be 0.

       Lists  of commands can be created by separating pipelines by any of the
       following tokens: &&, ||, &, |& and ;.  The first two  are  for  condi-
       tional execution: cmd1 && cmd2 executes cmd2 only if the exit status of
       cmd1 is zero; || is the opposite -- cmd2 is executed only if  the  exit
       status  of  cmd1 is non-zero.  && and || have equal precedence which is
       higher than that of &, |& and ;, which also have equal precedence.  The
       &  token  causes  the  preceding command to be executed asynchronously,
       that is, the shell starts the command, but does not wait for it to com-
       plete (the shell does keep track of the status of asynchronous commands
       -- see Job Control below).  When an  asynchronous  command  is  started
       when  job  control  is disabled (i.e., in most scripts), the command is
       started with signals INT and QUIT ignored  and  with  input  redirected
       from  /dev/null  (however,  redirections  specified in the asynchronous
       command have precedence).  The |& operator starts a co-process which is
       special  kind  of  asynchronous process (see Co-Processes below).  Note
       that a command must follow the && and ||  operators,  while  a  command
       need  not follow &, |& and ;.  The exit status of a list is that of the
       last command executed, with the exception of  asynchronous  lists,  for
       which the exit status is 0.

       Compound  commands  are  created  using the following reserved words --
       these words are only recognized if they are unquoted and  if  they  are
       used  as  the  first word of a command (i.e., they can't be preceded by
       parameter assignments or redirections):

       center;   lfB   lfB   lfB   lfB   lfB   .    case else function  then !
       do   esac if   time [[                       done fi   in   until     {
       elif for  select    while     } Note: Some shells (but  not  this  one)
       execute  control  structure  commands in a subshell when one or more of
       their file descriptors  are  redirected,  so  any  environment  changes
       inside  them  may  fail.   To be portable, the exec statement should be
       used instead to redirect file descriptors before the control structure.

       In  the following compound command descriptions, command lists (denoted
       as list) that are followed by reserved words  must  end  with  a  semi-
       colon, a newline or a (syntactically correct) reserved word.  For exam-
       ple,
              { echo foo; echo bar; }
              { echo foo; echo bar<newline>}
              { { echo foo; echo bar; } }
       are all valid, but
              { echo foo; echo bar }
       is not.

       ( list )
              Execute list in a subshell.  There is no implicit  way  to  pass
              environment changes from a subshell back to its parent.

       { list }
              Compound  construct;  list  is  executed, but not in a subshell.
              Note that { and } are reserved words, not meta-characters.

       case word in [ [(] pattern [| pattern] ... ) list ;; ] ... esac
              The case statement attempts to match word against the  specified
              patterns;  the  list  associated  with  the  first  successfully
              matched pattern is executed.  Patterns used in  case  statements
              are  the  same  as those used for file name patterns except that
              the restrictions regarding . and / are dropped.  Note  that  any
              unquoted space before and after a pattern is stripped; any space
              with a pattern must be quoted.  Both the word and  the  patterns
              are  subject  to parameter, command, and arithmetic substitution
              as well as tilde substitution.  For historical reasons, open and
              close braces may be used instead of in and esac (e.g., case $foo
              { *) echo bar; }).  The exit status of a case statement is  that
              of the executed list; if no list is executed, the exit status is
              zero.

       for name [ in word ... term ] do list done
              where term is either a newline or a ;.  For  each  word  in  the
              specified  word  list, the parameter name is set to the word and
              list is executed.  If in is not used to specify a word list, the
              positional  parameters ("$1", "$2", etc.) are used instead.  For
              historical reasons, open and close braces may be used instead of
              do  and  done (e.g., for i; { echo $i; }).  The exit status of a
              for statement is the last exit status of list; if list is  never
              executed, the exit status is zero.

       if list then list [elif list then list] ... [else list] fi
              If the exit status of the first list is zero, the second list is
              executed; otherwise the list following the elif, if any, is exe-
              cuted with similar consequences.  If all the lists following the
              if and elifs fail (i.e., exit with non-zero  status),  the  list
              following the else is executed.  The exit status of an if state-
              ment is that of non-conditional list that  is  executed;  if  no
              non-conditional list is executed, the exit status is zero.

       select name [ in word ... term ] do list done
              where  term  is  either  a newline or a ;.  The select statement
              provides an automatic method of presenting the user with a  menu
              and  selecting  from  it.   An  enumerated list of the specified
              words is printed on standard error, followed by a  prompt  (PS3,
              normally  `#?  ').  A number corresponding to one of the enumer-
              ated words is then read from standard input, name is set to  the
              selected word (or is unset if the selection is not valid), REPLY
              is set to what was read (leading/trailing  space  is  stripped),
              and  list  is executed.  If a blank line (i.e., zero or more IFS
              characters) is entered, the menu is re-printed without executing
              list.   When  list  completes, the enumerated list is printed if
              REPLY is null, the prompt is printed and so on.  This process is
              continues until an end-of-file is read, an interrupt is received
              or a break statement is executed inside the loop.   If  in  word
              ...  is omitted, the positional parameters are used (i.e., "$1",
              "$2", etc.).  For historical reasons, open and close braces  may
              be  used  instead of do and done (e.g., select i; { echo $i; }).
              The exit status of a select statement is zero if a break  state-
              ment is used to exit the loop, non-zero otherwise.

       until list do list done
              This  works  like  while,  except that the body is executed only
              while the exit status of the first list is non-zero.

       while list do list done
              A while is a prechecked loop.  Its body is executed as often  as
              the exit status of the first list is zero.  The exit status of a
              while statement is the last exit status of the list in the  body
              of  the  loop;  if  the body is not executed, the exit status is
              zero.

       function name { list }
              Defines the function name.   See  Functions  below.   Note  that
              redirections specified after a function definition are performed
              whenever the function is executed, not when the function defini-
              tion is executed.

       name () command
              Mostly the same as function.  See Functions below.

       time [ -p ] [ pipeline ]
              The  time  reserved  word  is described in the Command Execution
              section.

       (( expression ))
              The arithmetic expression expression is evaluated; equivalent to
              let  "expression".   See Arithmetic Expressions and the let com-
              mand below.

       [[ expression ]]
              Similar to the test and [ ... ] commands (described later), with
              the following exceptions:
                ·    Field  splitting  and  file  name generation are not per-
                     formed on arguments.
                ·    The -a (and) and -o (or) operators are replaced  with  &&
                     and ||, respectively.
                ·    Operators (e.g., -f, =, !, etc.) must be unquoted.
                ·    The  second  operand of != and = expressions are patterns
                     (e.g., the comparison in
                                        [[ foobar = f*r ]]
                     succeeds).
                ·    There are two additional binary operators: < and >  which
                     return  true  if their first string operand is less than,
                     or greater than, their  second  string  operand,  respec-
                     tively.
                ·    The  single  argument  form  of  test, which tests if the
                     argument has non-zero length, is  not  valid  -  explicit
                     operators must always be used, e.g., instead of
                                              [ str ]
                     use
                                           [[ -n str ]]
                ·    Parameter,  command and arithmetic substitutions are per-
                     formed as expressions are evaluated and  lazy  expression
                     evaluation  is  used  for  the && and || operators.  This
                     means that in the statement
                                  [[ -r foo && $(< foo) = b*r ]]
                     the $(< foo) is evaluated if and only  if  the  file  foo
                     exists and is readable.

   Quoting
       Quoting  is used to prevent the shell from treating characters or words
       specially.  There are three methods of quoting:  First,  \  quotes  the
       following  character,  unless it is at the end of a line, in which case
       both the \ and the newline are stripped.  Second, a  single  quote  (')
       quotes  everything  up  to the next single quote (this may span lines).
       Third, a double quote (") quotes all characters, except $, ` and \,  up
       to  the  next unquoted double quote.  $ and ` inside double quotes have
       their usual meaning (i.e., parameter, command or  arithmetic  substitu-
       tion)  except  no field splitting is carried out on the results of dou-
       ble-quoted substitutions.  If a \ inside a double-quoted string is fol-
       lowed by \, $, ` or ", it is replaced by the second character; if it is
       followed by a newline, both the \ and the newline are stripped;  other-
       wise, both the \ and the character following are unchanged.

       Note:  An  earlier  version  of  ksh(1)  changed  the interpretation of
       sequences of the form "...`...\"...`.."  according to  whether  or  not
       POSIX mode was in effect.  In the current implementation, the backslash
       in \" is seen and removed by the outer "...", so the backslash  is  not
       seen by the inner `...`.

   Aliases
       There  are  two  types  of  aliases: normal command aliases and tracked
       aliases.  Command aliases are normally used as a short hand for a  long
       or  often  used command.  The shell expands command aliases (i.e., sub-
       stitutes the alias name for its value) when it reads the first word  of
       a  command.   An  expanded  alias  is  re-processed  to  check for more
       aliases.  If a command alias ends in a space or tab, the following word
       is also checked for alias expansion.  The alias expansion process stops
       when a word that is not an alias is found, when a quoted word is  found
       or when an alias word that is currently being expanded is found.

       The following command aliases are defined automatically by the shell:
              autoload='typeset -fu'
              functions='typeset -f'
              hash='alias -t'
              history='fc -l'
              integer='typeset -i'
              local='typeset'
              login='exec login'
              nohup='nohup '
              r='fc -e -'
              stop='kill -STOP'
              suspend='kill -STOP $$'
              type='whence -v'

       Tracked aliases allow the shell to remember where it found a particular
       command.  The first time the shell does a path  search  for  a  command
       that  is  marked as a tracked alias, it saves the full path of the com-
       mand.  The next time the command is  executed,  the  shell  checks  the
       saved  path  to see that it is still valid, and if so, avoids repeating
       the path search.  Tracked aliases can be listed and created using alias
       -t.   Note  that changing the PATH parameter clears the saved paths for
       all tracked aliases.  If the trackall  option  is  set  (i.e.,  set  -o
       trackall or set -h), the shell tracks all commands.  This option is set
       automatically for non-interactive shells.  For interactive shells, only
       the  following  commands are automatically tracked: cat, cc, chmod, cp,
       date, ed, emacs, grep, ls, mail, make, mv, pr, rm, sed, sh, vi and who.

   Substitution
       The first step the shell takes in executing a simple-command is to per-
       form substitutions on the words of the command.  There are three  kinds
       of  substitution: parameter, command and arithmetic.  Parameter substi-
       tutions, which are described in detail in the next  section,  take  the
       form $name or ${...}; command substitutions take the form $(command) or
       `command`; and arithmetic substitutions take the form  $((expression)).

       If  a substitution appears outside of double quotes, the results of the
       substitution are generally subject to word or field splitting according
       to the current value of the IFS parameter.  The IFS parameter specifies
       a list of characters which are used to break a string up  into  several
       words;  any  characters from the set space, tab and newline that appear
       in the IFS characters are called IFS white space.  Sequences of one  or
       more  IFS  white space characters, in combination with zero or one non-
       IFS white space characters delimit a field.  As a special case, leading
       and  trailing IFS white space is stripped (i.e., no leading or trailing
       empty field is created by it); leading or trailing non-IFS white  space
       does  create an empty field.  Example: if IFS is set to `<space>:', the
       sequence of  characters  `<space>A<space>:<space><space>B::D'  contains
       four  fields:  `A', `B', `' and `D'.  Note that if the IFS parameter is
       set to the null string, no field splitting is done; if the parameter is
       unset, the default value of space, tab and newline is used.

       The  results of substitution are, unless otherwise specified, also sub-
       ject to brace expansion and file name expansion (see the relevant  sec-
       tions below).

       A command substitution is replaced by the output generated by the spec-
       ified command, which is run in a subshell.   For  $(command)  substitu-
       tions,  normal  quoting rules are used when command is parsed, however,
       for the `command` form, a \ followed by any of $, ` or \ is stripped (a
       \  followed by any other character is unchanged).  As a special case in
       command substitutions, a command of the form < file is  interpreted  to
       mean  substitute  the contents of file ($(< foo) has the same effect as
       $(cat foo), but it is carried out more efficiently because  no  process
       is started).
       NOTE: $(command) expressions are currently parsed by finding the match-
       ing parenthesis, regardless of quoting.  This will hopefully  be  fixed
       soon.

       Arithmetic  substitutions  are  replaced  by the value of the specified
       expression.  For example, the command echo $((2+3*4)) prints  14.   See
       Arithmetic Expressions for a description of an expression.

   Parameters
       Parameters  are  shell variables; they can be assigned values and their
       values can be accessed using a  parameter  substitution.   A  parameter
       name is either one of the special single punctuation or digit character
       parameters described below, or a letter followed by zero or  more  let-
       ters or digits (`_' counts as a letter).  The later form can be treated
       as arrays by appending an array index of the form: [expr] where expr is
       an  arithmetic  expression.  Array indices are currently limited to the
       range 0 through 1023, inclusive.  Parameter substitutions take the form
       $name,  ${name}  or  ${name[expr]}, where name is a parameter name.  If
       substitution is performed on a parameter (or an  array  parameter  ele-
       ment)  that is not set, a null string is substituted unless the nounset
       option (set -o nounset or set -u)  is  set,  in  which  case  an  error
       occurs.

       Parameters  can  be  assigned  values  in a number of ways.  First, the
       shell implicitly sets some parameters like #, PWD, etc.;  this  is  the
       only  way  the  special  single  character parameters are set.  Second,
       parameters are  imported  from  the  shell's  environment  at  startup.
       Third, parameters can be assigned values on the command line, for exam-
       ple, `FOO=bar' sets  the  parameter  FOO  to  bar;  multiple  parameter
       assignments  can be given on a single command line and they can be fol-
       lowed by a simple-command, in which case the assignments are in  effect
       only  for  the  duration  of  the  command  (such  assignments are also
       exported, see below for implications of  this).   Note  that  both  the
       parameter  name and the = must be unquoted for the shell to recognize a
       parameter assignment.  The fourth way of setting a  parameter  is  with
       the  export,  readonly  and typeset commands; see their descriptions in
       the Command Execution section.  Fifth, for and select loops set parame-
       ters as well as the getopts, read and set -A commands.  Lastly, parame-
       ters can be assigned values using assignment  operators  inside  arith-
       metic  expressions  (see  Arithmetic  Expressions  below)  or using the
       ${name=value} form of parameter substitution (see below).

       Parameters with the export attribute (set using the export  or  typeset
       -x  commands,  or by parameter assignments followed by simple commands)
       are put in the environment (see environ(7))  of  commands  run  by  the
       shell as name=value pairs.  The order in which parameters appear in the
       environment of a command is unspecified.  When the shell starts up,  it
       extracts parameters and their values from its environment and automati-
       cally sets the export attribute for those parameters.

       Modifiers can be applied to the ${name} form of parameter substitution:

       ${name:-word}
              if  name  is set and not null, it is substituted, otherwise word
              is substituted.

       ${name:+word}
              if name is set and not  null,  word  is  substituted,  otherwise
              nothing is substituted.

       ${name:=word}
              if  name is set and not null, it is substituted, otherwise it is
              assigned word and the resulting value of name is substituted.

       ${name:?word}
              if name is set and not null, it is substituted,  otherwise  word
              is  printed  on  standard error (preceded by name:) and an error
              occurs (normally causing termination of a shell script, function
              or  .-script).  If word is omitted the string `parameter null or
              not set' is used instead.

       In the above modifiers, the : can be omitted, in which case the  condi-
       tions  only  depend on name being set (as opposed to set and not null).
       If word is needed, parameter, command, arithmetic and  tilde  substitu-
       tion are performed on it; if word is not needed, it is not evaluated.

       The following forms of parameter substitution can also be used:

       ${#name}
              The  number  of  positional parameters if name is *, @ or is not
              specified, or the length of the string value of parameter  name.

       ${#name[*]}, ${#name[@]}
              The number of elements in the array name.

       ${name#pattern}, ${name##pattern}
              If pattern matches the beginning of the value of parameter name,
              the matched text is deleted from the result of substitution.   A
              single  #  results in the shortest match, two #'s results in the
              longest match.

       ${name%pattern}, ${name%%pattern}
              Like ${..#..} substitution, but it deletes from the end  of  the
              value.

       The  following  special  parameters are implicitly set by the shell and
       cannot be set directly using assignments:

       !      Process id of the last background process started.  If no  back-
              ground processes have been started, the parameter is not set.

       #      The number of positional parameters (i.e., $1, $2, etc.).

       $      The process ID of the shell, or the PID of the original shell if
              it is a subshell.

       -      The concatenation of the current single letter options (see  set
              command below for list of options).

       ?      The  exit  status of the last non-asynchronous command executed.
              If the last command was killed by a signal, $?  is  set  to  128
              plus the signal number.

       0      The name the shell was invoked with (i.e., argv[0]), or the com-
              mand-name if it was invoked with the -c option and the  command-
              name was supplied, or the file argument, if it was supplied.  If
              the posix option is not set, $0 is the name of the current func-
              tion or script.

       1 ... 9
              The  first  nine positional parameters that were supplied to the
              shell, function or .-script.  Further positional parameters  may
              be accessed using ${number}.

       *      All  positional  parameters  (except  parameter  0), i.e., $1 $2
              $3....  If used outside of double quotes, parameters  are  sepa-
              rate  words  (which  are  subjected  to word splitting); if used
              within double quotes, parameters  are  separated  by  the  first
              character  of  the  IFS parameter (or the empty string if IFS is
              null).

       @      Same as $*, unless it is used inside  double  quotes,  in  which
              case  a separate word is generated for each positional parameter
              - if there are no positional parameters, no  word  is  generated
              ("$@"  can be used to access arguments, verbatim, without losing
              null arguments or splitting arguments with spaces).

       The following parameters are set and/or used by the shell:

       _ (underscore)
              When an external command is executed by the shell, this  parame-
              ter  is set in the environment of the new process to the path of
              the executed command.  In interactive  use,  this  parameter  is
              also  set  in  the parent shell to the last word of the previous
              command.  When MAILPATH messages are evaluated,  this  parameter
              contains the name of the file that changed (see MAILPATH parame-
              ter below).

       CDPATH Search path for the cd built-in command.  Works the same way  as
              PATH  for those directories not beginning with / in cd commands.
              Note that if CDPATH is set and does not contain . nor  an  empty
              path, the current directory is not searched.

       COLUMNS
              Set  to  the  number of columns on the terminal or window.  Cur-
              rently set to the cols value as  reported  by  stty(1)  if  that
              value  is  non-zero.   This parameter is used by the interactive
              line editing modes, and by select, set -o and kill  -l  commands
              to format information in columns.

       EDITOR If  the VISUAL parameter is not set, this parameter controls the
              command line editing mode for interactive  shells.   See  VISUAL
              parameter below for how this works.

       ENV    If this parameter is found to be set after any profile files are
              executed, the expanded value is used as a shell  start-up  file.
              It typically contains function and alias definitions.

       ERRNO  Integer  value  of  the  shell's errno variable -- indicates the
              reason the last system call failed.

              Not implemented yet.

       EXECSHELL
              If set, this parameter is assumed to contain the shell  that  is
              to  be  used to execute commands that execve(2) fails to execute
              and which do not start with a `#! shell' sequence.

       FCEDIT The editor used by the fc command (see below).

       FPATH  Like PATH, but used when an undefined function  is  executed  to
              locate the file defining the function.  It is also searched when
              a command can't be found using PATH.  See  Functions  below  for
              more information.

       HISTFILE
              The  name  of the file used to store history.  When assigned to,
              history is loaded from the specified file.  Also, several  invo-
              cations of the shell running on the same machine will share his-
              tory if their HISTFILE parameters all point at the same file.
              NOTE: if HISTFILE isn't set, no history file is used.   This  is
              different   from   the   original   Korn   shell,   which   uses
              $HOME/.sh_history; in future, pdksh may also use a default  his-
              tory file.

       HISTSIZE
              The number of commands normally stored for history, default 128.

       HOME   The default directory for the cd command and the  value  substi-
              tuted for an unqualified ~ (see Tilde Expansion below).

       IFS    Internal  field  separator,  used during substitution and by the
              read command, to split values into distinct arguments;  normally
              set  to  space,  tab  and  newline.   See Substitution above for
              details.
              Note: this parameter is not imported from the  environment  when
              the shell is started.

       KSH_VERSION
              The version of shell and the date the version was created (read-
              only).  See also the version commands in Emacs Editing Mode  and
              Vi Editing Mode sections, below.

       LINENO The  line  number  of  the function or shell script that is cur-
              rently being executed.

       LINES  Set to the number of lines on the terminal or window.

              Not implemented yet.

       MAIL   If set, the user will be informed of the arrival of mail in  the
              named file.  This parameter is ignored if the MAILPATH parameter
              is set.

       MAILCHECK
              How often, in seconds, the shell will  check  for  mail  in  the
              file(s)  specified  by MAIL or MAILPATH.  If 0, the shell checks
              before each prompt.  The default is 600 (10 minutes).

       MAILPATH
              A list of files to be checked for mail.  The list is colon sepa-
              rated,  and each file may be followed by a ? and a message to be
              printed if new mail has arrived.  Command, parameter and  arith-
              metic substitution is performed on the message, and, during sub-
              stitution, the parameter $_ contains the name of the file.   The
              default message is you have mail in $_.

       OLDPWD The  previous  working  directory.  Unset if cd has not success-
              fully changed directories since the shell  started,  or  if  the
              shell doesn't know where it is.

       OPTARG When  using  getopts,  it  contains  the  argument  for a parsed
              option, if it requires one.

       OPTIND The index of the last argument  processed  when  using  getopts.
              Assigning  1  to  this parameter causes getopts to process argu-
              ments from the beginning the next time it is invoked.

       PATH   A colon separated list of directories  that  are  searched  when
              looking  for  commands and .'d files.  An empty string resulting
              from a leading or trailing colon,  or  two  adjacent  colons  is
              treated as a `.', the current directory.

       POSIXLY_CORRECT
              If  set,  this  parameter causes the posix option to be enabled.
              See POSIX Mode below.

       PPID   The process ID of the shell's parent (readonly).

       PS1    PS1 is the primary prompt for  interactive  shells.   Parameter,
              command  and  arithmetic  substitutions  are performed, and ! is
              replaced with the current command number (see fc command below).
              A literal ! can be put in the prompt by placing !! in PS1.  Note
              that since the command line editors try to figure out  how  long
              the  prompt  is  (so  they  know  how  far  it is to edge of the
              screen), escape codes in the prompt tend to mess things up.  You
              can  tell  the  shell  not  to  count certain sequences (such as
              escape codes) by prefixing your prompt with a non-printing char-
              acter (such as control-A) followed by a carriage return and then
              delimiting the escape codes with  this  non-printing  character.
              If  you  don't  have  any non-printing characters, you're out of
              luck...  BTW, don't blame me for this hack; it's in the original
              ksh.  Default is `$ ' for non-root users, `# ' for root.

       PS2    Secondary  prompt  string, by default `> ', used when more input
              is needed to complete a command.

       PS3    Prompt used by select statement when reading a  menu  selection.
              Default is `#? '.

       PS4    Used  to prefix commands that are printed during execution trac-
              ing (see set -x command below).  Parameter, command  and  arith-
              metic substitutions are performed before it is printed.  Default
              is `+ '.

       PWD    The current working directory.  Maybe unset  or  null  if  shell
              doesn't know where it is.

       RANDOM A  simple  random number generator.  Every time RANDOM is refer-
              enced, it is assigned the next number in a random number series.
              The point in the series can be set by assigning a number to RAN-
              DOM (see rand(3)).

       REPLY  Default parameter for the read command if no  names  are  given.
              Also  used  in select loops to store the value that is read from
              standard input.

       SECONDS
              The number of seconds since the shell started or, if the parame-
              ter  has  been  assigned an integer value, the number of seconds
              since the assignment plus the value that was assigned.

       TMOUT  If set to a positive integer in an interactive shell, it  speci-
              fies the maximum number of seconds the shell will wait for input
              after printing  the  primary  prompt  (PS1).   If  the  time  is
              exceeded, the shell exits.

       TMPDIR The  directory  shell  temporary  files are created in.  If this
              parameter is not set, or does not contain the absolute path of a
              writable directory, temporary files are created in /tmp.

       VISUAL If  set,  this  parameter controls the command line editing mode
              for interactive shells.  If the last component of the path spec-
              ified  in this parameter contains the string vi, emacs or gmacs,
              the vi, emacs or gmacs (Gosling emacs) editing mode is  enabled,
              respectively.

   Tilde Expansion
       Tilde expansion, which is done in parallel with parameter substitution,
       is done on words starting with an unquoted ~.  The characters following
       the  tilde,  up to the first /, if any, are assumed to be a login name.
       If the login name is empty, + or -, the value of the HOME, PWD, or OLD-
       PWD  parameter  is  substituted, respectively.  Otherwise, the password
       file is searched for the login name, and the tilde expression  is  sub-
       stituted  with  the  user's  home  directory.  If the login name is not
       found in the password file or if any quoting or parameter  substitution
       occurs in the login name, no substitution is performed.

       In  parameter  assignments  (those  preceding a simple-command or those
       occurring in the arguments of alias, export,  readonly,  and  typeset),
       tilde  expansion  is done after any unquoted colon (:), and login names
       are also delimited by colons.

       The home directory of previously expanded login names  are  cached  and
       re-used.   The  alias -d command may be used to list, change and add to
       this cache (e.g., `alias -d fac=/usr/local/facilities; cd ~fac/bin').

   Brace Expansion (alternation)
       Brace expressions, which take the form
              prefix{str1,...,strN}suffix
       are expanded to N words, each of which is the concatenation of  prefix,
       stri  and  suffix  (e.g.,  `a{c,b{X,Y},d}e'  expands to four word: ace,
       abXe, abYe, and ade).  As noted in the example, brace  expressions  can
       be  nested  and  the resulting words are not sorted.  Brace expressions
       must contain an unquoted comma (,) for expansion to occur (i.e., {} and
       {foo}  are not expanded).  Brace expansion is carried out after parame-
       ter substitution and before file name generation.

   File Name Patterns
       A file name pattern is a word containing one or more unquoted  ?  or  *
       characters or [..] sequences.  Once brace expansion has been performed,
       the shell replaces file name patterns with the sorted names of all  the
       files  that  match  the  pattern  (if  no files match, the word is left
       unchanged).  The pattern elements have the following meaning:

       ?      matches any single character.

       *      matches any sequence of characters.

       [..]   matches any of the characters inside the  brackets.   Ranges  of
              characters can be specified by separating two characters by a -,
              e.g., [a0-9] matches the letter a or any  digit.   In  order  to
              represent itself, a - must either be quoted or the first or last
              character in the character list.  Similarly, a ] must be  quoted
              or  the  first  character  in the list if it is represent itself
              instead of the end of the list.  Also, a  !   appearing  at  the
              start  of the list has special meaning (see below), so to repre-
              sent itself it must be quoted or appear later in the list.

       [!..]  like [..], except it matches any character not inside the brack-
              ets.

       *(pattern| ... |pattern)
              matches  any  string  of  characters  that  matches zero or more
              occurrences of the specified  patterns.   Example:  the  pattern
              *(foo|bar)  matches  the  strings `', `foo', `bar', `foobarfoo',
              etc..

       +(pattern| ... |pattern)
              matches any string of characters that matches one or more occur-
              rences   of   the  specified  patterns.   Example:  the  pattern
              +(foo|bar) matches the strings `foo', `bar', `foobarfoo',  etc..

       ?(pattern| ... |pattern)
              matches  the  empty  string  or a string that matches one of the
              specified  patterns.   Example:  the  pattern  ?(foo|bar)   only
              matches the strings `', `foo' and `bar'.

       @(pattern| ... |pattern)
              matches  a  string  that  matches one of the specified patterns.
              Example: the pattern @(foo|bar) only matches the  strings  `foo'
              and `bar'.

       !(pattern| ... |pattern)
              matches any string that does not match one of the specified pat-
              terns.  Examples: the pattern  !(foo|bar)  matches  all  strings
              except `foo' and `bar'; the pattern !(*) matches no strings; the
              pattern !(?)* matches all strings (think about it).

       Note that pdksh currently never matches . and .., but the original ksh,
       Bourne sh and bash do, so this may have to change (too bad).

       Note  that none of the above pattern elements match either a period (.)
       at the start of a file name or a slash (/), even if they are explicitly
       used  in  a [..] sequence; also, the names . and ..  are never matched,
       even by the pattern .*.

       If the markdirs option is set, any directories that  result  from  file
       name generation are marked with a trailing /.

       The POSIX character classes (i.e., [:class-name:] inside a [..] expres-
       sion) are not yet implemented.

   Input/Output Redirection
       When a command is executed, its standard  input,  standard  output  and
       standard error (file descriptors 0, 1 and 2, respectively) are normally
       inherited from the shell.  Three exceptions to  this  are  commands  in
       pipelines,  for  which  standard input and/or standard output are those
       set up by the pipeline, asynchronous commands created when job  control
       is  disabled,  for  which  standard  input  is initially set to be from
       /dev/null, and commands for which any  of  the  following  redirections
       have been specified:

       > file standard  output is redirected to file.  If file does not exist,
              it is created; if it does exist,  is  a  regular  file  and  the
              noclobber  option is set, an error occurs, otherwise the file is
              truncated.  Note that this means the command cmd  <  foo  >  foo
              will  open foo for reading and then truncate it when it opens it
              for writing, before cmd gets a chance to actually read foo.

       >| file
              same as >, except the file is truncated, even if  the  noclobber
              option is set.

       >> file
              same  as  >,  except  the  file  an existing file is appended to
              instead of being truncated.  Also, the file is opened in  append
              mode,  so writes always go to the end of the file (see open(2)).

       < file standard input is redirected from  file,  which  is  opened  for
              reading.

       <> file
              same as <, except the file is opened for reading and writing.

       << marker
              after reading the command line containing this kind of redirect-
              ion (called a here document), the shell copies  lines  from  the
              command  source  into  a  temporary  file  until a line matching
              marker is read.  When the command is executed, standard input is
              redirected  from  the  temporary  file.   If  marker contains no
              quoted characters, the contents of the temporary file  are  pro-
              cessed  as if enclosed in double quotes each time the command is
              executed, so parameter, command and arithmetic substitutions are
              performed,  along  with  backslash  (\)  escapes for $, `, \ and
              \newline.  If multiple here documents are used on the same  com-
              mand line, they are saved in order.

       <<- marker
              same  as  <<, except leading tabs are stripped from lines in the
              here document.

       <& fd  standard input is duplicated from file descriptor fd.  fd can be
              a  single  digit,  indicating  the  number  of  an existing file
              descriptor, the letter p, indicating the file descriptor associ-
              ated with the output of the current co-process, or the character
              -, indicating standard input is to be closed.

       >& fd  same as <&, except the operation is done on standard output.

       In any of the above redirections, the file  descriptor  that  is  redi-
       rected  (i.e.,  standard  input  or  standard output) can be explicitly
       given by preceding the redirection with  a  single  digit.   Parameter,
       command  and  arithmetic substitutions, tilde substitutions and (if the
       shell is interactive) file name generation are  all  performed  on  the
       file,  marker and fd arguments of redirections.  Note however, that the
       results of any file name generation are only used if a single  file  is
       matched;  if  multiple  files  match, the word with the unexpanded file
       name generation characters is used.  Note that  in  restricted  shells,
       redirections which can create files cannot be used.

       For  simple-commands,  redirections may appear anywhere in the command,
       for compound-commands (if  statements,  etc.),  any  redirections  must
       appear at the end.  Redirections are processed after pipelines are cre-
       ated and in the order they are given, so
              cat /foo/bar 2>&1 > /dev/null | cat -n
       will print an error with a line number prepended to it.

   Arithmetic Expressions
       Integer arithmetic expressions can be used with the let command, inside
       $((..))  expressions,  inside  array  references (e.g., name[expr]), as
       numeric arguments to the test command, and as the value of  an  assign-
       ment to an integer parameter.

       Expression  may contain alpha-numeric parameter identifiers, array ref-
       erences, and integer constants and may be combined with the following C
       operators (listed and grouped in increasing order of precedence).

       Unary operators:
              + - ! ~ ++ --

       Binary operators:
              ,
              = *= /= %= += -= <<= >>= &= ^= |=
              ||
              &&
              |
              ^
              &
              == !=
              < <= >= >
              << >>
              + -
              * / %

       Ternary operator:
              ?: (precedence is immediately higher than assignment)

       Grouping operators:
              ( )

       Integer constants may be specified with arbitrary bases using the nota-
       tion base#number, where base is a decimal integer specifying the  base,
       and number is a number in the specified base.

       The operators are evaluated as follows:

              unary +
                     result is the argument (included for completeness).

              unary -
                     negation.

              !      logical  not;  the  result is 1 if argument is zero, 0 if
                     not.

              ~      arithmetic (bit-wise) not.

              ++     increment; must be applied to a parameter (not a  literal
                     or other expression) - the parameter is incremented by 1.
                     When used as a prefix operator, the result is the  incre-
                     mented  value  of  the  parameter, when used as a postfix
                     operator, the result is the original value of the parame-
                     ter.

              --     similar  to ++, except the parameter is decremented by 1.

              ,      separates two arithmetic expressions; the left hand  side
                     is  evaluated first, then the right.  The result is value
                     of the expression on the right hand side.

              =      assignment; variable on the left is set to the  value  on
                     the right.

              *= /= %= += -= <<= >>= &= ^= |=
                     assignment  operators;  <var> <op>= <expr> is the same as
                     <var> = <var> <op> ( <expr> ).

              ||     logical or; the result is 1 if either  argument  is  non-
                     zero,  0 if not.  The right argument is evaluated only if
                     the left argument is zero.

              &&     logical and; the result is 1 if both arguments  are  non-
                     zero,  0 if not.  The right argument is evaluated only if
                     the left argument is non-zero.

              |      arithmetic (bit-wise) or.

              ^      arithmetic (bit-wise) exclusive-or.

              &      arithmetic (bit-wise) and.

              ==     equal; the result is 1 if both arguments are equal, 0  if
                     not.

              !=     not equal; the result is 0 if both arguments are equal, 1
                     if not.

              <      less than; the result is 1 if the left argument  is  less
                     than the right, 0 if not.

              <= >= >
                     less  than or equal, greater than or equal, greater than.
                     See <.

              << >>  shift left (right); the result is the left argument  with
                     its  bits shifted left (right) by the amount given in the
                     right argument.

              + - * /
                     addition, subtraction, multiplication, and division.

              %      remainder; the result is the remainder of the division of
                     the  left  argument by the right.  The sign of the result
                     is unspecified if either argument is negative.

              <arg1> ? <arg2> : <arg3>
                     if <arg1> is non-zero, the result  is  <arg2>,  otherwise
                     <arg3>.

   Co-Processes
       A  co-process,  which is a pipeline created with the |& operator, is an
       asynchronous process that the shell can both write to (using print  -p)
       and  read from (using read -p).  The input and output of the co-process
       can also be manipulated using >&p and <&p  redirections,  respectively.
       Once  a co-process has been started, another can't be started until the
       co-process exits, or until the co-process  input  has  been  redirected
       using  an exec n>&p redirection.  If a co-process's input is redirected
       in this way, the next co-process to be started will  share  the  output
       with  the first co-process, unless the output of the initial co-process
       has been redirected using an exec n<&p redirection.

       Some notes concerning co-processes:
         ·    the only way to close the co-process input  (so  the  co-process
              reads  an  end-of-file)  is  to redirect the input to a numbered
              file descriptor and then close that file descriptor (e.g.,  exec
              3>&p;exec 3>&-).
         ·    in  order  for  co-processes to share a common output, the shell
              must keep the write portion of the output pipe open.  This means
              that  end  of  file  will not be detected until all co-processes
              sharing the co-process output have exited (when they  all  exit,
              the  shell closes its copy of the pipe).  This can be avoided by
              redirecting the output to a numbered file  descriptor  (as  this
              also causes the shell to close its copy).  Note that this behav-
              iour is slightly different from the original  Korn  shell  which
              closes its copy of the write portion of the co-processes' output
              when the most recently started co-process (instead of  when  all
              sharing co-processes) exits.
         ·    print -p will ignore SIGPIPE signals during writes if the signal
              is not being trapped or ignored; the same is not true if the co-
              process input has been duplicated to another file descriptor and
              print -un is used.

   Functions
       Functions are defined using either Korn shell function name  syntax  or
       the  Bourne/POSIX  shell  name()  syntax  (see below for the difference
       between the two forms).  Functions are like .-scripts in that they  are
       executed  in  the current environment, however, unlike .-scripts, shell
       arguments (i.e., positional parameters, $1,  etc.)  are  never  visible
       inside  them.  When the shell is determining the location of a command,
       functions are searched after special built-in commands, and before reg-
       ular and non-regular built-ins, and before the PATH is searched.

       An  existing  function  may be deleted using unset -f function-name.  A
       list of functions can be obtained using typeset  +f  and  the  function
       definitions  can  be  listed  using  typeset -f.  autoload (which is an
       alias for typeset -fu) may be used to create undefined functions;  when
       an  undefined  function is executed, the shell searches the path speci-
       fied in the FPATH parameter for a file with the same name as the  func-
       tion,  which,  if  found  is read and executed.  If after executing the
       file, the named function is found to be defined, the function  is  exe-
       cuted,  otherwise,  the  normal  command search is continued (i.e., the
       shell searches the regular built-in command table and PATH).  Note that
       if  a command is not found using PATH, an attempt is made to autoload a
       function using FPATH (this is an undocumented feature of  the  original
       Korn shell).

       Functions  can  have two attributes, trace and export, which can be set
       with typeset -ft and typeset -fx, respectively.  When a traced function
       is  executed,  the shell's xtrace option is turned on for the functions
       duration, otherwise the  xtrace  option  is  turned  off.   The  export
       attribute  of  functions  is  currently not used.  In the original Korn
       shell, exported functions are visible to shell scripts  that  are  exe-
       cuted.

       Since  functions are executed in the current shell environment, parame-
       ter assignments made inside functions are visible  after  the  function
       completes.   If this is not the desired effect, the typeset command can
       be used inside a function to create a local parameter.  Note that  spe-
       cial parameters (e.g., $$, $!) can't be scoped in this way.

       The  exit  status of a function is that of the last command executed in
       the function.  A function can be made to finish immediately  using  the
       return  command;  this  may also be used to explicitly specify the exit
       status.

       Functions defined with the function reserved word are  treated  differ-
       ently  in  the  following ways from functions defined with the () nota-
       tion:
         ·    the $0 parameter is set to the name  of  the  function  (Bourne-
              style functions leave $0 untouched).
         ·    parameter  assignments  preceding function calls are not kept in
              the shell environment  (executing  Bourne-style  functions  will
              keep assignments).
         ·    OPTIND  is  saved/reset  and restored on entry and exit from the
              function so getopts can be used properly both inside and outside
              the  function (Bourne-style functions leave OPTIND untouched, so
              using getopts inside a function interferes  with  using  getopts
              outside the function).  In the future, the following differences
              will also be added:
         ·    A separate trap/signal environment will be used during the  exe-
              cution  of  functions.   This  will mean that traps set inside a
              function will not affect the shell's traps and signals that  are
              not  ignored  in  the shell (but may be trapped) will have their
              default effect in a function.
         ·    The EXIT trap, if set in a function, will be executed after  the
              function returns.

   POSIX Mode
       The  shell  is  intended to be POSIX compliant, however, in some cases,
       POSIX behaviour is contrary either to the original Korn shell behaviour
       or to user convenience.  How the shell behaves in these cases is deter-
       mined by the state of the posix option (set -o posix) -- if it  is  on,
       the POSIX behaviour is followed, otherwise it is not.  The posix option
       is set automatically when the shell starts up if the  environment  con-
       tains  the  POSIXLY_CORRECT parameter.  (The shell can also be compiled
       so that it is in POSIX mode by default, however  this  is  usually  not
       desirable).

       The following is a list of things that are affected by the state of the
       posix option:
         ·    kill -l output: in posix mode, signal names  are  listed  one  a
              single  line;  in  non-posix  mode,  signal  numbers,  names and
              descriptions are printed in columns.  In future,  a  new  option
              (-v perhaps) will be added to distinguish the two behaviours.
         ·    fg exit status: in posix mode, the exit status is 0 if no errors
              occur; in non-posix mode, the exit status is that  of  the  last
              foregrounded job.
         ·    eval  exit  status:  if eval gets to see an empty command (e.g.,
              eval "`false`"), its exit status in posix mode will  be  0.   In
              non-posix  mode,  it will be the exit status of the last command
              substitution that was done in the processing of the arguments to
              eval (or 0 if there were no command substitutions).
         ·    getopts:  in  posix  mode,  options must start with a -; in non-
              posix mode, options can start with either - or +.
         ·    brace expansion (also known  as  alternation):  in  posix  mode,
              brace  expansion is disabled; in non-posix mode, brace expansion
              enabled.  Note that set -o posix (or setting the POSIXLY_CORRECT
              parameter)  automatically turns the braceexpand option off, how-
              ever it can be explicitly turned on later.
         ·    set -: in posix mode, this does not clear the verbose or  xtrace
              options; in non-posix mode, it does.
         ·    set  exit  status: in posix mode, the exit status of set is 0 if
              there are no errors; in non-posix mode, the exit status is  that
              of  any  command  substitutions  performed in generating the set
              command.  For example, `set -- `false`; echo  $?'  prints  0  in
              posix mode, 1 in non-posix mode.  This construct is used in most
              shell scripts that use the old getopt(1) command.
         ·    argument expansion of alias, export, readonly, and typeset  com-
              mands:  in  posix  mode, normal argument expansion done; in non-
              posix mode, field splitting, file globing, brace  expansion  and
              (normal)  tilde  expansion  are turned off, and assignment tilde
              expansion is turned on.
         ·    signal specification: in posix mode, signals can be specified as
              digits  only  if signal numbers match POSIX values (i.e., HUP=1,
              INT=2, QUIT=3, ABRT=6, KILL=9, ALRM=14, and  TERM=15);  in  non-
              posix mode, signals can be always digits.
         ·    alias  expansion: in posix mode, alias expansion is only carried
              out when reading command words; in non-posix mode, alias  expan-
              sion is carried out on any word following an alias that ended in
              a space.  For example, the following for loop
              alias a='for ' i='j'
              a i in 1 2; do echo i=$i j=$j; done
       uses parameter i in posix mode, j in non-posix mode.
         ·    test: in posix mode, the expression "-t" (preceded by some  num-
              ber  of "!" arguments) is always true as it is a non-zero length
              string; in non-posix mode, it tests if file descriptor  1  is  a
              tty  (i.e.,  the  fd argument to the -t test may be left out and
              defaults to 1).

   Command Execution
       After evaluation of command line arguments, redirections and  parameter
       assignments,  the  type of command is determined: a special built-in, a
       function, a regular built-in or the name of a  file  to  execute  found
       using  the  PATH  parameter.   The  checks are made in the above order.
       Special built-in commands differ from other commands in that  the  PATH
       parameter is not used to find them, an error during their execution can
       cause a non-interactive shell to exit and  parameter  assignments  that
       are  specified before the command are kept after the command completes.
       Just to confuse things, if the posix option is turned off (see set com-
       mand  below)  some  special  commands are very special in that no field
       splitting, file globing, brace expansion nor tilde  expansion  is  per-
       formed  on arguments that look like assignments.  Regular built-in com-
       mands are different only in that the PATH parameter is not used to find
       them.

       The  original  ksh and POSIX differ somewhat in which commands are con-
       sidered special or regular:

       POSIX special commands

              lw(8m)fB  lw(8m)fB  lw(8m)fB  lw(8m)fB  lw(8m)fB  .    .    con-
              tinue  exit return    trap        :    eval export    set  unset
              break     exec readonly  shift

       Additional ksh special commands

              lw(8m)fB    lw(8m)fB    lw(8m)fB     lw(8m)fB     lw(8m)fB     .
              builtin   times     typeset

       Very special commands (non-posix mode)

              lw(8m)fB  lw(8m)fB lw(8m)fB lw(8m)fB lw(8m)fB .  alias     read-
              only  set  typeset

       POSIX regular commands

              lw(8m)fB lw(8m)fB lw(8m)fB lw(8m)fB lw(8m)fB  .   alias     com-
              mand   fg   kill umask     bg   false     getopts   read unalias
              cd   fc   jobs true wait

       Additional ksh regular commands

              lw(8m)fB    lw(8m)fB    lw(8m)fB     lw(8m)fB     lw(8m)fB     .
              [    let  pwd  ulimit echo print     test whence

       In  the  future, the additional ksh special and regular commands may be
       treated differently from the POSIX special and regular commands.

       Once the type of the command has  been  determined,  any  command  line
       parameter  assignments  are  performed and exported for the duration of
       the command.

       The following describes the special and regular built-in commands:

       . file [arg1 ...]
              Execute the commands in file in the  current  environment.   The
              file  is  searched for in the directories of PATH.  If arguments
              are given, the positional parameters may be used to access  them
              while  file  is  being executed.  If no arguments are given, the
              positional parameters are those of the environment  the  command
              is used in.

       : [ ... ]
              The null command.  Exit status is set to zero.

       alias [ -d | ±t [-r] ] [±px] [±] [name1[=value1] ...]
              Without  arguments, alias lists all aliases.  For any name with-
              out a value, the existing alias is  listed.   Any  name  with  a
              value defines an alias (see Aliases above).

              When  listing  aliases,  one  of  two formats is used: normally,
              aliases are listed as name=value,  where  value  is  quoted;  if
              options were preceded with + or a lone + is given on the command
              line, only name is printed.  In addition, if the  -p  option  is
              used, each alias is prefixed with the string "alias ".

              The -x option sets (+x clears) the export attribute of an alias,
              or, if no names are given, lists the  aliases  with  the  export
              attribute (exporting an alias has no affect).

              The   -t  option  indicates  that  tracked  aliases  are  to  be
              listed/set (values specified on the command line are ignored for
              tracked  aliases).   The  -r  option  indicates that all tracked
              aliases are to be reset.

              The -d causes directory aliases, which are used in tilde  expan-
              sion, to be listed or set (see Tilde Expansion above).

       bg [job ...]
              Resume  the  specified  stopped job(s) in the background.  If no
              jobs are specified, %+ is assumed.  This command is only  avail-
              able  on  systems  which  support  job control.  See Job Control
              below for more information.

       bind [-l] [-m] [key[=editing-command] ...]
              Set  or  view  the  current  emacs  command  editing  key  bind-
              ings/macros.   See  Emacs  Editing  Mode  below  for  a complete
              description.

       break [level]
              break exits the levelth inner most for, select, until, or  while
              loop.  level defaults to 1.

       builtin command [arg1 ...]
              Execute the built-in command command.

       cd [-LP] [dir]
              Set  the  working  directory to dir.  If the parameter CDPATH is
              set, it lists directories to search in for dir.  An empty  entry
              in the CDPATH entry means the current directory.  If a non-empty
              directory from CDPATH  is  used,  the  resulting  full  path  is
              printed  to standard output.  If dir is missing, the home direc-
              tory $HOME is used.  If dir is -, the previous working directory
              is  used (see OLDPWD parameter).  If -L option (logical path) is
              used or if the physical option (see  set  command  below)  isn't
              set,  references  to .. in dir are relative to the path used get
              to the directory.  If -P option (physical path) is  used  or  if
              the  physical  option  is  set, .. is relative to the filesystem
              directory tree.  The PWD and OLDPWD parameters  are  updated  to
              reflect the current and old wording directory, respectively.

       cd [-LP] old new
              The  string new is substituted for old in the current directory,
              and the shell attempts to change to the new directory.

       command [-pvV] cmd [arg1 ...]
              If neither the -v nor -V options  are  given,  cmd  is  executed
              exactly  as  if  the  command  had  not been specified, with two
              exceptions: first, cmd cannot be a shell function,  and  second,
              special  built-in  commands  lose their specialness (i.e., redi-
              rection and utility errors do not cause the shell to  exit,  and
              command  assignments  are  not  permanent).  If the -p option is
              given, a default search path is  used  instead  of  the  current
              value  of  PATH  (the actual value of the default path is system
              dependent: on POSIXish systems, it is the value returned by
                                      getconf CS_PATH
              ).

              If the -v option is given, instead of executing cmd, information
              about  what would be executed is given (and the same is done for
              arg1 ...): for special and regular built-in commands  and  func-
              tions,  their  names  are simply printed, for aliases, a command
              that defines them is printed, and for commands found by  search-
              ing the PATH parameter, the full path of the command is printed.
              If no command is found, (i.e., the path search  fails),  nothing
              is  printed  and  command  exits with a non-zero status.  The -V
              option is like the -v option, except it is more verbose.

       continue [levels]
              continue jumps to the beginning of the levelth inner  most  for,
              select, until, or while loop.  level defaults to 1.

       echo [-neE] [arg ...]
              Prints  its  arguments  (separated by spaces) followed by a new-
              line, to standard out.  The newline is suppressed if any of  the
              arguments  contain the backslash sequence \c.  See print command
              below for a list of other backslash sequences  that  are  recog-
              nized.

              The  options  are  provided  for  compatibility  with  BSD shell
              scripts: -n suppresses the trailing newline,  -e  enables  back-
              slash interpretation (a no-op, since this is normally done), and
              -E suppresses backslash interpretation.

       eval command ...
              The arguments are concatenated (with  spaces  between  them)  to
              form a single string which the shell then parses and executes in
              the current environment.

       exec [command [arg ...]]
              The command is executed without  forking,  replacing  the  shell
              process.

              If  no  arguments are given, any IO redirection is permanent and
              the shell is not replaced.  Any file descriptors greater than  2
              which are opened or dup(2)-ed in this way are not made available
              to other executed commands (i.e., commands that are not built-in
              to the shell).  Note that the Bourne shell differs here: it does
              pass these file descriptors on.

       exit [status]
              The shell exits with the specified exit status.   If  status  is
              not  specified,  the  exit  status is the current value of the ?
              parameter.

       export [-p] [parameter[=value]] ...
              Sets the export attribute of  the  named  parameters.   Exported
              parameters  are  passed in the environment to executed commands.
              If values are specified, the named parameters also assigned.

              If no parameters are specified, the names of all parameters with
              the  export  attribute  are  printed one per line, unless the -p
              option is used, in  which  case  export  commands  defining  all
              exported parameters, including their values, are printed.

       false  A command that exits with a non-zero status.

       fc [-e editor | -l [-n]] [-r] [first [last]]
              first  and  last select commands from the history.  Commands can
              be selected by history number, or a string specifying  the  most
              recent  command  starting with that string.  The -l option lists
              the command on stdout, and -n inhibits the default command  num-
              bers.   The  -r  option reverses the order of the list.  Without
              -l, the selected commands are edited  by  the  editor  specified
              with  the -e option, or if no -e is specified, the editor speci-
              fied by the FCEDIT parameter (if  this  parameter  is  not  set,
              /bin/ed is used), and then executed by the shell.

       fc [-e - | -s] [-g] [old=new] [prefix]
              Re-execute   the  selected  command  (the  previous  command  by
              default) after performing the optional substitution of old  with
              new.   If  -g  is specified, all occurrences of old are replaced
              with new.  This command is usually accessed with the  predefined
              alias r='fc -e -'.

       fg [job ...]
              Resume  the  specified job(s) in the foreground.  If no jobs are
              specified, %+ is assumed.  This command  is  only  available  on
              systems  which  support  job control.  See Job Control below for
              more information.

       getopts optstring name [arg ...]
              getopts is used by shell procedures to parse the specified argu-
              ments  (or positional parameters, if no arguments are given) and
              to check for legal options.  optstring contains the option  let-
              ters that getopts is to recognize.  If a letter is followed by a
              colon, the option is expected to have an argument.  Options that
              do  not  take arguments may be grouped in a single argument.  If
              an option takes an argument and the option character is not  the
              last  character of the argument it is found in, the remainder of
              the argument is taken to be the  option's  argument,  otherwise,
              the next argument is the option's argument.

              Each  time  getopts is invoked, it places the next option in the
              shell parameter name and the index of the next  argument  to  be
              processed  in  the  shell  parameter  OPTIND.  If the option was
              introduced with a +, the option placed in name is prefixed  with
              a  +.  When an option requires an argument, getopts places it in
              the shell parameter OPTARG.  When an illegal option or a missing
              option  argument  is  encountered  a question mark or a colon is
              placed in name (indicating an illegal option  or  missing  argu-
              ment,  respectively)  and  OPTARG is set to the option character
              that caused the problem.  An error message is  also  printed  to
              standard error if optstring does not begin with a colon.

              When the end of the options is encountered, getopts exits with a
              non-zero exit status.  Options end  at  the  first  (non-option)
              argument  that does not start with a -, or when a -- argument is
              encountered.

              Option parsing can be reset by setting OPTIND to 1 (this is done
              automatically  whenever  the  shell  or  a  shell  procedure  is
              invoked).

              Warning: Changing the value of the shell parameter OPTIND  to  a
              value other than 1, or parsing different sets of arguments with-
              out resetting OPTIND may lead to unexpected results.

       hash [-r] [name ...]
              Without arguments, any hashed executable command  pathnames  are
              listed.   The -r option causes all hashed commands to be removed
              from the hash table.  Each name is searched as  if  it  where  a
              command  name and added to the hash table if it is an executable
              command.

       jobs [-lpn] [job ...]
              Display information about the specified jobs;  if  no  jobs  are
              specified,  all jobs are displayed.  The -n option causes infor-
              mation to be displayed only for jobs  that  have  changed  state
              since  the  last  notification.   If  the -l option is used, the
              process-id of each process in a job  is  also  listed.   The  -p
              option  causes only the process group of each job to be printed.
              See Job Control below for the format of job  and  the  displayed
              job.

       kill [-s signame | -signum | -signame ] { job | pid | -pgrp } ...
              Send the specified signal to the specified jobs, process ids, or
              process groups.  If no signal is specified, the signal  TERM  is
              sent.   If  a  job is specified, the signal is sent to the job's
              process group.  See Job Control below for the format of job.

       kill -l [exit-status ...]
              Print the name of the signal that killed a process which  exited
              with  the  specified  exit-statuses.  If no arguments are speci-
              fied, a list of all the  signals,  their  numbers  and  a  short
              description of them are printed.

       let [expression ...]
              Each  expression is evaluated, see Arithmetic Expressions above.
              If all expressions are successfully evaluated, the  exit  status
              is  0  (1)  if the last expression evaluated to non-zero (zero).
              If an error occurs  during  the  parsing  or  evaluation  of  an
              expression,  the  exit  status is greater than 1.  Since expres-
              sions may need to be quoted, (( expr )) is syntactic  sugar  for
              let "expr".

       print [-nprsun | -R [-en]] [argument ...]
              Print  prints its arguments on the standard output, separated by
              spaces, and terminated with a newline.  The -n option suppresses
              the  newline.   By  default,  certain  C escapes are translated.
              These include \b, \f, \n, \r, \t, \v, and \0### (# is  an  octal
              digit, of which there may be 0 to 3).  \c is equivalent to using
              the -n option.  \ expansion may be inhibited with the -r option.
              The  -s  option  prints  to the history file instead of standard
              output, the -u option prints to file descriptor n (n defaults to
              1  if  omitted), and the -p option prints to the co-process (see
              Co-Processes above).

              The -R option is used to emulate, to some degree, the  BSD  echo
              command, which does not process \ sequences unless the -e option
              is given.  As above, the -n option suppresses the trailing  new-
              line.

       pwd [-LP]
              Print the present working directory.  If -L option is used or if
              the physical option (see set command below) isn't set, the logi-
              cal  path  is  printed (i.e., the path used to cd to the current
              directory).  If -P option (physical path)  is  used  or  if  the
              physical  option is set, the path determined from the filesystem
              (by following ..  directories to the root directory) is printed.

       read [-prsun] [parameter ...]
              Reads  a  line  of  input from standard input, separate the line
              into fields using the IFS parameter  (see  Substitution  above),
              and assign each field to the specified parameters.  If there are
              more parameters than fields, the extra  parameters  are  set  to
              null,  or  alternatively,  if there are more fields than parame-
              ters, the  last  parameter  is  assigned  the  remaining  fields
              (inclusive  of  any  separating  spaces).   If no parameters are
              specified, the REPLY parameter is used.  If the input line  ends
              in a backslash and the -r option was not used, the backslash and
              newline are stripped and more input is read.   If  no  input  is
              read, read exits with a non-zero status.

              The  first  parameter  may  have  a  question  mark and a string
              appended to it, in which case the string is  used  as  a  prompt
              (printed  to  standard  error  before  any input is read) if the
              input is a tty (e.g., read nfoo?'number of foos: ').

              The -un and -p options cause input to be read from file descrip-
              tor n or the current co-process (see Co-Processes above for com-
              ments on this), respectively.  If the -s option is  used,  input
              is saved to the history file.

       readonly [-p] [parameter[=value]] ...
              Sets  the readonly attribute of the named parameters.  If values
              are given,  parameters  are  set  to  them  before  setting  the
              attribute.   Once  a  parameter  is  made readonly, it cannot be
              unset and its value cannot be changed.

              If no parameters are specified, the names of all parameters with
              the  readonly  attribute are printed one per line, unless the -p
              option is used, in which case  readonly  commands  defining  all
              readonly parameters, including their values, are printed.

       return [status]
              Returns  from  a  function or . script, with exit status status.
              If no status is given, the exit status of the last executed com-
              mand is used.  If used outside of a function or . script, it has
              the same effect as exit.  Note that pdksh  treats  both  profile
              and  $ENV files as . scripts, while the original Korn shell only
              treats profiles as . scripts.

       set [±abCefhkmnpsuvxX] [±o [option]] [±A name] [--] [arg ...]
              The set command can be used  to  set  (-)  or  clear  (+)  shell
              options,  set the positional parameters, or set an array parame-
              ter.  Options can be changed using the ±o option  syntax,  where
              option  is the long name of an option, or using the ±letter syn-
              tax, where letter is the option's single letter  name  (not  all
              options  have  a single letter name).  The following table lists
              both option letters (if they exist) and long names along with  a
              description of what the option does.


              expand;  afB  lfB lw(3i).  -A        T{ Sets the elements of the
              array parameter name to arg ...; If -A is  used,  the  array  is
              reset (i.e., emptied) first; if +A is used, the first N elements
              are set (where N is the number  of  args),  the  rest  are  left
              untouched.   T} -a   allexport T{ all new parameters are created
              with the export attribute T} -b   notify    T{ Print job notifi-
              cation  messages  asynchronously,  instead  of  just  before the
              prompt.   Only  used  if  job  control  is  enabled  (-m).    T}
              -C   noclobber T{  Prevent > redirection from overwriting exist-
              ing  files  (>|  must  be  used  to  force  an  overwrite).   T}
              -e   errexit   T{ Exit (after executing the ERR trap) as soon as
              an error occurs or a command fails (i.e., exits with a  non-zero
              status).   This  does not apply to commands whose exit status is
              explicitly tested by a shell construct such as if, until, while,
              &&  or  ||  statements.  T} -f   noglob    T{ Do not expand file
              name patterns.  T} -h   trackall  T{ Create tracked aliases  for
              all  executed  commands  (see Aliases above).  On by default for
              non-interactive shells.  T} -i   interactive    T{ Enable inter-
              active  mode  -  this  can  only  be set/unset when the shell is
              invoked.  T} -k   keyword   T{ Parameter assignments are  recog-
              nized  anywhere in a command.  T} -l   login     T{ The shell is
              a login shell - this can only be set/unset  when  the  shell  is
              invoked  (see Shell Startup above).  T} -m   monitor   T{ Enable
              job   control   (default   for    interactive    shells).     T}
              -n   noexec    T{  Do  not  execute  any  commands  - useful for
              checking the syntax of scripts  (ignored  if  interactive).   T}
              -p   privileged     T{  Set  automatically  if,  when  the shell
              starts, the real uid or gid does not match the effective uid  or
              gid, respectively.  See Shell Startup above for a description of
              what this means.  T}  -r   restricted     T{  Enable  restricted
              mode  -- this option can only be used when the shell is invoked.
              See Shell Startup above for a description of  what  this  means.
              T} -s   stdin     T{ If used when the shell is invoked, commands
              are read from standard input.  Set automatically if the shell is
              invoked with no arguments.

              When  -s  is  used  in  the set command, it causes the specified
              arguments to be sorted before assigning them to  the  positional
              parameters  (or  to  array  name, if -A is used).  T} -u   noun-
              set   T{ Referencing of an unset  parameter  is  treated  as  an
              error,  unless  one  of  the  -,  +  or = modifiers is used.  T}
              -v   verbose   T{ Write shell input to standard error as  it  is
              read.  T} -x   xtrace    T{ Print commands and parameter assign-
              ments when they are executed, preceded by the value of PS4.   T}
              -X   markdirs  T{ Mark directories with a trailing / during file
              name generation.  T}      bgnice    T{ Background jobs  are  run
              with  lower  priority.   T}       braceexpand    T{ Enable brace
              expansion (aka, alternation).  T}      emacs     T{  Enable  BRL
              emacs-like  command  line editing (interactive shells only); see
              Emacs Editing Mode.  T}      emacs-usemeta  T{ In emacs command-
              line  editing, use the 8th bit as meta (^[) prefix.  This is the
              default if LC_CTYPE is unset or  POSIX  respectively  C.   8  T}
                   gmacs     T{ Enable gmacs-like (Gosling emacs) command line
              editing (interactive shells only); currently identical to  emacs
              editing  except  that  transpose (^T) acts slightly differently.
              T}      ignoreeof T{ The shell will not (easily)  exit  on  when
              end-of-file  is  read,  exit  must  be  used.  To avoid infinite
              loops, the shell will exit if eof is read 13 times in a row.  T}
                   nohup     T{  Do  not  kill  running jobs with a HUP signal
              when a login shell exists.  Currently set by default,  but  this
              will  change  in  the  future to be compatible with the original
              Korn shell (which doesn't have this option, but  does  send  the
              HUP  signal).   T}      nolog     T{ No effect - in the original
              Korn shell, this prevents function definitions from being stored
              in the history file.  T}      physical  T{ Causes the cd and pwd
              commands to use `physical' (i.e., the filesystem's) ..  directo-
              ries  instead of `logical' directories (i.e.,  the shell handles
              .., which allows the user to be oblivious of  symlink  links  to
              directories).   Clear by default.  Note that setting this option
              does not effect the current value of the PWD parameter; only the
              cd  command  changes PWD.  See the cd and pwd commands above for
              more details.  T}       posix     T{  Enable  posix  mode.   See
              POSIX  Mode  above.  T}      vi   T{ Enable vi-like command line
              editing (interactive  shells  only).   T}       viraw     T{  No
              effect  -  in the original Korn shell, unless viraw was set, the
              vi command line mode would let the tty driver do the work  until
              ESC  (^[)  was  entered.   pdksh  is  always  in viraw mode.  T}
                   vi-esccomplete T{ In vi command line editing, do command  /
              file  name  completion  when  escape  (^[) is entered in command
              mode.  T}      vi-show8  T{ Prefix characters  with  the  eighth
              bit set with `M-'.  If this option is not set, characters in the
              range 128-160 are printed as is, which may cause  problems.   T}
                   vi-tabcomplete T{  In vi command line editing, do command /
              file name completion when tab (^I) is entered  in  insert  mode.
              This is the default.  T}

              These  options  can  also  be used upon invocation of the shell.
              The current set of options (with single  letter  names)  can  be
              found  in the parameter -.  set -o with no option name will list
              all the options and whether each is on or off; set +o will print
              the long names of all options that are currently on.

              Remaining  arguments,  if any, are positional parameters and are
              assigned, in order, to the positional parameters  (i.e.,  1,  2,
              etc.).   If options are ended with -- and there are no remaining
              arguments, all positional parameters are cleared.  If no options
              or  arguments  are  given,  then  the  values  of  all names are
              printed.  For unknown historical reasons, a  lone  -  option  is
              treated specially: it clears both the -x and -v options.

       shift [number]
              The positional parameters number+1, number+2 etc. are renamed to
              1, 2, etc.  number defaults to 1.

       test expression

       [ expression ]
              test evaluates the expression and returns zero status if true, 1
              if  false, and greater than 1 if there was an error.  It is nor-
              mally used as the condition command of if and while  statements.
              The following basic expressions are available:


              afB  ltw(3.2i).   str  T{  str  has  non-zero length.  Note that
              there is the potential for problems if str turns out  to  be  an
              operator (e.g., -r) - it is generally better to use a test like
                                      [ X"str" != X ]
              instead  (double  quotes are used in case str contains spaces or
              file globing characters).  T} -r file   T{ file  exists  and  is
              readable.   T}  -w file   T{ file exists and is writable.  T} -x
              file   T{ file exists and is executable.  T} -a  file   T{  file
              exists.  T} -e file   T{ file exists.  T} -f file   T{ file is a
              regular file.  T} -d file   T{  file  is  a  directory.   T}  -c
              file   T{  file  is a character special device.  T} -b file   T{
              file is a block special device.  T} -p file   T{ file is a named
              pipe.   T}  -u  file   T{ file's mode has setuid bit set.  T} -g
              file   T{ file's mode has  setgid  bit  set.   T}  -k  file   T{
              file's  mode  has  sticky  bit set.  T} -s file   T{ file is not
              empty.  T} -O file   T{ file's owner is  the  shell's  effective
              user-ID.   T} -G file   T{ file's group is the shell's effective
              group-ID.  T} -h file   T{ file  is  a  symbolic  link.   T}  -H
              file   T{  file is a context dependent directory (only useful on
              HP-UX).  T} -L  file   T{  file  is  a  symbolic  link.   T}  -S
              file   T{ file is a socket.  T} -o option T{ shell option is set
              (see set command above for list of options).  As a  non-standard
              extension,  if  the option starts with a !, the test is negated;
              the test always fails if option doesn't exist (thus
                                   [ -o foo -o -o !foo ]
              returns true if and only if option foo  exists).   T}  file  -nt
              file  T{  first  file  is  newer  than second file or first file
              exists and the second file does not.  T} file -ot file  T{ first
              file  is  older  than  second file or second file exists and the
              first file does not.  T} file -ef file  T{  first  file  is  the
              same  file as second file.  T} -t [fd]   T{ file descriptor is a
              tty device.  If the posix option (set -o posix, see  POSIX  Mode
              above) is not set, fd may be left out, in which case it is taken
              to be 1 (the behaviour differs due to the  special  POSIX  rules
              described  below).   T}  string    T{  string  is not empty.  T}
              -z string T{ string is empty.  T}  -n string T{  string  is  not
              empty.    T}   string = string     T{  strings  are  equal.   T}
              string == string    T{     strings      are      equal.       T}
              string != string    T{   strings   are   not   equal.   T}  num-
              ber -eq number   T{ numbers compare equal.   T}  number -ne num-
              ber   T{  numbers  compare not equal.  T} number -ge number   T{
              numbers compare  greater  than  or  equal.   T}  number -gt num-
              ber   T{  numbers  compare  greater  than.   T}  number -le num-
              ber   T{ numbers compare less than or equal.  T} number -lt num-
              ber   T{ numbers compare less than.  T}

              The  above  basic  expressions,  in  which  unary operators have
              precedence over binary operators, may be combined with the  fol-
              lowing operators (listed in increasing order of precedence):


              afB  l.   expr -o expr   logical or expr -a expr   logical and !
              expr    logical not ( expr )  grouping

              On operating systems not supporting /dev/fd/n devices  (where  n
              is  a  file descriptor number), the test command will attempt to
              fake it for all tests that  operate  on  files  (except  the  -e
              test).   I.e.,  [  -w  /dev/fd/2 ] tests if file descriptor 2 is
              writable.

              Note that some special rules are applied (courtesy of POSIX)  if
              the number of arguments to test or [ ... ] is less than five: if
              leading ! arguments can be stripped such that only one  argument
              remains  then  a string length test is performed (again, even if
              the argument is a unary operator); if leading ! arguments can be
              stripped  such  that three arguments remain and the second argu-
              ment is a binary operator, then the  binary  operation  is  per-
              formed (even if first argument is a unary operator, including an
              unstripped !).

              Note: A common mistake is to use if [ $foo = bar ]  which  fails
              if  parameter  foo  is  null or unset, if it has embedded spaces
              (i.e., IFS characters), or if it is a unary operator like  !  or
              -n.  Use tests like if [ "X$foo" = Xbar ] instead.

       time [-p] [ pipeline ]
              If  a  pipeline is given, the times used to execute the pipeline
              are reported.  If no pipeline is given, then the user and system
              time  used  by the shell itself, and all the commands it has run
              since it was started, are reported.  The times reported are  the
              real time (elapsed time from start to finish), the user CPU time
              (time spent running in user mode) and the system CPU time  (time
              spent  running  in kernel mode).  Times are reported to standard
              error; the format of the output is:
                  0.00s real     0.00s user     0.00s system
              unless the -p option is given (only possible if  pipeline  is  a
              simple command), in which case the output is slightly longer:
                  real   0.00
                  user   0.00
                  sys    0.00
              (the  number of digits after the decimal may vary from system to
              system).  Note that simple redirections of standard error do not
              effect the output of the time command:
                                   time sleep 1 2> afile
                                 { time sleep 1; } 2> afile
              times for the first command do not go to afile, but those of the
              second command do.

       times  Print the accumulated user and system times used  by  the  shell
              and by processes which have exited that the shell started.

       trap [handler signal ...]
              Sets  trap handler that is to be executed when any of the speci-
              fied signals are received.  Handler is  either  a  null  string,
              indicating  the signals are to be ignored, a minus (-), indicat-
              ing that the default action is to be taken for the signals  (see
              signal(3)),  or  a string containing shell commands to be evalu-
              ated and executed at the first opportunity (i.e., when the  cur-
              rent  command completes, or before printing the next PS1 prompt)
              after receipt of one of the signals.  Signal is the  name  of  a
              signal  (e.g.,  PIPE  or  ALRM) or the number of the signal (see
              kill -l command above).  There are  two  special  signals:  EXIT
              (also  known as 0), which is executed when the shell is about to
              exit, and ERR which is executed after an error occurs (an  error
              is  something  that  would  cause the shell to exit if the -e or
              errexit option were set -- see set command  above).   EXIT  han-
              dlers  are executed in the environment of the last executed com-
              mand.  Note that for non-interactive shells,  the  trap  handler
              cannot  be  changed for signals that were ignored when the shell
              started.

              With no arguments, trap lists, as a series of trap commands, the
              current  state  of  the traps that have been set since the shell
              started.  Note that the output of trap can not be usefully piped
              to  another  process  (an  artifact  of  the fact that traps are
              cleared when subprocesses are created).

              The original Korn shell's DEBUG trap and the handling of ERR and
              EXIT traps in functions are not yet implemented.

       true   A command that exits with a zero value.

       typeset  [[±Ulprtux]  [-L[n]]  [-R[n]]  [-Z[n]]  [-i[n]]  |  -f [-tux]]
       [name[=value] ...]
              Display  or  set  parameter attributes.  With no name arguments,
              parameter attributes are displayed: if no options arg used,  the
              current attributes of all parameters are printed as typeset com-
              mands; if an option is given (or - with no  option  letter)  all
              parameters  and  their  values with the specified attributes are
              printed; if options are introduced with +, parameter values  are
              not printed.

              If name arguments are given, the attributes of the named parame-
              ters are set (-) or cleared  (+).   Values  for  parameters  may
              optionally  be specified.  If typeset is used inside a function,
              any newly created parameters are local to the function.

              When -f is used, typeset operates on  the  attributes  of  func-
              tions.  As with parameters, if no names are given, functions are
              listed with their values (i.e., definitions) unless options  are
              introduced  with  +,  in  which case only the function names are
              reported.


              expand; afB lw(4.5i).  -Ln  T{ Left justify attribute: n  speci-
              fies  the field width.  If n is not specified, the current width
              of a parameter (or the width of its  first  assigned  value)  is
              used.   Leading  white  space  (and  zeros,  if used with the -Z
              option) is stripped.  If necessary, values are either  truncated
              or  space  padded to fit the field width.  T} -Rn  T{ Right jus-
              tify attribute: n specifies the field width.  If n is not speci-
              fied,  the  current  width  of  a parameter (or the width of its
              first  assigned  value)  is  used.   Trailing  white  space  are
              stripped.   If  necessary, values are either stripped of leading
              characters or space padded to make them fit the field width.  T}
              -Zn  T{  Zero  fill  attribute: if not combined with -L, this is
              the same as -R, except zero padding is  used  instead  of  space
              padding.   T} -in  T{ integer attribute: n specifies the base to
              use when displaying the integer  (if  not  specified,  the  base
              given  in  the  first assignment is used).  Parameters with this
              attribute may be assigned values containing  arithmetic  expres-
              sions.   T}  -U   T{  unsigned  integer  attribute: integers are
              printed as unsigned values (only useful when combined  with  the
              -i  option).  This option is not in the original Korn shell.  T}
              -f   T{ Function  mode:  display  or  set  functions  and  their
              attributes,  instead  of  parameters.   T}  -l   T{  Lower  case
              attribute: all  upper case characters in values are converted to
              lower  case.   (In the original Korn shell, this parameter meant
              `long integer' when used with the -i option).  T} -p   T{  Print
              complete  typeset  commands  that  can  be used to re-create the
              attributes (but not the values)  of  parameters.   This  is  the
              default  action  (option  exists  for  ksh93 compatibility).  T}
              -r   T{ Readonly attribute: parameters with the  this  attribute
              may not be assigned to or unset.  Once this attribute is set, it
              can not be turned off.  T} -t   T{ Tag attribute: has no meaning
              to the shell; provided for application use.

              For  functions,  -t is the trace attribute.  When functions with
              the trace attribute are executed, the xtrace (-x)  shell  option
              is  temporarily turned on.  T} -u   T{ Upper case attribute: all
              lower case characters in values are  converted  to  upper  case.
              (In  the  original  Korn  shell,  this parameter meant `unsigned
              integer' when used with the -i option, which  meant  upper  case
              letters  would never be used for bases greater than 10.  See the
              -U option).

              For functions, -u is the  undefined  attribute.   See  Functions
              above   for   the  implications  of  this.   T}  -x   T{  Export
              attribute: parameters (or functions) are placed in the  environ-
              ment  of  any  executed  commands.   Exported  functions are not
              implemented yet.  T}

       ulimit [-abcdfHlmnpsStvw] [value]
              Display or set process limits.  If no options are used, the file
              size  limit (-f) is assumed.  value, if specified, may be either
              be an arithmetic expression or the word unlimited.   The  limits
              affect  the shell and any processes created by the shell after a
              limit is imposed.  Note that some systems may not  allow  limits
              to  be increased once they are set.  Also note that the types of
              limits available are system dependent - some systems  have  only
              the -f limit.

              -a     Displays  all  limits; unless -H is used, soft limits are
                     displayed.

              -H     Set the hard limit only (default is to set both hard  and
                     soft limits).

              -S     Set  the soft limit only (default is to set both hard and
                     soft limits).

              -b     Impose a size limit of n bytes  on  the  size  of  socket
                     buffers.

              -c     Impose  a  size  limit  of  n  blocks on the size of core
                     dumps.

              -d     Impose a size limit of n kbytes on the size of  the  data
                     area.

              -f     Impose  a  size limit of n blocks on files written by the
                     shell and its child processes (files of any size  may  be
                     read).

              -l     Impose  a  limit  of  n  kbytes  on  the amount of locked
                     (wired) physical memory.

              -m     Impose a limit of n kbytes on the amount of physical mem-
                     ory used.

              -n     Impose  a limit of n file descriptors that can be open at
                     once.

              -p     Impose a limit of n processes that can be run by the user
                     at any one time.

              -s     Impose  a size limit of n kbytes on the size of the stack
                     area.

              -t     Impose a time limit of n CPU seconds to be used  by  each
                     process.

              -v     Impose  a limit of n kbytes on the amount of virtual mem-
                     ory used; on some systems this is the  maximum  allowable
                     virtual address (in bytes, not kbytes).

              -w     Impose  a  limit  of n kbytes on the amount of swap space
                     used.

              As far as ulimit is concerned, a block is 512 bytes.

       umask [-S] [mask]
              Display or set the file permission creation mask, or umask  (see
              umask(2)).   If the -S option is used, the mask displayed or set
              is symbolic, otherwise it is an octal number.

              Symbolic masks are like those used by chmod(1):
                     [ugoa]{{=+-}{rwx}*}+[,...]
              in which the first group of characters is the who part, the sec-
              ond  group  is the op part, and the last group is the perm part.
              The who part specifies which part of the umask is  to  be  modi-
              fied.  The letters mean:

                     u      the user permissions

                     g      the group permissions

                     o      the other permissions (non-user, non-group)

                     a      all permissions (user, group and other)

              The  op  part  indicates how the who permissions are to be modi-
              fied:

                     =      set

                     +      added to

                     -      removed from

              The perm part specifies which permissions are to be  set,  added
              or removed:

                     r      read permission

                     w      write permission

                     x      execute permission

              When symbolic masks are used, they describe what permissions may
              be made available (as opposed to octal masks in which a set  bit
              means  the  corresponding  bit  is  to  be  cleared).   Example:
              `ug=rwx,o=' sets  the  mask  so  files  will  not  be  readable,
              writable  or  executable by `others', and is equivalent (on most
              systems) to the octal mask `07'.

       unalias [-adt] [name1 ...]
              The aliases for the given names are removed.  If the  -a  option
              is  used,  all aliases are removed.  If the -t or -d options are
              used, the indicated operations are carried  out  on  tracked  or
              directory aliases, respectively.

       unset [-fv] parameter ...
              Unset  the named parameters (-v, the default) or functions (-f).
              The exit status is  non-zero  if  any  of  the  parameters  were
              already unset, zero otherwise.

       wait [job]
              Wait  for  the  specified  job(s) to finish.  The exit status of
              wait is that of the last specified  job:  if  the  last  job  is
              killed  by  a signal, the exit status is 128 + the number of the
              signal (see kill -l exit-status above); if  the  last  specified
              job  can't  be  found  (because it never existed, or had already
              finished), the exit status of wait  is  127.   See  Job  Control
              below  for  the format of job.  Wait will return if a signal for
              which a trap has been set is received, or if a HUP, INT or  QUIT
              signal is received.

              If  no  jobs are specified, wait waits for all currently running
              jobs (if any) to finish and exits with a zero  status.   If  job
              monitoring  is enabled, the completion status of jobs is printed
              (this is not the case when jobs are explicitly specified).

       whence [-pv] [name ...]
              For each name, the type of command  is  listed  (reserved  word,
              built-in, alias, function, tracked alias or executable).  If the
              -p option is used, a path search done even if name is a reserved
              word,  alias,  etc.  Without the -v option, whence is similar to
              command -v except that whence will find reserved words and won't
              print  aliases  as alias commands; with the -v option, whence is
              the same as command -V.  Note that for  whence,  the  -p  option
              does  not  affect  the search path used, as it does for command.
              If the type of one or more of the names could not be determined,
              the exit status is non-zero.

   Job Control
       Job  control refers to the shell's ability to monitor and control jobs,
       which are processes or groups of  processes  created  for  commands  or
       pipelines.   At  a  minimum, the shell keeps track of the status of the
       background (i.e., asynchronous) jobs that currently exist; this  infor-
       mation  can  be  displayed  using  the jobs command.  If job control is
       fully enabled (using set -m or set -o monitor), as it is  for  interac-
       tive  shells,  the  processes  of a job are placed in their own process
       group, foreground jobs can be stopped by typing the  suspend  character
       from  the  terminal  (normally ^Z), jobs can be restarted in either the
       foreground or background, using the fg and bg  commands,  respectively,
       and  the  state  of the terminal is saved or restored when a foreground
       job is stopped or restarted, respectively.

       Note that only commands that create processes (e.g., asynchronous  com-
       mands,  subshell commands, and non-built-in, non-function commands) can
       be stopped; commands like read cannot be.

       When a job is created, it is assigned a  job-number.   For  interactive
       shells, this number is printed inside [..], followed by the process-ids
       of the processes in the job when an asynchronous command is run.  A job
       may  be  referred  to in bg, fg, jobs, kill and wait commands either by
       the process id of the last process in the command pipeline  (as  stored
       in the $! parameter) or by prefixing the job-number with a percent sign
       (%).  Other percent sequences can also be used to refer to jobs:


       expand; afB lw(4.5i).  %+   T{ The most recently stopped  job,  or,  if
       there  are  no  stopped  jobs, the oldest running job.  T} %%, %     T{
       Same as %+.  T} %-   T{ The job that would be the %+ job, if the  later
       did  not exist.  T} %n   T{ The job with job-number n.  T} %?string  T{
       The job containing the string string (an error occurs if multiple  jobs
       are  matched).  T} %string   T{ The job starting with string string (an
       error occurs if multiple jobs are matched).  T}

       When a job changes state (e.g., a background job finishes or foreground
       job is stopped), the shell prints the following status information:
              [number] flag status command
       where

        number
              is the job-number of the job.

        flag  is + or - if the job is the %+ or %- job, respectively, or space
              if it is neither.

        status
              indicates the current state of the job and can be

              Running
                     the job has neither stopped or exited (note that  running
                     does  not  necessarily  mean  consuming  CPU  time -- the
                     process could be blocked waiting for some event).

              Done [(number)]
                     the job exited.  number is the exit status  of  the  job,
                     which is omitted if the status is zero.

              Stopped [(signal)]
                     the job was stopped by the indicated signal (if no signal
                     is given, the job was stopped by SIGTSTP).

              signal-description [(core dumped)]
                     the job was  killed  by  a  signal  (e.g.,  Memory fault,
                     Hangup, etc. -- use kill -l for a list of signal descrip-
                     tions).  The (core dumped) message indicates the  process
                     created a core file.

        command
              is  the command that created the process.  If there are multiple
              processes in the job, then each process will have a line showing
              its command and possibly its status, if it is different from the
              status of the previous process.

       When an attempt is made to exit the shell while there are jobs  in  the
       stopped state, the shell warns the user that there are stopped jobs and
       does not exit.  If another attempt is  immediately  made  to  exit  the
       shell,  the  stopped  jobs  are  sent a HUP signal and the shell exits.
       Similarly, if the nohup option is not set and there  are  running  jobs
       when an attempt is made to exit a login shell, the shell warns the user
       and does not exit.  If another attempt is immediately made to exit  the
       shell, the running jobs are sent a HUP signal and the shell exits.

   Interactive Input Line Editing
       The  shell  supports three modes of reading command lines from a tty in
       an interactive session.  Which is used  is  controlled  by  the  emacs,
       gmacs and vi set options (at most one of these can be set at once).  If
       none of these options is enabled, the shell simply  reads  lines  using
       the  normal tty driver.  If the emacs or gmacs option is set, the shell
       allows emacs like editing of the command; similarly, if the  vi  option
       is  set,  the shell allows vi like editing of the command.  These modes
       are described in detail in the following sections.

       In these editing modes, if a line is longer that the screen width  (see
       COLUMNS parameter), a >, + or < character is displayed in the last col-
       umn indicating that there are more characters after, before and  after,
       or  before  the  current  position, respectively.  The line is scrolled
       horizontally as necessary.

   Emacs Editing Mode
       When the emacs  option  is  set,  interactive  input  line  editing  is
       enabled.   Warning: This mode is slightly different from the emacs mode
       in the original Korn shell and the 8th bit is stripped in  emacs  mode.
       In  this  mode various editing commands (typically bound to one or more
       control characters) cause immediate actions without waiting for a  new-
       line.  Several editing commands are bound to particular control charac-
       ters when the shell is invoked; these bindings can be changed using the
       following commands:

       bind   The current bindings are listed.

       bind string=[editing-command]
              The  specified  editing  command  is  bound to the given string,
              which should consist of a control character (which may be  writ-
              ten  using caret notation ^X), optionally preceded by one of the
              two prefix characters.  Future input of the  string  will  cause
              the  editing  command  to  be  immediately  invoked.   Note that
              although only two prefix characters (usually  ESC  and  ^X)  are
              supported, some multi-character sequences can be supported.  The
              following binds the arrow keys on an  ANSI  terminal,  or  xterm
              (these  are  in  the  default  bindings).  Of course some escape
              sequences won't work out quite this nicely:

              bind '^[['=prefix-2
              bind '^XA'=up-history
              bind '^XB'=down-history
              bind '^XC'=forward-char
              bind '^XD'=backward-char

       bind -l
              Lists the names of the functions to which keys may be bound.

       bind -m string=[substitute]
              The  specified  input  string  will  afterwards  be  immediately
              replaced by the given substitute string, which may contain edit-
              ing commands.

       The following is a list of editing commands available.   Each  descrip-
       tion  starts  with  the name of the command, a n, if the command can be
       prefixed with a count, and any keys the command is bound to by  default
       (written  using caret notation, e.g., ASCII ESC character is written as
       ^[).  A count prefix for a command is entered using the  sequence  ^[n,
       where  n is a sequence of 1 or more digits; unless otherwise specified,
       if a count is omitted, it defaults to 1.   Note  that  editing  command
       names  are  used only with the bind command.  Furthermore, many editing
       commands are useful only on  terminals  with  a  visible  cursor.   The
       default  bindings were chosen to resemble corresponding EMACS key bind-
       ings.  The users tty characters (e.g., ERASE) are bound  to  reasonable
       substitutes and override the default bindings.

       abort ^G
              Useful  as  a response to a request for a search-history pattern
              in order to abort the search.

       auto-insert n
              Simply causes the character to appear as  literal  input.   Most
              ordinary characters are bound to this.

       backward-char  n ^B
              Moves the cursor backward n characters.

       backward-word  n ^[B
              Moves the cursor backward to the beginning of a word; words con-
              sist of alphanumerics, underscore (_) and dollar ($).

       beginning-of-history ^[<
              Moves to the beginning of the history.

       beginning-of-line ^A
              Moves the cursor to the beginning of the edited input line.

       capitalize-word n ^[c, ^[C
              Uppercase the first character in the next n words,  leaving  the
              cursor  past the end of the last word.  If the current line does
              not begin with a comment character, one is added at  the  begin-
              ning  of the line and the line is entered (as if return had been
              pressed), otherwise the existing comment characters are  removed
              and the cursor is placed at the beginning of the line.

       complete ^[^[

       complete ^I
              Automatically completes as much as is unique of the command name
              or the file name containing the cursor.  If the entire remaining
              command or file name is unique a space is printed after its com-
              pletion, unless it is a  directory  name  in  which  case  /  is
              appended.   If there is no command or file name with the current
              partial word as its prefix, a bell character is output  (usually
              causing a audio beep).

       complete-command ^X^[
              Automatically completes as much as is unique of the command name
              having the partial word up to the cursor as its  prefix,  as  in
              the complete command described above.

       complete-file ^[^X
              Automatically  completes  as  much as is unique of the file name
              having the partial word up to the cursor as its  prefix,  as  in
              the complete command described above.

       complete-list ^[=
              List the possible completions for the current word.

       delete-char-backward n ERASE, ^?, ^H
              Deletes n characters before the cursor.

       delete-char-forward n
              Deletes n characters after the cursor.

       delete-word-backward n ^[ERASE, ^[^?, ^[^H, ^[h
              Deletes n words before the cursor.

       delete-word-forward n ^[d
              Deletes characters after the cursor up to the end of n words.

       down-history n ^N
              Scrolls  the history buffer forward n lines (later).  Each input
              line originally starts just after the last entry in the  history
              buffer,  so  down-history is not useful until either search-his-
              tory or up-history has been performed.

       downcase-word n ^[L, ^[l
              Lowercases the next n words.

       end-of-history ^[>
              Moves to the end of the history.

       end-of-line ^E
              Moves the cursor to the end of the input line.

       eot ^_ Acts as an end-of-file; this is useful because  edit-mode  input
              disables normal terminal input canonicalization.

       eot-or-delete n ^D
              Acts  as  eot if alone on a line; otherwise acts as delete-char-
              forward.

       error  Error (ring the bell).

       exchange-point-and-mark ^X^X
              Places the cursor where the mark is, and sets the mark to  where
              the cursor was.

       expand-file ^[*
              Appends  a  * to the current word and replaces the word with the
              result of performing file globbing on the  word.   If  no  files
              match the pattern, the bell is rung.

       forward-char n ^F
              Moves the cursor forward n characters.

       forward-word n ^[f
              Moves the cursor forward to the end of the nth word.

       goto-history n ^[g
              Goes to history number n.

       kill-line KILL
              Deletes the entire input line.

       kill-region ^W
              Deletes the input between the cursor and the mark.

       kill-to-eol n ^K
              Deletes the input from the cursor to the end of the line if n is
              not specified, otherwise deletes characters between  the  cursor
              and column n.

       list ^[?
              Prints  a sorted, columnated list of command names or file names
              (if any) that can complete the partial word containing the  cur-
              sor.  Directory names have / appended to them.

       list-command ^X?
              Prints  a sorted, columnated list of command names (if any) that
              can complete the partial word containing the cursor.

       list-file ^X^Y
              Prints a sorted, columnated list of file names (if any) that can
              complete  the  partial  word  containing  the cursor.  File type
              indicators are appended as described under list above.

       newline ^J, ^M
              Causes the current input line to be processed by the shell.  The
              current cursor position may be anywhere on the line.

       newline-and-next ^O
              Causes  the current input line to be processed by the shell, and
              the next line from history becomes the current  line.   This  is
              only useful after an up-history or search-history.

       no-op QUIT
              This does nothing.

       prefix-1 ^[
              Introduces a 2-character command sequence.

       prefix-2 ^X

       prefix-2 ^[[
              Introduces a 2-character command sequence.

       prev-hist-word n ^[., ^[_
              The  last  (nth) word of the previous command is inserted at the
              cursor.

       quote ^^
              The following character is taken literally  rather  than  as  an
              editing command.

       redraw ^L
              Reprints the prompt string and the current input line.

       search-character-backward n ^[^]
              Search  backward  in  the current line for the nth occurrence of
              the next character typed.

       search-character-forward n ^]
              Search forward in the current line for the nth occurrence of the
              next character typed.

       search-history ^R
              Enter  incremental  search  mode.   The internal history list is
              searched backwards for commands matching the input.  An  initial
              ^  in  the search string anchors the search.  The abort key will
              leave search mode.  Other commands will be executed after  leav-
              ing  search  mode.   Successive search-history commands continue
              searching backward to the next previous occurrence of  the  pat-
              tern.  The history buffer retains only a finite number of lines;
              the oldest are discarded as necessary.

       set-mark-command ^[<space>
              Set the mark at the cursor position.

       stuff  On systems supporting it, pushes the bound character  back  onto
              the  terminal  input  where it may receive special processing by
              the terminal handler.  This is useful for the BRL ^T mini-systat
              feature, for example.

       stuff-reset
              Acts like stuff, then aborts input the same as an interrupt.

       transpose-chars ^T
              If  at  the  end  of  line,  or if the gmacs option is set, this
              exchanges the two previous characters; otherwise,  it  exchanges
              the  previous  and  current  characters and moves the cursor one
              character to the right.

       up-history n ^P
              Scrolls the history buffer backward n lines (earlier).

       upcase-word n ^[U, ^[u
              Uppercases the next n words.

       version ^V
              Display the version of ksh.  The current edit buffer is restored
              as soon as any key is pressed (the key is then processed, unless
              it is a space).

       yank ^Y
              Inserts the most recently killed text string at the current cur-
              sor position.

       yank-pop ^[y
              Immediately after a yank, replaces the inserted text string with
              the next previous killed text string.

   Vi Editing Mode
       The vi command line editor in ksh has basically the  same  commands  as
       the vi editor (see vi(1)), with the following exceptions:

         ·    you start out in insert mode,

         ·    there  are  file  name and command completion commands (=, \, *,
              ^X, ^E, ^F and, optionally, <tab>),

         ·    the _ command is different (in ksh it is the last argument  com-
              mand, in vi it goes to the start of the current line),

         ·    the  /  and  G  commands move in the opposite direction as the j
              command

         ·    and commands which don't make sense in a single line editor  are
              not  available  (e.g.,  screen movement commands, ex : commands,
              etc.).

       Note that the ^X stands for control-X; also <esc>,  <space>  and  <tab>
       are used for escape, space and tab, respectively (no kidding).

       Like  vi, there are two modes: insert mode and command mode.  In insert
       mode, most characters are simply put in the buffer at the current  cur-
       sor  position  as  they are typed, however, some characters are treated
       specially.  In particular, the following characters are taken from cur-
       rent  tty  settings  (see stty(1)) and have their usual meaning (normal
       values are in parentheses): kill (^U), erase  (^?),  werase  (^W),  eof
       (^D), intr (^C) and quit (^\).  In addition to the above, the following
       characters are also treated specially in insert mode:

       expand; afB lw(4.5i).  ^H   T{ erases  previous  character  T}  ^V   T{
       literal next: the next character typed is not treated specially (can be
       used to insert the characters being described here) T} ^J ^M     T{ end
       of  line: the current line is read, parsed and executed by the shell T}
       <esc>     T{ puts the editor in command mode  (see  below)  T}  ^E   T{
       command  and  file  name enumeration (see below) T} ^F   T{ command and
       file name completion (see below).  If used twice in a row, the list  of
       possible completions is displayed; if used a third time, the completion
       is undone.  T} ^X   T{ command and file name expansion (see  below)  T}
       <tab>     T{  optional file name and command completion (see ^F above),
       enabled with set -o vi-tabcomplete T}

       In command mode, each character is interpreted as a  command.   Charac-
       ters  that  don't  correspond  to commands, are illegal combinations of
       commands or are commands that can't be carried out all cause beeps.  In
       the  following  command  descriptions, a n indicates the command may be
       prefixed by a number (e.g., 10l moves right 10 characters); if no  num-
       ber  prefix  is  used, n is assumed to be 1 unless otherwise specified.
       The term `current position' refers to the position between  the  cursor
       and the character preceding the cursor.  A `word' is a sequence of let-
       ters, digits and underscore characters or  a  sequence  of  non-letter,
       non-digit,  non-underscore,  non-white-space  characters  (e.g., ab2*&^
       contains two words) and a `big-word' is a sequence  of  non-white-space
       characters.

       Special ksh vi commands
              The  following  commands  are not in, or are different from, the
              normal vi file editor:

              n_     insert a space followed by the nth big-word from the last
                     command  in the history at the current position and enter
                     insert mode; if n is not  specified,  the  last  word  is
                     inserted.

              #      insert the comment character (#) at the start of the cur-
                     rent line and return the line to the shell (equivalent to
                     I#^J).

              ng     like G, except if n is not specified, it goes to the most
                     recent remembered line.

              nv     edit line n using the vi editor; if n is  not  specified,
                     the  current line is edited.  The actual command executed
                     is `fc -e ${VISUAL:-${EDITOR:-vi}} n'.

              * and ^X
                     command or file name expansion is applied to the  current
                     big-word  (with  an  appended  *, if the word contains no
                     file globing characters) - the big-word is replaced  with
                     the  resulting  words.   If  the  current big-word is the
                     first on the line (or follows one of the following  char-
                     acters:  ;,  |, &, (, )) and does not contain a slash (/)
                     then command  expansion  is  done,  otherwise  file  name
                     expansion is done.  Command expansion will match the big-
                     word against all aliases, functions and built-in commands
                     as  well  as  any executable files found by searching the
                     directories in the PATH parameter.  File  name  expansion
                     matches  the  big-word  against  the files in the current
                     directory.  After expansion, the cursor  is  placed  just
                     past the last word and the editor is in insert mode.

              n\, n^F, n<tab> and n<esc>
                     command/file  name  completion:  replace the current big-
                     word with the longest unique match  obtained  after  per-
                     forming  command/file name expansion.  <tab> is only rec-
                     ognized if the vi-tabcomplete option is set, while  <esc>
                     is  only  recognized  if the vi-esccomplete option is set
                     (see set -o).  If n is specified, the nth  possible  com-
                     pletion is selected (as reported by the command/file name
                     enumeration command).

              = and ^E
                     command/file name enumeration: list all the  commands  or
                     files that match the current big-word.

              ^V     display  the  version  of  pdksh;  it  is displayed until
                     another key is pressed (this key is ignored).

              @c     macro expansion: execute the commands found in the  alias
                     _c.

       Intra-line movement commands

              nh and n^H
                     move left n characters.

              nl and n<space>
                     move right n characters.

              0      move to column 0.

              ^      move to the first non white-space character.

              n|     move to column n.

              $      move to the last character.

              nb     move back n words.

              nB     move back n big-words.

              ne     move forward to the end the word, n times.

              nE     move forward to the end the big-word, n times.

              nw     move forward n words.

              nW     move forward n big-words.

              %      find  match:  the  editor  looks  forward for the nearest
                     parenthesis, bracket or brace and then moves the  to  the
                     matching parenthesis, bracket or brace.

              nfc    move forward to the nth occurrence of the character c.

              nFc    move backward to the nth occurrence of the character c.

              ntc    move  forward  to  just  before the nth occurrence of the
                     character c.

              nTc    move backward to just before the nth  occurrence  of  the
                     character c.

              n;     repeats the last f, F, t or T command.

              n,     repeats  the  last f, F, t or T command, but moves in the
                     opposite direction.

       Inter-line movement commands

              nj and n+ and n^N
                     move to the nth next line in the history.

              nk and n- and n^P
                     move to the nth previous line in the history.

              nG     move to line n in the history; if n is not specified, the
                     number first remembered line is used.

              ng     like G, except if n is not specified, it goes to the most
                     recent remembered line.

              n/string
                     search backward through the history for the nth line con-
                     taining string; if string starts with ^, the remainder of
                     the string must appear at the start of the  history  line
                     for it to match.

              n?string
                     same  as  /,  except it searches forward through the his-
                     tory.

              nn     search for the nth occurrence of the last search  string;
                     the  direction  of  the  search  is  the same as the last
                     search.

              nN     search for the nth occurrence of the last search  string;
                     the  direction  of the search is the opposite of the last
                     search.

       Edit commands

              na     append text n times: goes into insert mode just after the
                     current  position.  The append is only replicated if com-
                     mand mode is re-entered (i.e., <esc> is used).

              nA     same as a, except it appends at the end of the line.

              ni     insert text n times: goes into insert mode at the current
                     position.   The  insertion  is only replicated if command
                     mode is re-entered (i.e., <esc> is used).

              nI     same as i, except the insertion is done just  before  the
                     first non-blank character.

              ns     substitute  the next n characters (i.e., delete the char-
                     acters and go into insert mode).

              S      substitute whole line: all characters from the first non-
                     blank character to the end of line are deleted and insert
                     mode is entered.

              ncmove-cmd
                     change from the current position to the position  result-
                     ing  from  n move-cmds (i.e., delete the indicated region
                     and go into insert mode); if  move-cmd  is  c,  the  line
                     starting from the first non-blank character is changed.

              C      change  from  the current position to the end of the line
                     (i.e., delete to the end of the line and go  into  insert
                     mode).

              nx     delete the next n characters.

              nX     delete the previous n characters.

              D      delete to the end of the line.

              ndmove-cmd
                     delete  from the current position to the position result-
                     ing from n move-cmds; move-cmd is a movement command (see
                     above) or d, in which case the current line is deleted.

              nrc    replace the next n characters with the character c.

              nR     replace: enter insert mode but overwrite existing charac-
                     ters instead of  inserting  before  existing  characters.
                     The replacement is repeated n times.

              n~     change the case of the next n characters.

              nymove-cmd
                     yank  from the current position to the position resulting
                     from n move-cmds into the yank buffer; if move-cmd is  y,
                     the whole line is yanked.

              Y      yank from the current position to the end of the line.

              np     paste the contents of the yank buffer just after the cur-
                     rent position, n times.

              nP     same as p, except the buffer is  pasted  at  the  current
                     position.

       Miscellaneous vi commands

              ^J and ^M
                     the  current  line  is  read,  parsed and executed by the
                     shell.

              ^L and ^R
                     redraw the current line.

              n.     redo the last edit command n times.

              u      undo the last edit command.

              U      undo all changes that have been made to the current line.

              intr and quit
                     the interrupt and quit terminal characters cause the cur-
                     rent line to be deleted and a new prompt to be printed.

FILES
       ~/.kshrc
       ~/.profile
       /etc/profile
       /etc/suid_profile

BUGS
       Any bugs in  pdksh  should  be  reported  to  pdksh@cs.mun.ca.   Please
       include the version of pdksh (echo $KSH_VERSION shows it), the machine,
       operating system and compiler you are using and a description of how to
       repeat  the  bug  (a  small  shell  script that demonstrates the bug is
       best).  The following, if relevant (if you are not sure, include them),
       can also helpful: options you are using (both options.h options and set
       -o options) and a copy of your config.h (the file generated by the con-
       figure   script).    New   versions  of  pdksh  can  be  obtained  from
       ftp://ftp.cs.mun.ca/pub/pdksh/.

       BTW, the most frequently reported bug is
               echo hi | read a; echo $a   # Does not print hi
       I'm aware of this and there is no need to report it.

VERSION
       This page documents version
                            @(#)PD KSH v5.2.14 99/07/13.2
       of the public domain korn shell.

AUTHORS
       This shell is based on the public domain 7th edition Bourne shell clone
       by  Charles  Forsyth  and  parts of the BRL shell by Doug A. Gwyn, Doug
       Kingston, Ron Natalie, Arnold Robbins, Lou  Salkind  and  others.   The
       first  release  of  pdksh  was created by Eric Gisin, and it was subse-
       quently maintained by John R.  MacMillan  (chance!john@sq.sq.com),  and
       Simon  J.  Gerraty  (sjg@zen.void.oz.au).   The  current  maintainer is
       Michael Rendell (michael@cs.mun.ca).   The  CONTRIBUTORS  file  in  the
       source  distribution  contains a more complete list of people and their
       part in the shell's development.

SEE ALSO
       awk(1), sh(1), csh(1), ed(1), getconf(1), getopt(1),  sed(1),  stty(1),
       vi(1),  dup(2),  execve(2),  getgid(2),  getuid(2),  open(2),  pipe(2),
       wait(2), getopt(3), rand(3), signal(3), system(3), environ(7)

       The KornShell Command and Programming Language, Morris Bolsky and David
       Korn, 1989, ISBN 0-13-516972-0.

       UNIX Shell Programming, Stephen G. Kochan, Patrick H. Wood, Hayden.

       IEEE  Standard  for  information Technology - Portable Operating System
       Interface (POSIX) - Part 2: Shell and Utilities, IEEE Inc,  1993,  ISBN
       1-55937-255-9.



                                August 19, 1996                         KSH(1)

You can also request any man page by name and (optionally) by section:

Command: 
Section: 
Architecture: 
Collection: 
 

Use the DEFAULT collection to view manual pages for third-party software.


©1994 Man-cgi 1.15, Panagiotis Christias <christia@softlab.ntua.gr>
©1996-2014 Modified for NetBSD by Kimmo Suominen