TR(1) Commands and Applications TR(1)
tr - translate characters
tr [-cs] string1 string2
tr [-c] -d string1
tr [-c] -s string1
tr [-c] -ds string1 string2
The tr utility copies the standard input to the standard output with
substitution 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
-d The -d option causes characters to be deleted from the
-s The -s option squeezes multiple occurrences of the char-
acters listed in the last operand (either string1 or
string2) in the input into a single instance of the char-
acter. This occurs after all deletion and translation is
In the first synopsis form, the characters in string1 are translated
into the characters in string2 where the first character in string1 is
translated into the first character in string2 and so on. If string1
is longer than string2, the last character found in string2 is dupli-
cated until string1 is exhausted.
In the second synopsis form, the characters in string1 are deleted from
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:
Any character not described by one of the following con-
ventions 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.
A backslash followed by certain special characters maps
to special values.
\a <alert character>
\r <carriage return>
\v <vertical tab>
A backslash followed by any other character maps to that charac-
c1-c2 Represents the range of characters between the range end-
Represents all characters belonging to the defined char-
acter class. Class names are:
alnum <alphanumeric characters>
alpha <alphabetic characters>
blank <\t, '' ''>
cntrl <control characters>
digit <numeric characters>
graph <graphic characters>
lower <lower-case alphabetic characters>
print <printable characters>
punct <punctuation characters>
space <\t, \n, \v, \f, \r, '' ''>
upper <upper-case characters>
xdigit <hexadecimal characters>
With the exception of the ''upper'' and ''lower'' classes, char-
acters in the classes are in unspecified order. In the
''upper'' and ''lower'' classes, characters are entered in
For specific information as to which ASCII characters are
included in these classes, see ctype(3) and related manual
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 characters are ordered in ascending sequence.
Otherwise, they are ordered after their encoded values.
An example of an equivalence class might be ''c'' and
''ch'' in Spanish; English has no equivalence classes.
Note: because the functions in locale.h are not imple-
mented for the Apple IIGS, English is the only supported
[#*n] Represents n repeated occurrences of the character repre-
sented 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 inter-
preted as a decimal value.
The tr utility exits 0 on success, and >0 if an error occurs.
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
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 com-
mand ''tr -d [a-z]'', the characters ''['' and '']'' will be included
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
errors, for example, the -c and -s options were ignored unless two
strings were specified. This implementation will not permit illegal
The tr utility is expected to be POSIX.2 compatible. It should be
noted that the feature wherein the last character of string2 is dupli-
cated 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 manual page documents tr version 2.0.
This command was ported from FreeBSD source code for distribution with
Version 1.0 (November 3, 1994) of tr was written by Thomas. R. Wyant
III and distributed as a separate package compatible with GNO and ORCA.
GNO August 1997 TR(1)
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