.\" Copyright (c) 1991 Regents of the University of California.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" the Institute of Electrical and Electronics Engineers, Inc.
.\"
.\" %sccs.include.redist.man%
.\"
.\"     @(#)tr.1	6.5 (Berkeley) %G%
.\"
.Dd 
.Dt TR 1
.Os
.Sh NAME
.Nm tr
.Nd translate characters
.Sh SYNOPSIS
.Nm tr
.Op Fl c
.Op Fl d | Fl s
.Ar string1 string2
.Sh DESCRIPTION
The tr utility copies the standard input to the standard
output with substitution or deletion of selected characters.
The options specified and the
.Ar string1
and
.Ar string2
operands
control translations that occur while copying characters.
.Pp
The following options are available:
.Bl -tag -width Ds
.It Fl c
Complements the set of characters in string1 with
respect to the universe of characters whose
.Tn ISO
646
[4] codes are 00 through 0377 octal.
.It Fl d
Deletes all input characters in
.Ar string1 .
.It Fl s
Squeezes all output strings of one or more
instances of a single character in
.Ar string2
to a
single instance of that character.
Input characters found
in
.Ar string1
are mapped into the corresponding characters
of
.Ar string2 .
When
.Ar string2
is shorter than
.Ar string1 , string2
is extended to the length of
.Ar string1
by duplicating the last character of
.Ar string2 .
If
.Ar string2
is explicitly a string of zero
length,
.Ar string2
is padded with
.Tn NUL
characters.
.El
.Pp
The following operands are available:
.Bl -tag -width stringx
.It Ar string1
.It Ar string2
Translation character strings.
.El
.Pp
.Pp
If
the
.Fl c
option is given in conjunction with the
.Fl d
option, then only those characters found in
.Ar string1
is copied to the standard output.
.Pp
The following conventions can be used in
.Ar string1
or
.Ar string2
or both to specify characters, character ranges, character
classes, or collating elements:
.Bl -tag -width [[:equiv:]]
.It character
Represents that character.
.It \eoctal
A backslash followed by 1, 2, or 3 octal
digits represents a character with that
encoded value.
If a \eoctal sequence is
followed by digits, the backslash and up to
three digits are interpreted to prepare a
character; subsequent digits are interpreted
as individual characters.
.It \echaracter
A backslash followed by any character except
an octal digit represents that character.
.It [c-c]
Represents the range of ordered elements
between the range endpoints, inclusive.
.\" ; as
.\" defined by the current setting of the
.\" setlocale() category
.\" .Em LC_COLLATE .
.\" The collating
.\" elements are ordered in ascending collating
.\" sequence, and the first endpoint shall precede
.\" the second in the collating sequence.
.It [[:class:]]
Represents all characters belonging to the
defined character class.
.\" as defined by the
.\" current setting of the setlocale() category
.\" .Ev LC_CTYPE .
Allowable names for class are:
.Bl -column alpha upper lower digit xdigit -offset indent
alpha  upper  lower  digit  xdigit  alnum
space  punct  print  graph  cntrl
.El
.Pp
The characters placed in ascending order.
.\" .Em LC_COLLATE .
.\" (Characters not defined in the
.\" current collating sequence are ordered
.\" according to the collation sequence's rules
.\" for ordering of undefined characters.)
.It [[=equiv=]]
Represents all characters or collating (sorting)
elements belonging to the same equivalence class
as equiv.
.\" 
.\" 
.\" .Em LC_COLLATE .
If
there is a secondary ordering within the
equivalence class, the characters are ordered
in ascending sequence.
Otherwise, they are
ordered after their encoded values. 
.It [[.cs.]]
Represents a collating symbol.
Multicharacter
collating symbols shall be represented as
collating symbols to distinguish them from a
string of the same characters.
.It [x*n]
Represents n repeated occurrences of the
character or collating symbol x.
This
expression is only valid when it occurs in
.Ar string2 .
If n is omitted or is zero, it is
be interpreted as large enough to extend the
.Ar string2 Ns -based
sequence to the length of the
.Ar string1 Ns -based
sequence.
If n has a leading
zero, it shall be interpreted as an octal
value.
Otherwise, it shall be interpreted as
a decimal value.
.El
.Pp
Characters belonging to an equivalence class occupy the same
position in the sequence, ordered after secondary ordering.
.Pp
The
.Nm tr
utility exits with one of the following values:
.Bl -tag -width Ds
.It 0
All input was processed successfully.
.It 1
An error occurred.
.El
.Sh STANDARDS
The
.Nm tr
utility is expected to be
.Tn POSIX
1003.2 compatible.