TR(1) User Commands TR(1)


NAME


tr - translate characters

SYNOPSIS


/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


DESCRIPTION


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.

OPTIONS


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.

OPERANDS


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.


/usr/xpg4/bin/tr
c-c


/usr/bin/tr
[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 thestring2-based sequence to the
length of the string1-based sequence.


USAGE


See largefile(5) for the description of the behavior of tr when
encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).

EXAMPLES


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 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


ENVIRONMENT VARIABLES


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.

EXIT STATUS


The following exit values are returned:

0
All input was processed successfully.


>0
An error occurred.


ATTRIBUTES


See attributes(5) for descriptions of the following attributes:

/usr/bin/tr

+---------------+-----------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-----------------+
|CSI | Enabled |
+---------------+-----------------+

/usr/xpg4/bin/tr

+--------------------+-------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------+
|CSI | Enabled |
+--------------------+-------------------+
|Interface Stability | Committed |
+--------------------+-------------------+
|Standard | See standards(5). |
+--------------------+-------------------+

/usr/xpg6/bin/tr

+--------------------+-------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------+
|CSI | Enabled |
+--------------------+-------------------+
|Interface Stability | Committed |
+--------------------+-------------------+
|Standard | See standards(5). |
+--------------------+-------------------+

SEE ALSO


ed(1), sed(1), sh(1), tolower(3C), toupper(3C), ascii(5), attributes(5),
environ(5), largefile(5), regex(5), standards(5)

NOTES


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'.


March 3, 2009 TR(1)