MAKE(1)                 NetBSD General Commands Manual                 MAKE(1)

NAME
     make -- maintain program dependencies

SYNOPSIS
     make [-BeikNnqrstWwX] [-C directory] [-D variable] [-d flags]
          [-f makefile] [-I directory] [-J private] [-j max_jobs]
          [-m directory] [-T file] [-V variable] [variable=value] [target ...]

DESCRIPTION
     make is a program designed to simplify the maintenance of other programs.
     Its input is a list of specifications as to the files upon which programs
     and other files depend.  If no -f makefile makefile option is given, make
     will try to open `makefile' then `Makefile' in order to find the specifi-
     cations.  If the file `.depend' exists, it is read (see mkdep(1)).

     This manual page is intended as a reference document only.  For a more
     thorough description of make and makefiles, please refer to PMake - A
     Tutorial.

     make will prepend the contents of the MAKEFLAGS environment variable to
     the command line arguments before parsing them.

     The options are as follows:

     -B      Try to be backwards compatible by executing a single shell per
             command and by executing the commands to make the sources of a
             dependency line in sequence.

     -C directory
             Change to directory before reading the makefiles or doing any-
             thing else.  If multiple -C options are specified, each is inter-
             preted relative to the previous one: -C / -C etc is equivalent to
             -C /etc.

     -D variable
             Define variable to be 1, in the global context.

     -d [-]flags
             Turn on debugging, and specify which portions of make are to
             print debugging information.  Unless the flags are preceded by
             `-' they are added to the MAKEFLAGS environment variable and will
             be processed by any child make processes.  By default, debugging
             information is printed to standard error, but this can be changed
             using the F debugging flag.  The debugging output is always
             unbuffered; in addition, if debugging is enabled but debugging
             output is not directed to standard output, then the standard out-
             put is line buffered.  Flags is one or more of the following:

             A       Print all possible debugging information; equivalent to
                     specifying all of the debugging flags.

             a       Print debugging information about archive searching and
                     caching.

             C       Print debugging information about current working direc-
                     tory.

             c       Print debugging information about conditional evaluation.

             d       Print debugging information about directory searching and
                     caching.

             e       Print debugging information about failed commands and
                     targets.

             F[+]filename
                     Specify where debugging output is written.  This must be
                     the last flag, because it consumes the remainder of the
                     argument.  If the character immediately after the `F'
                     flag is `+', then the file will be opened in append mode;
                     otherwise the file will be overwritten.  If the file name
                     is `stdout' or `stderr' then debugging output will be
                     written to the standard output or standard error output
                     file descriptors respectively (and the `+' option has no
                     effect).  Otherwise, the output will be written to the
                     named file.  If the file name ends `.%d' then the `%d' is
                     replaced by the pid.

             f       Print debugging information about loop evaluation.

             g1      Print the input graph before making anything.

             g2      Print the input graph after making everything, or before
                     exiting on error.

             g3      Print the input graph before exiting on error.

             j       Print debugging information about running multiple
                     shells.

             l       Print commands in Makefiles regardless of whether or not
                     they are prefixed by `@' or other "quiet" flags.  Also
                     known as "loud" behavior.

             M       Print debugging information about "meta" mode decisions
                     about targets.

             m       Print debugging information about making targets, includ-
                     ing modification dates.

             n       Don't delete the temporary command scripts created when
                     running commands.  These temporary scripts are created in
                     the directory referred to by the TMPDIR environment vari-
                     able, or in /tmp if TMPDIR is unset or set to the empty
                     string.  The temporary scripts are created by mkstemp(3),
                     and have names of the form makeXXXXXX.  NOTE: This can
                     create many files in TMPDIR or /tmp, so use with care.

             p       Print debugging information about makefile parsing.

             s       Print debugging information about suffix-transformation
                     rules.

             t       Print debugging information about target list mainte-
                     nance.

             V       Force the -V option to print raw values of variables.

             v       Print debugging information about variable assignment.

             x       Run shell commands with -x so the actual commands are
                     printed as they are executed.

     -e      Specify that environment variables override macro assignments
             within makefiles.

     -f makefile
             Specify a makefile to read instead of the default `makefile'.  If
             makefile is `-', standard input is read.  Multiple makefiles may
             be specified, and are read in the order specified.

     -I directory
             Specify a directory in which to search for makefiles and included
             makefiles.  The system makefile directory (or directories, see
             the -m option) is automatically included as part of this list.

     -i      Ignore non-zero exit of shell commands in the makefile.  Equiva-
             lent to specifying `-' before each command line in the makefile.

     -J private
             This option should not be specified by the user.

             When the j option is in use in a recursive build, this option is
             passed by a make to child makes to allow all the make processes
             in the build to cooperate to avoid overloading the system.

     -j max_jobs
             Specify the maximum number of jobs that make may have running at
             any one time.  The value is saved in .MAKE.JOBS.  Turns compati-
             bility mode off, unless the B flag is also specified.  When com-
             patibility mode is off, all commands associated with a target are
             executed in a single shell invocation as opposed to the tradi-
             tional one shell invocation per line.  This can break traditional
             scripts which change directories on each command invocation and
             then expect to start with a fresh environment on the next line.
             It is more efficient to correct the scripts rather than turn
             backwards compatibility on.

     -k      Continue processing after errors are encountered, but only on
             those targets that do not depend on the target whose creation
             caused the error.

     -m directory
             Specify a directory in which to search for sys.mk and makefiles
             included via the <file>-style include statement.  The -m option
             can be used multiple times to form a search path.  This path will
             override the default system include path: /usr/share/mk.  Fur-
             thermore the system include path will be appended to the search
             path used for "file"-style include statements (see the -I
             option).

             If a file or directory name in the -m argument (or the
             MAKESYSPATH environment variable) starts with the string ".../"
             then make will search for the specified file or directory named
             in the remaining part of the argument string.  The search starts
             with the current directory of the Makefile and then works upward
             towards the root of the filesystem.  If the search is successful,
             then the resulting directory replaces the ".../" specification in
             the -m argument.  If used, this feature allows make to easily
             search in the current source tree for customized sys.mk files
             (e.g., by using ".../mk/sys.mk" as an argument).

     -n      Display the commands that would have been executed, but do not
             actually execute them unless the target depends on the .MAKE spe-
             cial source (see below).

     -N      Display the commands which would have been executed, but do not
             actually execute any of them; useful for debugging top-level
             makefiles without descending into subdirectories.

     -q      Do not execute any commands, but exit 0 if the specified targets
             are up-to-date and 1, otherwise.

     -r      Do not use the built-in rules specified in the system makefile.

     -s      Do not echo any commands as they are executed.  Equivalent to
             specifying `@' before each command line in the makefile.

     -T tracefile
             When used with the -j flag, append a trace record to tracefile
             for each job started and completed.

     -t      Rather than re-building a target as specified in the makefile,
             create it or update its modification time to make it appear up-
             to-date.

     -V variable
             Print make's idea of the value of variable, in the global con-
             text.  Do not build any targets.  Multiple instances of this
             option may be specified; the variables will be printed one per
             line, with a blank line for each null or undefined variable.  If
             variable contains a `$' then the value will be expanded before
             printing.

     -W      Treat any warnings during makefile parsing as errors.

     -w      Print entering and leaving directory messages, pre and post pro-
             cessing.

     -X      Don't export variables passed on the command line to the environ-
             ment individually.  Variables passed on the command line are
             still exported via the MAKEFLAGS environment variable.  This
             option may be useful on systems which have a small limit on the
             size of command arguments.

     variable=value
             Set the value of the variable variable to value.  Normally, all
             values passed on the command line are also exported to sub-makes
             in the environment.  The -X flag disables this behavior.  Vari-
             able assignments should follow options for POSIX compatibility
             but no ordering is enforced.

     There are seven different types of lines in a makefile: file dependency
     specifications, shell commands, variable assignments, include statements,
     conditional directives, for loops, and comments.

     In general, lines may be continued from one line to the next by ending
     them with a backslash (`\').  For any line that is not a shell command
     line (i.e. it does not begin with a tab), the backslash, the following
     newline character, and initial whitespace on the following line are com-
     pressed into a single space.  On command lines the backslash and the new-
     line are left intact and if the following line begins with tab(s), the
     first one is removed.

FILE DEPENDENCY SPECIFICATIONS
     Dependency lines consist of one or more targets, an operator, zero or
     more sources, and an optional semicolon followed by a command.  This cre-
     ates a relationship where the targets ``depend'' on the sources and are
     usually created from them.

           target [target...]: [source...] [;command]

     The exact relationship between the target and the source is determined by
     the operator, presented by a colon in the example, that separates them.
     A target may only appear on the left hand side of one type of operator in
     a single makefile.  The three operators are as follows:

     :     A target is considered out-of-date if its modification time is less
           than those of any of its sources.  Sources for a target accumulate
           over dependency lines when this operator is used.  The target is
           removed if make is interrupted.  This is the only operator avail-
           able in POSIX compatible makefiles.

     !     Targets are always re-created, but not until all sources have been
           examined and re-created as necessary.  Sources for a target accumu-
           late over dependency lines when this operator is used.  The target
           is removed if make is interrupted.

     ::    If no sources are specified, the target is always re-created.  Oth-
           erwise, a target is considered out-of-date if any of its sources
           has been modified more recently than the target.  Sources for a
           target do not accumulate over dependency lines when this operator
           is used, only the depencies in the first rule encountered are used.
           The commands from the rules do accumulate and are executed in the
           order the rules were defined if the target needs to be updated.
           The target will not be removed if make is interrupted.

     The optional semicolon separated command in the dependency line is
     strongly discouraged except to specify an empty rule to nullify an exist-
     ing suffix transformation rule (see .SUFFIXES).  More information on com-
     mands is in the section SHELL COMMANDS.

     Targets and sources may contain the shell wildcard values `?', `*', `[]',
     and `{}'.  The values `?', `*', and `[]' may only be used as part of the
     final component of the target or source, and must be used to describe
     existing files.  The value `{}' need not necessarily be used to describe
     existing files.  Expansion is in directory order, not alphabetically as
     done in the shell.

   Suffix transformation rules
     Suffix transformation rules allow make to infer the commands used to
     bring targets up to date based on their suffixes.  These are also known
     as inference rules or just suffix rules.  A suffix transformation rule is
     a rule whose dependency line has either of these forms:
           .s1.s2: [source...]
           .s1: [source...]
     Additionally, both .s1 and .s2 need to be defined as dependencies on the
     special target .SUFFIXES.

     A suffix transformation rule tells make that any file named file.s2 (the
     first form) or file (the second form) can be made with the provided rules
     from a file named file.s1.  Suffix transformation rules are only tried
     when there is no explicit rule to make a target.  Single suffix rules
     (ther second form) are only tried if the target has no known suffix.
     Suffixes are tried in the order they have been specified to the .SUFFIXES
     special target.  An explicit dependency line with no commands can be used
     to add more dependencies, while still allowing for the use of the
     inferred commands.

     In POSIX compatible makefiles there are no sources listed in a suffix
     transformation rule definition and only a single transformation step is
     tried.  This implementation allows dependencies to be listed and handles
     them as additional dependencies on any file that gets created with the
     suffix transformation.  This can be combined with dynamic sources.
     Transformations can also be chained: if file.s1 could be made from
     file.s2 but it does not exist, make will try the suffix transformation
     rules which could make it from any file.s3 and so forth.  The shortest
     path from an existing file or an explicit rule will be chosen.

     Usable commands for these rules cannot be written without knowing what
     the actual sources and targets are.  This information is provided with
     the local variables listed in the section ``Variable classes''.

   Archive member targets
     A target or a source of the form archive(member) refers to file member in
     an ar library archive named archive.  The modification time stored for
     the member in the archive is used in up-to-dateness checks.  In POSIX
     compatible makefiles the member file must be an object file and have the
     suffix .o.

     Library members can also be inferred.  The POSIX compatible way is to
     define a suffix transformation rule with the name .s1.a, as .a is the
     traditional suffix of such archives.  This rule is used to update
     member.o from the file member.s1 in any archive file, regardless of any
     suffix the archive file may or may not have.

     As an extension, if the POSIX compatible behavior does not yield com-
     mands, make looks if it could make the member if it were a regular file.
     If it can, then it tries to find a transformation rule from that file to
     the suffix of the archive for adding the file in to the archive.

SHELL COMMANDS
     Each target may have associated with it a series of shell commands, which
     immediately follow the dependency line.  These commands are normally used
     to create a file corresponding to the target name.  The first command
     line (or only line, if there is only one) may be on the same line with
     the dependency information, separated by a semicolon.  Every command line
     in this script following the dependency line must be preceded by a tab.
     Placing commands on the dependency line is not a good practice.

     A target name may appear on the left hand side of the dependency operator
     in any number of dependency lines.  Only one of these dependency specifi-
     cations may be followed by a creation script, unless the `::' operator is
     used.  If more than one rule with commands is encountered, the last one
     is used.  Overriding rules has its use cases, but sometimes it can happen
     by accident.  A notice of each overridden rule is included in the parsing
     debugging category.

     If the first characters of the command line are any combination of `@',
     `+', or `-', the command is treated specially.  A `@' causes the command
     not to be echoed before it is executed.  A `+' causes the command to be
     executed even when -n is given.  This is similar to the effect of the
     .MAKE special source, except that the effect can be limited to a single
     line of a script.  A `-' causes any non-zero exit status of the command
     line to be ignored.

     When make is run in jobs mode with -j max_jobs, the entire script for the
     target is fed to a single instance of the shell.

     In compatibility (non-jobs) mode, each command is run in a separate
     process.  If the command contains any shell meta characters
     (`#=|^(){};&<>*?[]:$`\\n') it will be passed to the shell, otherwise make
     will attempt direct execution.

     Since make will chdir(2) to `.OBJDIR' before executing any targets, each
     child process starts with that as its current working directory.

     Makefiles should be written so that the mode of make operation does not
     change their behavior.  For example, any command which needs to use
     ``cd'' or ``chdir'' without side-effects should be put in parenthesis so
     they are executed in a subshell:


           avoid-chdir-side-effects:
                   @echo Building $@ in `pwd`
                   @(cd ${.CURDIR} && ${MAKE} $@)
                   @echo Back in `pwd`

           ensure-one-shell-regardless-of-mode:
                   @echo Building $@ in `pwd`; \
                   (cd ${.CURDIR} && ${MAKE} $@); \
                   echo Back in `pwd`

     The backslash and the following newline are retained in the input to the
     shell, but if the next line starts with tab(s), the first one of those is
     removed.  This allows you to align the commands in the rule without
     introducing unwanted whitespace into the command line itself.  What hap-
     pens to the backslash-newline pair is up to the shell.  The standard
     shell, sh(1), removes them both elsewhere than in single quotes, effec-
     tively catenating the two lines.  The following examples demonstrate
     escaped newlines in command lines.

           echo-foobar:      |  syntax-error:
           |                 |
               bar"          |
                             |
                             |      done

     The first one is an unnecessarily contrived way of doing

     echo "foobar"
     The second one demonstrates why the semicolon is required in many places
     where in a similar looking regular shell script it wouldn't be.  After
     the shell has removed the backslash newline pairs, the result would be
     the syntactically incorrect command

     for i in a bdo  echo $idone

VARIABLE ASSIGNMENTS
     Variables in make are much like variables in the shell, and, by tradi-
     tion, consist of all upper-case letters.

   Variable assignment modifiers
     The five operators that can be used to assign values to variables are as
     follows:

     =       Assign the value to the variable.  Any previous value is overrid-
             den.

     +=      Append the value to the current value of the variable.

     ?=      Assign the value to the variable if it is not already defined.

     :=      Assign with expansion, i.e. expand the value before assigning it
             to the variable.  Normally, expansion is not done until the vari-
             able is referenced.  NOTE: References to undefined variables are
             not expanded.  This can cause problems when variable modifiers
             are used.

     !=      Expand the value and pass it to the shell for execution and
             assign the result to the variable.  Any newlines in the result
             are replaced with spaces.

     Any white-space before the assigned value is removed; if the value is
     being appended, a single space is inserted between the previous contents
     of the variable and the appended value.

     Variables are expanded by surrounding the variable name with either curly
     braces (`{}') or parentheses (`()') and preceding it with a dollar sign
     (`$').  If the variable name contains only a single letter, the surround-
     ing braces or parentheses are not required.  This shorter form is not
     recommended.

     If the variable name contains a dollar, then the name itself is expanded
     first.  This allows almost arbitrary variable names, however names con-
     taining dollar, braces, parenthesis, or whitespace are really best
     avoided!

     If the result of expanding a variable contains a dollar sign (`$') the
     string is expanded again.

     Variable substitution occurs at three distinct times, depending on where
     the variable is being used.

     1.   Variables in dependency lines are expanded as the line is read.

     2.   Variables in shell commands are expanded when the shell command is
          executed.

     3.   ``.for'' loop index variables are expanded on each loop iteration.
          Note that other variables are not expanded inside loops so the fol-
          lowing example code:


                .for i in 1 2 3
                a+=     ${i}
                j=      ${i}
                b+=     ${j}
                .endfor

                all:
                        @echo ${a}
                        @echo ${b}

          will print:

                1 2 3
                3 3 3

          Because while ${a} contains ``1 2 3'' after the loop is executed,
          ${b} contains ``${j} ${j} ${j}'' which expands to ``3 3 3'' since
          after the loop completes ${j} contains ``3''.

   Variable classes
     The four different classes of variables (in order of increasing prece-
     dence) are:

     Environment variables
             Variables defined as part of make's environment.

     Global variables
             Variables defined in the makefile or in included makefiles.

     Command line variables
             Variables defined as part of the command line.

     Local variables
             There are seven variables that are defined specific to a certain
             target.  Five of these are defined in POSIX but only in their
             short form.  The variables are as follows:

             .ALLSRC   The list of all sources for this target; also known as
                       `>'.  This variable is a non-POSIX extension.

             .ARCHIVE  The name of the archive file; also known as `!'.  This
                       variable is a non-POSIX extension.

             .IMPSRC   In suffix-transformation rules it is the name of the
                       source from which the target is to be transformed (the
                       ``implied'' source).  In explicit rules it is the name
                       of the first dependency from the dependency line of the
                       explicit rule or in the absence of such a prerequisite,
                       the first dependency otherwise encountered.  If the
                       source was actually found via path search, it is the
                       resulting path name.  Also known as `<'.

             .MEMBER   The name of the archive member; also known as `%'.  It
                       is only defined for archive(member) targets or in
                       inference rules used to make such targets.

             .OODATE   The list of sources for this target that were deemed
                       out-of-date; also known as `?'.

             .PREFIX   The file prefix of the target, containing only the file
                       portion, no suffix or preceding directory components;
                       also known as `*'.  For an archive member rule it is
                       the prefix of the member.

                       POSIX only requires this variable to be availabe for
                       suffix transformation rules, but this implementation
                       makes it available for all targets.  If the target does
                       not have a known suffix (see .SUFFIXES), it is equiva-
                       lent to `.TARGET'.

             .TARGET   The name of the target; also known as `@'.  In an
                       explicit rule for archive(member.o) or in a POSIX style
                       .s1.a suffix transformation rule this is equal to
                       `.ARCHIVE'.

             To increase readability, the shorter forms (`@', `!', `%', `?',
             `<', `>', and `*') should only be used when compatibility with
             POSIX or other implementations is desired.  For compatibility
             with POSIX, all of the short forms may also be written with an
             appended uppercase `D' or `F', e.g. `@D' or `*F'.  These modified
             versions replace each word in the expansion with their directory
             part (`D') or filename part (`F'), and are exactly equivalent to
             the :H and :T variable modifiers, respectively.

             Four of the local variables may be used in sources on dependency
             lines because they expand to the proper value for each target on
             the line.  These variables are `.TARGET', `.PREFIX', `.ARCHIVE',
             and `.MEMBER'.  Dependencies based on these variables are called
             dynamic sources and they are not POSIX compatible.

   Additional built-in variables
     In addition, make sets or knows about the following variables:

     $               A single dollar sign `$', i.e.  `$$' expands to a single
                     dollar sign.

     .ALLTARGETS     The list of all targets encountered in the Makefile.  If
                     evaluated during Makefile parsing, lists only those tar-
                     gets encountered thus far.

     .CURDIR         A path to the directory where make was executed.  Refer
                     to the description of `PWD' for more details.

     .INCLUDEDFROMDIR
                     The directory of the file this Makefile was included
                     from.

     .INCLUDEDFROMFILE
                     The filename of the file this Makefile was included from.

     MAKE            The name that make was executed with (argv[0]).  For com-
                     patibility make also sets .MAKE with the same value.  The
                     preferred variable to use is the environment variable
                     MAKE because it is more compatible with other versions of
                     make and cannot be confused with the special target with
                     the same name.

     .MAKE.DEPENDFILE
                     Names the makefile (default `.depend') from which gener-
                     ated dependencies are read.

     .MAKE.EXPAND_VARIABLES
                     A boolean that controls the default behavior of the -V
                     option.

     .MAKE.EXPORTED  The list of variables exported by make.

     .MAKE.JOBS      The argument to the -j option.

     .MAKE.JOB.PREFIX
                     If make is run with j then output for each target is pre-
                     fixed with a token `--- target ---' the first part of
                     which can be controlled via .MAKE.JOB.PREFIX.  If
                     .MAKE.JOB.PREFIX is empty, no token is printed.
                     For example:
                     .MAKE.JOB.PREFIX=${.newline}---${.MAKE:T}[${.MAKE.PID}]
                     would produce tokens like `---make[1234] target ---' mak-
                     ing it easier to track the degree of parallelism being
                     achieved.

     MAKEFLAGS       The environment variable `MAKEFLAGS' may contain anything
                     that may be specified on make's command line.  Anything
                     specified on make's command line is appended to the
                     `MAKEFLAGS' variable which is then entered into the envi-
                     ronment for all programs which make executes.

     .MAKE.LEVEL     The recursion depth of make.  The initial instance of
                     make will be 0, and an incremented value is put into the
                     environment to be seen by the next generation.  This
                     allows tests like: .if ${.MAKE.LEVEL} == 0 to protect
                     things which should only be evaluated in the initial
                     instance of make.

     .MAKE.MAKEFILE_PREFERENCE
                     The ordered list of makefile names (default `makefile',
                     `Makefile') that make will look for.

     .MAKE.MAKEFILES
                     The list of makefiles read by make, which is useful for
                     tracking dependencies.  Each makefile is recorded only
                     once, regardless of the number of times read.

     .MAKE.MODE      Processed after reading all makefiles.  Can affect the
                     mode that make runs in.  It can contain a number of key-
                     words:

                     compat      Like -B, puts make into "compat" mode.

                     meta        Puts make into "meta" mode, where meta files
                                 are created for each target to capture the
                                 command run, the output generated and if
                                 filemon(4) is available, the system calls
                                 which are of interest to make.  The captured
                                 output can be very useful when diagnosing
                                 errors.

                     curdirOk= bf Normally make will not create .meta files in
                                 `.CURDIR'.  This can be overridden by setting
                                 bf to a value which represents True.

                     env         For debugging, it can be useful to inlcude
                                 the environment in the .meta file.

                     verbose     If in "meta" mode, print a clue about the
                                 target being built.  This is useful if the
                                 build is otherwise running silently.  The
                                 message printed the value of:
                                 .MAKE.META.PREFIX.

                     ignore-cmd  Some makefiles have commands which are simply
                                 not stable.  This keyword causes them to be
                                 ignored for determining whether a target is
                                 out of date in "meta" mode.  See also
                                 .NOMETA_CMP.

                     silent= bf  If bf is True, when a .meta file is created,
                                 mark the target .SILENT.

     .MAKE.META.BAILIWICK
                     In "meta" mode, provides a list of prefixes which match
                     the directories controlled by make.  If a file that was
                     generated outside of .OBJDIR but within said bailiwick is
                     missing, the current target is considered out-of-date.

     .MAKE.META.CREATED
                     In "meta" mode, this variable contains a list of all the
                     meta files updated.  If not empty, it can be used to
                     trigger processing of .MAKE.META.FILES.

     .MAKE.META.FILES
                     In "meta" mode, this variable contains a list of all the
                     meta files used (updated or not).  This list can be used
                     to process the meta files to extract dependency informa-
                     tion.

     .MAKE.META.IGNORE_PATHS
                     Provides a list of path prefixes that should be ignored;
                     because the contents are expected to change over time.
                     The default list includes: `/dev /etc /proc /tmp /var/run
                     /var/tmp'

     .MAKE.META.PREFIX
                     Defines the message printed for each meta file updated in
                     "meta verbose" mode.  The default value is:
                           Building ${.TARGET:H:tA}/${.TARGET:T}

     .MAKEOVERRIDES  This variable is used to record the names of variables
                     assigned to on the command line, so that they may be
                     exported as part of `MAKEFLAGS'.  This behaviour can be
                     disabled by assigning an empty value to `.MAKEOVERRIDES'
                     within a makefile.  Extra variables can be exported from
                     a makefile by appending their names to `.MAKEOVERRIDES'.
                     `MAKEFLAGS' is re-exported whenever `.MAKEOVERRIDES' is
                     modified.

     .MAKE.PATH_FILEMON
                     If make was built with filemon(4) support, this is set to
                     the path of the device node.  This allows makefiles to
                     test for this support.

     .MAKE.PID       The process-id of make.

     .MAKE.PPID      The parent process-id of make.

     MAKE_PRINT_VAR_ON_ERROR
                     When make stops due to an error, it prints its name and
                     the value of `.CURDIR' as well as the value of any vari-
                     ables named in `MAKE_PRINT_VAR_ON_ERROR'.

     .newline        This variable is simply assigned a newline character as
                     its value.  This allows expansions using the :@ modifier
                     to put a newline between iterations of the loop rather
                     than a space.  For example, the printing of
                     `MAKE_PRINT_VAR_ON_ERROR' could be done as
                     ${MAKE_PRINT_VAR_ON_ERROR:@v@$v='${$v}'${.newline}@}.

     .OBJDIR         A path to the directory where the targets are built.  Its
                     value is determined by trying to chdir(2) to the follow-
                     ing directories in order and using the first match:

                     1.   ${MAKEOBJDIRPREFIX}${.CURDIR}

                          (Only if `MAKEOBJDIRPREFIX' is set in the environ-
                          ment or on the command line.)

                     2.   ${MAKEOBJDIR}

                          (Only if `MAKEOBJDIR' is set in the environment or
                          on the command line.)

                     3.   ${.CURDIR}/obj.${MACHINE}

                     4.   ${.CURDIR}/obj

                     5.   /usr/obj/${.CURDIR}

                     6.   ${.CURDIR}

                     Variable expansion is performed on the value before it's
                     used, so expressions such as
                           ${.CURDIR:S,^/usr/src,/var/obj,}
                     may be used.  This is especially useful with
                     `MAKEOBJDIR'.

                     `.OBJDIR' may be modified in the makefile as a global
                     variable.  In all cases, make will chdir(2) to `.OBJDIR'
                     and set `PWD' to that directory before executing any tar-
                     gets.

     .PARSEDIR       A path to the directory of the current `Makefile' being
                     parsed.

     .PARSEFILE      The basename of the current `Makefile' being parsed.
                     This variable and `.PARSEDIR' are both set only while the
                     `Makefiles' are being parsed.  If you want to retain
                     their current values, assign them to a variable using
                     assignment with expansion: (`:=').

     .PATH           A variable that represents the list of directories that
                     make will search for files.  The search list should be
                     updated using the target `.PATH' rather than the vari-
                     able.

     PWD             Alternate path to the current directory.  make normally
                     sets `.CURDIR' to the canonical path given by getcwd(3).
                     However, if the environment variable `PWD' is set and
                     gives a path to the current directory, then make sets
                     `.CURDIR' to the value of `PWD' instead.  This behaviour
                     is disabled if `MAKEOBJDIRPREFIX' is set or `MAKEOBJDIR'
                     contains a variable transform.  `PWD' is set to the value
                     of `.OBJDIR' for all programs which make executes.

     .TARGETS        The list of targets explicitly specified on the command
                     line, if any.

     VPATH           Colon-separated (``:'') lists of directories that make
                     will search for files.  The variable is supported for
                     compatibility with old make programs only, use `.PATH'
                     instead.

   Variable modifiers
     Variable expansion may be modified to select or modify each word of the
     variable (where a ``word'' is white-space delimited sequence of charac-
     ters).  The general format of a variable expansion is as follows:

           ${variable[:modifier[:...]]}

     Each modifier begins with a colon, which may be escaped with a backslash
     (`\').

     A set of modifiers can be specified via a variable, as follows:

           modifier_variable=modifier[:...]
           ${variable:${modifier_variable}[:...]}

     In this case the first modifier in the modifier_variable does not start
     with a colon, since that must appear in the referencing variable.  If any
     of the modifiers in the modifier_variable contain a dollar sign (`$'),
     these must be doubled to avoid early expansion.

     Variable modifiers are not POSIX compatible except for
     `:old_string=new_string', `:H' and `:T'.  Even these have notable
     caveats, see their individual descriptions.

     The supported modifiers are:

     :E   Replaces each word in the variable with its suffix.

     :H   Replaces each word in the variable with everything but the last com-
          ponent (`head only').  In POSIX compatible makefiles this modifica-
          tion is only available for local variables and with different syn-
          tax.  It is achieved by writing the variable with an appended `D',
          e.g. `@D'.

     :Mpattern
          Select only those words that match pattern.  The standard shell
          wildcard characters (`*', `?', and `[]') may be used.  The wildcard
          characters may be escaped with a backslash (`\').  As a consequence
          of the way values are split into words, matched, and then joined, a
          construct like
                ${VAR:M*}
          will normalise the inter-word spacing, removing all leading and
          trailing space, and converting multiple consecutive spaces to single
          spaces.

     :Npattern
          This is identical to `:M', but selects all words which do not match
          pattern.

     :O   Order every word in variable alphabetically.  To sort words in
          reverse order use the `:O:[-1..1]' combination of modifiers.

     :Ox  Randomize words in variable.  The results will be different each
          time you are referring to the modified variable; use the assignment
          with expansion (`:=') to prevent such behaviour.  For example,

                LIST=                   uno due tre quattro
                RANDOM_LIST=            ${LIST:Ox}
                STATIC_RANDOM_LIST:=    ${LIST:Ox}

                all:
                        @echo "${RANDOM_LIST}"
                        @echo "${RANDOM_LIST}"
                        @echo "${STATIC_RANDOM_LIST}"
                        @echo "${STATIC_RANDOM_LIST}"
          may produce output similar to:

                quattro due tre uno
                tre due quattro uno
                due uno quattro tre
                due uno quattro tre

     :Q   Quotes every shell meta-character in the variable, so that it can be
          passed safely through recursive invocations of make.

     :R   Replaces each word in the variable with everything but its suffix.

     :gmtime
          The value is a format string for strftime(3), using the current
          gmtime(3).

     :hash
          Compute a 32bit hash of the value and encode it as hex digits.

     :localtime
          The value is a format string for strftime(3), using the current
          localtime(3).

     :tA  Attempt to convert variable to an absolute path using realpath(3),
          if that fails, the value is unchanged.

     :tl  Converts variable to lower-case letters.

     :tsc
          Words in the variable are normally separated by a space on expan-
          sion.  This modifier sets the separator to the character c.  If c is
          omitted, then no separator is used.  The common escapes (including
          octal numeric codes), work as expected.

     :tu  Converts variable to upper-case letters.

     :tW  Causes the value to be treated as a single word (possibly containing
          embedded white space).  See also `:[*]'.

     :tw  Causes the value to be treated as a sequence of words delimited by
          white space.  See also `:[@]'.

     :S/old_string/new_string/[1gW]
          Modify the first occurrence of old_string in the variable's value,
          replacing it with new_string.  If a `g' is appended to the last
          slash of the pattern, all occurrences in each word are replaced.  If
          a `1' is appended to the last slash of the pattern, only the first
          word is affected.  If a `W' is appended to the last slash of the
          pattern, then the value is treated as a single word (possibly con-
          taining embedded white space).  If old_string begins with a caret
          (`^'), old_string is anchored at the beginning of each word.  If
          old_string ends with a dollar sign (`$'), it is anchored at the end
          of each word.  Inside new_string, an ampersand (`&') is replaced by
          old_string (without any `^' or `$').  Any character may be used as a
          delimiter for the parts of the modifier string.  The anchoring,
          ampersand and delimiter characters may be escaped with a backslash
          (`\').

          Variable expansion occurs in the normal fashion inside both
          old_string and new_string with the single exception that a backslash
          is used to prevent the expansion of a dollar sign (`$'), not a pre-
          ceding dollar sign as is usual.

     :C/pattern/replacement/[1gW]
          The :C modifier is just like the :S modifier except that the old and
          new strings, instead of being simple strings, are an extended regu-
          lar expression (see regex(3)) string pattern and an ed(1)-style
          string replacement.  Normally, the first occurrence of the pattern
          pattern in each word of the value is substituted with replacement.
          The `1' modifier causes the substitution to apply to at most one
          word; the `g' modifier causes the substitution to apply to as many
          instances of the search pattern pattern as occur in the word or
          words it is found in; the `W' modifier causes the value to be
          treated as a single word (possibly containing embedded white space).
          Note that `1' and `g' are orthogonal; the former specifies whether
          multiple words are potentially affected, the latter whether multiple
          substitutions can potentially occur within each affected word.

          As for the :S modifier, the pattern and replacement are subjected to
          variable expansion before being parsed as regular expressions.

     :T   Replaces each word in the variable with its last component (`tail
          only').  In POSIX compatible makefiles this modification is only
          available for local variables and with different syntax.  It is
          achieved by writing the variable with an appended `F', e.g. `@F'.

     :u   Remove adjacent duplicate words (like uniq(1)).

     :?true_string:false_string
          If the variable name (not its value), when parsed as a .if condi-
          tional expression, evaluates to true, return as its value the
          true_string, otherwise return the false_string.  Since the variable
          name is used as the expression, :? must be the first modifier after
          the variable name itself - which will, of course, usually contain
          variable expansions.  A common error is trying to use expressions
          like
                ${NUMBERS:M42:?match:no}
          which actually tests defined(NUMBERS), to determine is any words
          match "42" you need to use something like:
                ${"${NUMBERS:M42}" != "":?match:no}.

     :old_string=new_string
          This is the AT&T System V UNIX style variable substitution, later
          standardized in POSIX.  It must be the last modifier specified.  If
          old_string or new_string do not contain the pattern matching charac-
          ter % then it is assumed that they are anchored at the end of each
          word, so only suffixes or entire words may be replaced.  Otherwise %
          is the substring of old_string to be replaced in new_string.  The
          special meaning of % is not POSIX compatible.

          Variable expansion occurs in the normal fashion inside both
          old_string and new_string with the single exception that a backslash
          is used to prevent the expansion of a dollar sign (`$'), not a pre-
          ceding dollar sign as is usual.

     :@temp@string@
          This is the loop expansion mechanism from the OSF Development Envi-
          ronment (ODE) make.  Unlike .for loops expansion occurs at the time
          of reference.  Assign temp to each word in the variable and evaluate
          string.  The ODE convention is that temp should start and end with a
          period.  For example.
                ${LINKS:@.LINK.@${LN} ${TARGET} ${.LINK.}@}

          However a single character variable is often more readable:
                ${MAKE_PRINT_VAR_ON_ERROR:@v@$v='${$v}'${.newline}@}

     :Unewval
          If the variable is undefined newval is the value.  If the variable
          is defined, the existing value is returned.  This is another ODE
          make feature.  It is handy for setting per-target CFLAGS for
          instance:
                ${_${.TARGET:T}_CFLAGS:U${DEF_CFLAGS}}
          If a value is only required if the variable is undefined, use:
                ${VAR:D:Unewval}

     :Dnewval
          If the variable is defined newval is the value.

     :L   The name of the variable is the value.

     :P   The path of the node which has the same name as the variable is the
          value.  If no such node exists or its path is null, then the name of
          the variable is used.  In order for this modifier to work, the name
          (node) must at least have appeared on the rhs of a dependency.

     :!cmd!
          The output of running cmd is the value.

     :sh  If the variable is non-empty it is run as a command and the output
          becomes the new value.

     ::=str
          The variable is assigned the value str after substitution.  This
          modifier and its variations are useful in obscure situations such as
          wanting to set a variable when shell commands are being parsed.
          These assignment modifiers always expand to nothing, so if appearing
          in a rule line by themselves should be preceded with something to
          keep make happy.

          The `::' helps avoid false matches with the AT&T System V UNIX style
          := modifier and since substitution always occurs the ::= form is
          vaguely appropriate.

     ::?=str
          As for ::= but only if the variable does not already have a value.

     ::+=str
          Append str to the variable.

     ::!=cmd
          Assign the output of cmd to the variable.

     :[range]
          Selects one or more words from the value, or performs other opera-
          tions related to the way in which the value is divided into words.

          Ordinarily, a value is treated as a sequence of words delimited by
          white space.  Some modifiers suppress this behaviour, causing a
          value to be treated as a single word (possibly containing embedded
          white space).  An empty value, or a value that consists entirely of
          white-space, is treated as a single word.  For the purposes of the
          `:[]' modifier, the words are indexed both forwards using positive
          integers (where index 1 represents the first word), and backwards
          using negative integers (where index -1 represents the last word).

          The range is subjected to variable expansion, and the expanded
          result is then interpreted as follows:

          index  Selects a single word from the value.

          start..end
                 Selects all words from start to end, inclusive.  For example,
                 `:[2..-1]' selects all words from the second word to the last
                 word.  If start is greater than end, then the words are out-
                 put in reverse order.  For example, `:[-1..1]' selects all
                 the words from last to first.

          *      Causes subsequent modifiers to treat the value as a single
                 word (possibly containing embedded white space).  Analogous
                 to the effect of "$*" in Bourne shell.

          0      Means the same as `:[*]'.

          @      Causes subsequent modifiers to treat the value as a sequence
                 of words delimited by white space.  Analogous to the effect
                 of "$@" in Bourne shell.

          #      Returns the number of words in the value.

INCLUDE STATEMENTS, CONDITIONALS AND FOR LOOPS
     Makefile inclusion, conditional structures and for loops  reminiscent of
     the C programming language are provided in make.  All such structures are
     identified by a line beginning with a single dot (`.') character.  Files
     are included with either .include <file> or .include "file".  Variables
     between the angle brackets or double quotes are expanded to form the file
     name.  If angle brackets are used, the included makefile is expected to
     be in the system makefile directory.  If double quotes are used, the
     including makefile's directory and any directories specified using the -I
     option are searched before the system makefile directory.  For compati-
     bility with other versions of make `include file ...' is also accepted.
     If the include statement is written as .-include or as .sinclude then
     errors locating and/or opening include files are ignored.

     Conditional expressions are also preceded by a single dot as the first
     character of a line.  The possible conditionals are as follows:

     .error message
             The message is printed along with the name of the makefile and
             line number, then make will exit.

     .export variable ...
             Export the specified global variable.  If no variable list is
             provided, all globals are exported except for internal variables
             (those that start with `.').  This is not affected by the -X
             flag, so should be used with caution.  For compatibility with
             other make programs `export variable=value' is also accepted.

             Appending a variable name to .MAKE.EXPORTED is equivalent to
             exporting a variable.

     .export-env variable ...
             The same as `.export', except that the variable is not appended
             to .MAKE.EXPORTED.  This allows exporting a value to the environ-
             ment which is different from that used by make internally.

     .info message
             The message is printed along with the name of the makefile and
             line number.

     .undef variable
             Un-define the specified global variable.  Only global variables
             may be un-defined.

     .unexport variable ...
             The opposite of `.export'.  The specified global variable will be
             removed from .MAKE.EXPORTED.  If no variable list is provided,
             all globals are unexported, and .MAKE.EXPORTED deleted.

     .unexport-env
             Unexport all globals previously exported and clear the environ-
             ment inherited from the parent.  This operation will cause a mem-
             ory leak of the original environment, so should be used spar-
             ingly.  Testing for .MAKE.LEVEL being 0, would make sense.  Also
             note that any variables which originated in the parent environ-
             ment should be explicitly preserved if desired.  For example:

                   .if ${.MAKE.LEVEL} == 0
                   PATH := ${PATH}
                   .unexport-env
                   .export PATH
                   .endif

             Would result in an environment containing only `PATH', which is
             the minimal useful environment.  Actually `.MAKE.LEVEL' will also
             be pushed into the new environment.

     .warning message
             The message prefixed by `warning:' is printed along with the name
             of the makefile and line number.

     .if [!]expression [operator expression ...]
             Test the value of an expression.

     .ifdef [!]variable [operator variable ...]
             Test the value of a variable.

     .ifndef [!]variable [operator variable ...]
             Test the value of a variable.

     .ifmake [!]target [operator target ...]
             Test the target being built.

     .ifnmake [!] target [operator target ...]
             Test the target being built.

     .else   Reverse the sense of the last conditional.

     .elif [!] expression [operator expression ...]
             A combination of `.else' followed by `.if'.

     .elifdef [!]variable [operator variable ...]
             A combination of `.else' followed by `.ifdef'.

     .elifndef [!]variable [operator variable ...]
             A combination of `.else' followed by `.ifndef'.

     .elifmake [!]target [operator target ...]
             A combination of `.else' followed by `.ifmake'.

     .elifnmake [!]target [operator target ...]
             A combination of `.else' followed by `.ifnmake'.

     .endif  End the body of the conditional.

     The operator may be any one of the following:

     ||     Logical OR.

     &&     Logical AND; of higher precedence than ``||''.

     As in C, make will only evaluate a conditional as far as is necessary to
     determine its value.  Parentheses may be used to change the order of
     evaluation.  The boolean operator `!' may be used to logically negate an
     entire conditional.  It is of higher precedence than `&&'.

     The value of expression may be any of the following:

     defined  Takes a variable name as an argument and evaluates to true if
              the variable has been defined.

     make     Takes a target name as an argument and evaluates to true if the
              target was specified as part of make's command line or was
              declared the default target (either implicitly or explicitly,
              see .MAIN) before the line containing the conditional.

     empty    Takes a variable, with possible modifiers, and evaluates to true
              if the expansion of the variable would result in an empty
              string.

     exists   Takes a file name as an argument and evaluates to true if the
              file exists.  The file is searched for on the system search path
              (see .PATH).

     target   Takes a target name as an argument and evaluates to true if the
              target has been defined.

     commands
              Takes a target name as an argument and evaluates to true if the
              target has been defined and has commands associated with it.

     Expression may also be an arithmetic or string comparison.  Variable
     expansion is performed on both sides of the comparison, after which the
     integral values are compared.  A value is interpreted as hexadecimal if
     it is preceded by 0x, otherwise it is decimal; octal numbers are not sup-
     ported.  The standard C relational operators are all supported.  If after
     variable expansion, either the left or right hand side of a `==' or `!='
     operator is not an integral value, then string comparison is performed
     between the expanded variables.  If no relational operator is given, it
     is assumed that the expanded variable is being compared against 0 or an
     empty string in the case of a string comparison.

     When make is evaluating one of these conditional expressions, and it
     encounters a (white-space separated) word it doesn't recognize, either
     the ``make'' or ``defined'' expression is applied to it, depending on the
     form of the conditional.  If the form is `.ifdef', `.ifndef', or `.if'
     the ``defined'' expression is applied.  Similarly, if the form is
     `.ifmake' or `.ifnmake', the ``make'' expression is applied.

     If the conditional evaluates to true the parsing of the makefile contin-
     ues as before.  If it evaluates to false, the following lines are
     skipped.  In both cases this continues until a `.else' or `.endif' is
     found.

     For loops are typically used to apply a set of rules to a list of files.
     The syntax of a for loop is:

     .for variable [variable ...] in expression
     <make-rules>
     .endfor

     After the for expression is evaluated, it is split into words.  On each
     iteration of the loop, one word is taken and assigned to each variable,
     in order, and these variables are substituted into the make-rules inside
     the body of the for loop.  The number of words must come out even; that
     is, if there are three iteration variables, the number of words provided
     must be a multiple of three.

COMMENTS
     Comments begin with a hash (`#') character, anywhere but in a shell com-
     mand line, and continue to the end of an unescaped new line.  This can be
     used to a great effect to comment out continued sections of a makefile
     but it can also lead to very subtle, and possibly difficult to spot,
     errors for that same reason.  Please observe some actually encountered
     problems:

           |                    |                    |
           |                    |                    |
           |                    |                    |
           bar                  |      baz           |  target: source

SPECIAL SOURCES (ATTRIBUTES)
     .EXEC     Target is never out of date, but always execute commands any-
               way.

     .IGNORE   Ignore any errors from the commands associated with this tar-
               get, exactly as if they all were preceded by a dash (`-').

     .MADE     Mark all sources of this target as being up-to-date.

     .MAKE     Execute the commands associated with this target even if the -n
               or -t options were specified.  Normally used to mark recursive
               makes.  Single lines from rule's commands may be marked for
               similar treatment by prepending them with `+'.

     .META     Create a meta file for the target, even if it is flagged as
               .PHONY, .MAKE, or .SPECIAL.  Usage in conjunction with .MAKE is
               the most likely case.  In "meta" mode, the target is out-of-
               date if the meta file is missing.

     .NOMETA   Do not create a meta file for the target.  Meta files are also
               not created for .PHONY, .MAKE, or .SPECIAL targets.

     .NOMETA_CMP
               Ignore differences in commands when deciding if target is out
               of date.  This is useful if the command contains a value which
               always changes.  If the number of commands change, though, the
               target will still be out of date.  The same effect applies to
               any command line that uses the variable .OODATE, which can be
               used for that purpose even when not otherwise needed or
               desired:


                     skip-compare-for-some:
                             @echo this will be compared
                             @echo this will not ${.OODATE:M.NOMETA_CMP}
                             @echo this will also be compared

               The :M pattern suppresses any expansion of the unwanted vari-
               able.

     .NOPATH   Do not search for the target in the directories specified by
               .PATH.

     .NOTMAIN  Normally make selects the first target it encounters as the
               default target to be built if no target was specified.  This
               source prevents this target from being selected.

     .OPTIONAL
               If a target is marked with this attribute and make can't figure
               out how to create it, it will ignore this fact and assume the
               file isn't needed or already exists.

     .PHONY    The target does not correspond to an actual file; it is always
               considered to be out of date, and will not be created with the
               -t option.  Suffix-transformation rules are not applied to
               .PHONY targets.

               As a note of historical interest, a dependency on a target
               called ``FORCE'' or ``FRC'' has been used to force make always
               run the commands of a target, instead of the in all ways supe-
               rior .PHONY.  This dependency will then itself defined without
               dependencies or commands.  As long as a file by that name does
               not exist, the target will always be considered to be out of
               date and force targets depending on it to be re-made.

     .PRECIOUS
               When make is interrupted, it normally removes any partially
               made targets.  This source prevents the target from being
               removed.

     .RECURSIVE
               Synonym for .MAKE.

     .SILENT   Do not echo any of the commands associated with this target,
               exactly as if they all were preceded by an at sign (`@').

     .USE      Turn the target into make's version of a macro.  When the tar-
               get is used as a source for another target, the other target
               acquires the commands, sources, and attributes (except for
               .USE) of the source.  If the target already has commands, the
               .USE target's commands are appended to them.

     .USEBEFORE
               Exactly like .USE, but prepend the .USEBEFORE target commands
               to the target.

     .WAIT     If .WAIT appears in a dependency line, the sources that precede
               it are made before the sources that succeed it in the line.
               Since the dependents of files are not made until the file
               itself could be made, this also stops the dependents being
               built unless they are needed for another branch of the depen-
               dency tree.  So given:

               x: a .WAIT b
                       echo x
               a:
                       echo a
               b: b1
                       echo b
               b1:
                       echo b1

               the output is always `a', `b1', `b', `x'.
               The ordering imposed by .WAIT is only relevant for parallel
               makes.

SPECIAL TARGETS
     Special targets may not be included with other targets, i.e. they must be
     the only target specified.

     .BEGIN   Any command lines attached to this target are executed before
              anything else is done.

     .DEFAULT
              This is sort of a .USE rule for any target (that was used only
              as a source) that make can't figure out any other way to create.
              Only the shell script is used.  The .IMPSRC variable of a target
              that inherits .DEFAULT's commands is set to the target's own
              name.

     .END     Any command lines attached to this target are executed after
              everything else is done.

     .ERROR   Any command lines attached to this target are executed when
              another target fails.  The .ERROR_TARGET variable is set to the
              target that failed.  See also MAKE_PRINT_VAR_ON_ERROR.

     .IGNORE  Mark each of the sources with the .IGNORE attribute.  If no
              sources are specified, this is the equivalent of specifying the
              -i option.

     .INTERRUPT
              If make is interrupted, the commands for this target will be
              executed.

     .MAIN    If no target is specified when make is invoked, this target will
              be built.

     .MAKEFLAGS
              This target provides a way to specify flags for make when the
              makefile is used.  The flags are as if typed to the shell,
              though the -f option will have no effect.

     .NOPATH  Apply the .NOPATH attribute to any specified sources.

     .NOTPARALLEL
              Disable parallel mode.

     .NO_PARALLEL
              Synonym for .NOTPARALLEL, for compatibility with other pmake
              variants.

     .NULL    This special target is deprecated! It will go away as soon as
              pattern rules are implemented.

              The source of this target is a suffix listed in .SUFFIXES.  It
              tells make to pretend that targets which have no other known
              suffix have that suffix.  This is relevant when suffix transfor-
              mation rules are tried, and has the following two aspects (.s1
              is the null suffix):

                    remove a suffix: if the target `foo' is needed, the trans-
                    formation rule `.s2.s1' can be used to make it from
                    `foo.s2'.  The .TARGET and .PREFIX local variables are set
                    to `foo'.

                    add a suffix: if the target `foo.s2' is needed, the trans-
                    formation rule `.s1.s2' can be used to make it from `foo'.
                    The .IMPSRC local variable is set to `foo'.

              This feature might be easier to understand, if you think of
              `.s1' as a way of explicitly writing `'.

              Looking closely you will notice that the first, suffix removal
              aspect is a limited version of single suffix transformation
              rules.  It abuses double suffix rules and only works with one
              source `suffix'.  New makefiles should use single suffix rules
              and old ones should migrate to them.  Using both at the same
              time won't crash make, but you're aiming a gun at your own foot.
              To protect your foot, the rules followed in that case are not
              laid out here, you need to read the source code.

              This special target is only currently retained because of the
              second, suffix adding aspect, even if that too abuses double
              suffix rules.  There is no substitute before pattern rules are
              implemented.  To use this feature in this case, it is strongly
              suggested to use a verbose suffix that is not a real or imagin-
              able one in your project, for example `.NOSUFFIX'.

     .ORDER   The named targets are made in sequence.  This ordering does not
              add targets to the list of targets to be made.  Since the depen-
              dents of a target do not get built until the target itself could
              be built, unless `a' is built by another part of the dependency
              graph, the following is a dependency loop:

              .ORDER: b a
              b: a

              The ordering imposed by .ORDER is only relevant for parallel
              makes.

     .PATH    The sources are directories which are to be searched for files
              not found in the current directory.  If no sources are speci-
              fied, any previously specified directories are deleted.  If the
              source is the special .DOTLAST target, then the current working
              directory is searched last.

     .PATH.suffix
              Like .PATH but applies only to files with a particular suffix.
              The suffix must have been previously declared with .SUFFIXES.

     .PHONY   Apply the .PHONY attribute to any specified sources.

     .PRECIOUS
              Apply the .PRECIOUS attribute to any specified sources.  If no
              sources are specified, the .PRECIOUS attribute is applied to
              every target in the file.

     .SHELL   Sets the shell that make will use to execute commands.  The
              sources are a set of field=value pairs.

              name        This is the minimal specification, used to select
                          one of the builtin shell specs; sh, ksh, and csh.

              path        Specifies the path to the shell.

              hasErrCtl   Indicates whether the shell supports exit on error.

              check       The command to turn on error checking.

              ignore      The command to disable error checking.

              echo        The command to turn on echoing of commands executed.

              quiet       The command to turn off echoing of commands exe-
                          cuted.

              filter      The output to filter after issuing the quiet com-
                          mand.  It is typically identical to quiet.

              errFlag     The flag to pass the shell to enable error checking.

              echoFlag    The flag to pass the shell to enable command echo-
                          ing.

              newline     The string literal to pass the shell that results in
                          a single newline character when used outside of any
                          quoting characters.
              Example:

              .SHELL: name=ksh path=/bin/ksh hasErrCtl=true \
                      check="set -e" ignore="set +e" \
                      echo="set -v" quiet="set +v" filter="set +v" \
                      echoFlag=v errFlag=e newline="'\n'"

     .SILENT  Apply the .SILENT attribute to any specified sources.  If no
              sources are specified, the .SILENT attribute is applied to every
              command in the file.

     .STALE   This target gets run when a dependency file contains stale
              entries, having .ALLSRC set to the name of that dependency file.

     .SUFFIXES
              Each source specifies a known suffix to make.  It allows the
              creation of suffix transformation rules.  A rule that looks like
              a transformation rule is a regular rule if it is not composed of
              known suffixes.  If no sources are specified, all known suffixes
              are forgotten.

              There is a built-in list of suffixes and related transformation
              rules in make.  Clearing the suffix list does not remove the
              corresponding rules and they become active again if the related
              suffixes are made known again.  In fact, there is no way other
              than the -r command line option to completely remove the built-
              in rules.  It is possible to nullify it with an explicit no-op
              rule (it will run, but won't do anything) or redefine it.

              Example:

              .SUFFIXES:        # Forget all suffixes
              .SUFFIXES: .c .o  # Re-activate .c and .o
              .c: ;             # Nullify (the semicolon is mandatory)
              .c.o:             # Replace
                      cc -o ${.TARGET} -c ${.IMPSRC}

              POSIX compatible suffixes start with a period and contain no
              slashes or other periods.  In this implementation the amount and
              the location of periods is not restricted: there may be none or
              more than one period, anywhere in the suffix.

ENVIRONMENT
     make uses the following environment variables, if they exist: MACHINE,
     MACHINE_ARCH, MAKE, MAKEFLAGS, MAKEOBJDIR, MAKEOBJDIRPREFIX, MAKESYSPATH,
     PWD, and TMPDIR.

     MAKEOBJDIRPREFIX and MAKEOBJDIR may only be set in the environment or on
     the command line to make and not as makefile variables; see the descrip-
     tion of `.OBJDIR' for more details.

FILES
     .depend        list of dependencies
     Makefile       list of dependencies
     makefile       list of dependencies
     sys.mk         system makefile
     /usr/share/mk  system makefile directory

COMPATIBILITY
     The basic make syntax is compatible between different versions of make,
     however the special variables, variable modifiers and conditionals are
     not.

     The way that parallel makes are scheduled changed in NetBSD 4.0 so that
     .ORDER and .WAIT apply recursively to the dependent nodes.  The algo-
     rithms used may change again in the future.

     The way that .for loop variables are substituted changed after NetBSD 5.0
     so that they still appear to be variable expansions.  In particular this
     stops them being treated as syntax, and removes some obscure problems
     using them in .if statements.

SEE ALSO
     mkdep(1)

HISTORY
     A make command appeared in Version 7 AT&T UNIX.  This make implementation
     is based on Adam De Boor's pmake program which was written for Sprite at
     Berkeley.  It was designed to be a parallel distributed make running jobs
     on different machines using a daemon called ``customs''.

BUGS
     The make syntax is difficult to parse without actually acting of the
     data.  For instance finding the end of a variable use should involve
     scanning each the modifiers using the correct terminator for each field.
     In many places make just counts {} and () in order to find the end of a
     variable expansion.

     There is no way of escaping a space character in a filename.

NetBSD 7.0                      August 28, 2014                     NetBSD 7.0

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