TR(1) BSD General Commands Manual TR(1)
NAME
tr -- translate characters
SYNOPSIS
tr [-Ccsu] string1 string2
tr [-Ccu] -d string1
tr [-Ccu] -s string1
tr [-Ccu] -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 Complement the set of characters in string1, that is ``-C ab''
includes every character except for ``a'' and ``b''.
-c Same as -C but complement the set of byte values in string1.
-d Delete characters in string1 from the input.
-s Squeeze 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.
-u Guarantee that any output is unbuffered.
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
\b
\f
\n
\r
\t
\v
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
alpha
cntrl
digit
graph
lower
print
punct
space
upper
xdigit
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 ASCI characters are
included in these classes, see ctype(3) and related manual
pages.
[=equiv=] Represents all characters belonging to the same equivalence
class as equiv, ordered by their encoded values.
[#*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.
ENVIRONMENT
The LANG, LCAL, LCTYPE and LCOLATE environment variables affect
the execution of tr as described in environ(7).
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
Remove diacritical marks from all accented variants of the letter `e':
tr "[=e=]" "e"
DIAGNOSTICS
The tr utility exits 0 on success, and >0 if an error occurs.
COMPATIBILITY
System V has historically implemented character ranges using the syntax
``[c-c]'' instead of the ``c-c'' used by historic BSD implementations and
standardized by POSIX. System V 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 ``['' 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 included in the dele-
tion 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
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 conforms to IE Std 1003.1-2001 (``POSIX.1'').
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. The -u option is an extension to the IE Std
1003.1-2001 (``POSIX.1'') standard.
BSD October 11, 1997 BSD
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