tr - translate characters
/usr/bin/tr [-cds] [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
/usr/xpg6/bin/tr [-c | -C] [-s] string1 string2
/usr/xpg6/bin/tr -s [-c | -C] string1
/usr/xpg6/bin/tr -d [-c | -C] string1
/usr/xpg6/bin/tr -ds [-c | -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 values specified by
string1.
-C
Complements the set of characters specified by
string1.
-d
Deletes all occurrences of input characters that are
specified by string1.
-s
Replaces instances of repeated characters with a single
character.
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 relative position in the array
specified by string2. When the array specified by string2 is
shorter than the one specified by string1, the results are
unspecified.
- o
- If the -c option is specified, the complements of the values
specified by string1 are placed in the array in ascending order by
binary value.
- o
- If the -C option is specified, the complements of the characters
specified by string1 (the set of all characters 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 described previously.
When the -d option is specified:
- o
- Input characters found in the array specified by string1 are
deleted.
- o
- When the -C option is specified with -d, all values except
those specified by string1 are deleted. The contents of
string2 are ignored, unless the -s option is also
specified.
- o
- If the -c option is specified, the complements of the values
specified by string1 are placed in the array in ascending order by
binary value.
- 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 is
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 contains 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 contains only those characters defined as
the second characters in each of the toupper or tolower
character pairs, as appropriate. (See toupper(3C) and
tolower(3C)).
An empty string used for string1 or string2 produces
undefined results.
The following operands are supported:
string1
string2
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 collating elements. If any of
the constructs result in multi-character collating elements, tr
excludes, without a diagnostic, those multi-character elements from the
resulting array.
character
Any character not described by one of the conventions
below represents itself.
\octal
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.
\character
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]
In the POSIX locale, this construct represents the range
of collating elements between the range endpoints (as long as neither endpoint
is an octal sequence of the form
\octal), inclusively, as
defined by the collation sequence. The characters or collating elements in the
range are placed in the array in ascending collation sequence. If the second
endpoint precedes the starting endpoint in the collation sequence, it is
unspecified whether the range of collating elements is empty, or this
construct is treated as invalid. In locales other than the POSIX locale, this
construct has unspecified behavior.
If either or both of the range endpoints are octal sequences of
the form \octal, represents the range of specific coded binary
values between two range endpoints, inclusively.
[:class:]
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 are accepted when
specified in
string1:
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.
When both the -d and -s options are specified, any
of the character class names are accepted in string2. Otherwise, only
character class names lower or upper are valid in
string2 and then only if the corresponding 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
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 contain the characters from the tolower mapping in the
LC_CTYPE category of the current locale. The first character from
each mapping pair is in the array for string1 and the second
character from each mapping pair is 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.
[=equiv=]
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 characters to one,
it is only valid when it occurs in
string2. If
n has a leading
0, it is interpreted as an octal value. Otherwise, it is interpreted as
a decimal value.
If n is omitted or is 0, /usr/bin/tr
interprets this as huge; /usr/xpg4/bin/tr and /usr/xpg6/bin/tr
interprets this as large enough to extend the string2-based sequence
to the length of the string1-based sequence.
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 example 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 accomplished (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(7) 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(7) for descriptions of the following attributes:
| ATTRIBUTE
TYPE |
ATTRIBUTE VALUE |
| CSI |
Enabled |
| ATTRIBUTE
TYPE |
ATTRIBUTE VALUE |
| CSI |
Enabled |
| Interface Stability |
Committed |
| Standard |
See standards(7). |
| ATTRIBUTE
TYPE |
ATTRIBUTE VALUE |
| CSI |
Enabled |
| Interface Stability |
Committed |
| Standard |
See standards(7). |
ed(1), sed(1), sh(1), tolower(3C),
toupper(3C), ascii(7), attributes(7), environ(7),
largefile(7), regex(7), standards(7)
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'.