TR(1)                   NetBSD General Commands Manual                   TR(1)

NAME
     tr -- translate characters

SYNOPSIS
     tr [-cs] string1 string2
     tr [-c] -d string1
     tr [-c] -s string1
     tr [-c] -ds string1 string2

DESCRIPTION
     The tr utility copies the standard input to the standard output with sub-
     stitution or deletion of selected characters.

     The following options are available:

     -c      Complements the set of characters in string1, that is -c ab
             includes every character except for `a' and `b'.

     -d      The -d option causes characters to be deleted from the input.

     -s      The -s option squeezes multiple occurrences of the characters
             listed in the last operand (either string1 or string2) in the
             input into a single instance of the character.  This occurs after
             all deletion and translation is completed.

     In the first synopsis form, the characters in string1 are translated into
     the characters in string2 where the first character in string1 is trans-
     lated into the first character in string2 and so on.  If string1 is
     longer than string2, the last character found in string2 is duplicated
     until string1 is exhausted.

     In the second synopsis form, the characters in string1 are deleted from
     the input.

     In the third synopsis form, the characters in string1 are compressed as
     described for the -s option.

     In the fourth synopsis form, the characters in string1 are deleted from
     the input, and the characters in string2 are compressed as described for
     the -s option.

     The following conventions can be used in string1 and string2 to specify
     sets of characters:

     character  Any character not described by one of the following conven-
                tions represents itself.

     \octal     A backslash followed by 1, 2 or 3 octal digits represents a
                character with that encoded value.  To follow an octal
                sequence with a digit as a character, left zero-pad the octal
                sequence to the full 3 octal digits.

     \character
                A backslash followed by certain special characters maps to
                special values.


                \a    <alert character>
                \b    <backspace>
                \f    <form-feed>
                \n    <newline>
                \r    <carriage return>
                \t    <tab>
                \v    <vertical tab>

                A backslash followed by any other character maps to that char-
                acter.

     c-c        Represents the range of characters between the range end-
                points, inclusively.

     [:class:]  Represents all characters belonging to the defined character
                class.  Class names are:


                alnum     <alphanumeric characters>
                alpha     <alphabetic characters>
                blank     <blank characters>
                cntrl     <control characters>
                digit     <numeric characters>
                graph     <graphic characters>
                lower     <lower-case alphabetic characters>
                print     <printable characters>
                punct     <punctuation characters>
                space     <space characters>
                upper     <upper-case characters>
                xdigit    <hexadecimal characters>

                With the exception of the ``upper'' and ``lower'' classes,
                characters in the classes are in unspecified order.  In the
                ``upper'' and ``lower'' classes, characters are entered in
                ascending order.

                For specific information as to which ASCII characters are
                included in these classes, see ctype(3) and related manual
                pages.

     [=equiv=]  Represents all characters or collating (sorting) elements
                belonging to the same equivalence class as equiv.  If there is
                a secondary ordering within the equivalence class, the charac-
                ters are ordered in ascending sequence.  Otherwise, they are
                ordered after their encoded values.  An example of an equiva-
                lence class might be ``c'' and ``ch'' in Spanish; English has
                no equivalence classes.

     [#*n]      Represents n repeated occurrences of the character represented
                by #.  This expression is only valid when it occurs in
                string2.  If n is omitted or is zero, it is interpreted as
                large enough to extend string2 sequence to the length of
                string1.  If n has a leading zero, it is interpreted as an
                octal value, otherwise, it's interpreted as a decimal value.

EXIT STATUS
     tr exits 0 on success, and >0 if an error occurs.

EXAMPLES
     The following examples are shown as given to the shell:

     Create a list of the words in file1, one per line, where a word is taken
     to be a maximal string of letters:

           tr -cs "[:alpha:]" "\n" < file1

     Translate the contents of file1 to upper-case:

           tr "[:lower:]" "[:upper:]" < file1

     Strip out non-printable characters from file1:

           tr -cd "[:print:]" < file1

COMPATIBILITY
     AT&T System V UNIX has historically implemented character ranges using
     the syntax ``[c-c]'' instead of the ``c-c'' used by historic BSD imple-
     mentations and standardized by POSIX.  AT&T System V UNIX shell scripts
     should work under this implementation as long as the range is intended to
     map in another range, i.e. the command

     tr [a-z] [A-Z]

     will work as it will map the `[' character in string1 to the `[' charac-
     ter in string2.  However, if the shell script is deleting or squeezing
     characters as in the command

     tr -d [a-z]

     the characters `[' and `]' will be included in the deletion or compres-
     sion list which would not have happened under an historic AT&T System V
     UNIX implementation.  Additionally, any scripts that depended on the
     sequence ``a-z'' to represent the three characters `a', `-', and `z' will
     have to be rewritten as ``a\-z''.

     The tr utility has historically not permitted the manipulation of NUL
     bytes in its input and, additionally, stripped NUL's from its input
     stream.  This implementation has removed this behavior as a bug.

     The tr utility has historically been extremely forgiving of syntax
     errors, for example, the -c and -s options were ignored unless two
     strings were specified.  This implementation will not permit illegal syn-
     tax.

STANDARDS
     The tr utility is expected to be IEEE Std 1003.2 (``POSIX.2'') compati-
     ble.  It should be noted that the feature wherein the last character of
     string2 is duplicated if string2 has less characters than string1 is per-
     mitted by POSIX but is not required.  Shell scripts attempting to be por-
     table to other POSIX systems should use the ``[#*]'' convention instead
     of relying on this behavior.

BUGS
     tr was originally designed to work with US-ASCII.  Its use with character
     sets that do not share all the properties of US-ASCII, e.g., a symmetric
     set of upper and lower case characters that can be algorithmically con-
     verted one to the other, may yield unpredictable results.

     tr should be internationalized.

NetBSD 6.0                      March 23, 2004                      NetBSD 6.0

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