tr - translate characters
/usr/bin/tr [-cs] string1 string2
/usr/bin/tr -s | -d [-c] string1
/usr/bin/tr -ds [-c] string1 string2
/usr/xpg4/bin/tr [-cs] string1 string2
/usr/xpg4/bin/tr -s | -d [-c] string1
/usr/xpg4/bin/tr -ds [-c] string1 string2
The tr utility copies the standard input to the standard
output with substitution or deletion of selected characters.
The options specified and the string1 and string2 operands
control translations that occur while copying characters and
single-character collating elements.
The following options are supported:
-c Complements the set of characters specified by
-d Deletes all occurrences of input characters that are
specified by string1.
-s Replaces instances of repeated characters with a sin-
When the -d option is not specified:
o Each input character found in the array specified by
string1 is replaced by the character in the same rela-
tive position in the array specified by string2. When
the array specified by string2 is shorter that the one
specified by string1, the results are unspecified.
o If the -c option is specified, the complements of the
characters specified by string1 (the set of all char-
acters in the current character set, as defined by the
current setting of LC_CTYPE, except for those actually
specified in the string1 operand) are placed in the
array in ascending collation sequence, as defined by
the current setting of LC_COLLATE.
o Because the order in which characters specified by
character class expressions or equivalence class
expressions is undefined, such expressions should only
be used if the intent is to map several characters
into one. An exception is case conversion, as
When the -d option is specified:
o Input characters found in the array specified by
string1 will be deleted.
o When the -c option is specified with -d, all charac-
ters except those specified by string1 will be
deleted. The contents of string2 will be ignored,
unless the -s option is also specified.
o The same string cannot be used for both the -d and the
-s option; when both options are specified, both
string1 (used for deletion) and string2 (used for
squeezing) are required.
When the -s option is specified, after any deletions or
translations have taken place, repeated sequences of the
same character will be replaced by one occurrence of the
same character, if the character is found in the array
specified by the last operand. If the last operand contains
a character class, such as the following example:
tr -s '[:space:]'
the last operand's array will contain all of the characters
in that character class. However, in a case conversion, as
described previously, such as
tr -s '[:upper:]' '[:lower:]'
the last operand's array will contain only those characters
defined as the second characters in each of the toupper or
tolower character pairs, as appropriate. (See toupper(3C)
An empty string used for string1 or string2 produces unde-
The following operands are supported:
Translation control strings. Each string represents a
set of characters to be converted into an array of
characters used for the translation.
The operands string1 and string2 (if specified) define two
arrays of characters. The constructs in the following list
can be used to specify characters or single-character col-
lating elements. If any of the constructs result in multi-
character collating elements, tr will exclude, without a
diagnostic, those multi-character elements from the result-
Any character not described by one of the conventions
below represents itself.
Octal sequences can be used to represent characters
with specific coded values. An octal sequence consists
of a backslash followed by the longest sequence of
one-, two-, or three-octal-digit characters
(01234567). The sequence causes the character whose
encoding is represented by the one-, two- or three-
digit octal integer to be placed into the array.
Multi-byte characters require multiple, concatenated
escape sequences of this type, including the leading \
for each byte.
The backslash-escape sequences \a, \b, \f, \n, \r, \t,
and \v are supported. The results of using any other
character, other than an octal digit, following the
backslash are unspecified.
[c-c] Represents the range of collating elements between the
range endpoints, inclusive, as defined by the current
setting of the LC_COLLATE locale category. The start-
ing endpoint must precede the second endpoint in the
current collation order. The characters or collating
elements in the range are placed in the array in
ascending collation sequence.
Represents all characters belonging to the defined
character class, as defined by the current setting of
the LC_CTYPE locale category. The following character
class names will be accepted when specified in
alnum blank digit lower punct upper
alpha cntrl graph print space xdigit
In addition, character class expressions of the form
[:name:] are recognized in those locales where the
name keyword has been given a charclass definition in
the LC_CTYPE category.
Note: /usr/bin/tr supports character class expressions
only in singlebyte locales. Use /usr/xpg4/bin/tr to
support these expressions in any locale.
When both the -d and -s options are specified, any of
the character class names will be accepted in string2.
Otherwise, only character class names lower or upper
are valid in string2 and then only if the correspond-
ing character class upper and lower, respectively, is
specified in the same relative position in string1.
Such a specification is interpreted as a request for
case conversion. When [:lower:] appears in string1 and
[:upper:] appears in string2, the arrays will contain
the characters from the toupper mapping in the
LC_CTYPE category of the current locale. When
[:upper:] appears in string1 and [:lower:] appears in
string2, the arrays will contain the characters from
the tolower mapping in the LC_CTYPE category of the
current locale. The first character from each mapping
pair will be in the array for string1 and the second
character from each mapping pair will be in the array
for string2 in the same relative position.
Except for case conversion, the characters specified
by a character class expression are placed in the
array in an unspecified order.
If the name specified for class does not define a
valid character class in the current locale, the
behavior is undefined.
Represents all characters or collating elements
belonging to the same equivalence class as equiv, as
defined by the current setting of the LC_COLLATE
locale category. An equivalence class expression is
allowed only in string1, or in string2 when it is
being used by the combined -d and -s options. The
characters belonging to the equivalence class are
placed in the array in an unspecified order.
[x*n] Represents n repeated occurrences of the character x.
Because this expression is used to map multiple char-
acters to one, it is only valid when it occurs in
string2. If n is omitted or is 0, it is interpreted as
large enough to extend the string2-based sequence to
the length of the string1-based sequence. If n has a
leading 0, it is interpreted as an octal value. Other-
wise, it is interpreted as a decimal value.
See largefile(5) for the description of the behavior of tr
when encountering files greater than or equal to 2 Gbyte ( 2
Example 1: Creating a list of words
The following example creates a list of all words in file1,
one per line in file2, where a word is taken to be a maximal
string of letters.
tr -cs "[:alpha:]" "[\n*]" <file1 >file2
Example 2: Translating characters
This example translates all lower-case characters in file1
to upper-case and writes the results to standard output.
tr "[:lower:]" "[:upper:]" <file1
Notice that the caveat expressed in the corresponding exam-
ple in XPG3 is no longer in effect. This case conversion is
now a special case that employs the tolower and toupper
classifications, ensuring that proper mapping is accom-
plished (when the locale is correctly defined).
Example 3: Identifying equivalent characters
This example uses an equivalence class to identify accented
variants of the base character e in file1, which are
stripped of diacritical marks and written to file2.
tr "[=e=]" e <file1 >file2
See environ(5) for descriptions of the following environment
variables that affect the execution of tr: LANG, LC_ALL,
LC_COLLATE, LC_CTYPE, LC_MESSAGES, and NLSPATH.
The following exit values are returned:
0 All input was processed successfully.
>0 An error occurred.
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Availability | SUNWcsu |
| CSI | Not enabled |
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Availability | SUNWxcu4 |
| CSI | Enabled |
| Interface Stability | Standard |
ed(1), sed(1), sh(1), tolower(3C), toupper(3C), ascii(5),
attributes(5), environ(5), largefile(5), standards(5)
Unlike some previous versions, /usr/xpg4/bin/tr correctly
processes NUL characters in its input stream. NUL characters
can be stripped by using tr -d '\000'.
Man(1) output converted with