tr [-cs] string1 string2
      [-c] -d string1
      [-c] -s string1
      [-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 in-
             put 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 se-
                quence 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.

                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 as-
                cending order.

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

     [=equiv=]  Represents all characters or collating (sorting) elements be-
                longing 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 be 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.

     The tr utility 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

     map the ``['' character in string1 to the ``['' character 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 in-
     cluded in the deletion or compression list which would not have happened
     under an historic System V 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 er-
     rors, for example, the -c and -s options were ignored unless two strings
     were specified.  This implementation will not permit illegal syntax.

STANDARDS

     The tr utility is expected to be IEEE Std1003.2 (``POSIX'') compatible.
     It should be noted that the feature wherein the last character of string2
     is duplicated if string2 has less characters than string1 is permitted by
     POSIX but is not required.  Shell scripts attempting to be portable to
     other POSIX systems should use the ``[#*]'' convention instead of relying
     on this behavior.

BSD Experimental                 June 6, 1993                                3