The
utility copies the standard input to the standard output with substitution
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 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 translated 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 conventions
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<alert character>
"\b<backspace>
"\f<form-feed>
"\n<newline>
"\r<carriage return>
"\t<tab>
"\v<vertical tab>
A backslash followed by any other character maps to that character.
c-c
For non-octal range endpoints
represents the range of characters between the range endpoints, inclusive,
in ascending order,
as defined by the collation sequence.
If either or both of the range endpoints are octal sequences, it
represents the range of specific coded values between the
range endpoints, inclusive.
Bf Em
See the
Sx COMPATIBILITY
section below for an important note regarding
differences in the way the current
implementation interprets range expressions differently from
previous implementations.
Ef
[:class:]
Represents all characters belonging to the defined character class.
Class names are:
"alnum<alphanumeric characters>
"alpha<alphabetic characters>
"blank<whitespace characters>
"cntrl<control characters>
"digit<numeric characters>
"graph<graphic characters>
"ideogram<ideographic characters>
"lower<lower-case alphabetic characters>
"phonogram<phonographic characters>
"print<printable characters>
"punct<punctuation characters>
"rune<valid characters>
"space<space characters>
"special<special characters>
"upper<upper-case characters>
"xdigit<hexadecimal characters>
When
``[:lower:]
''
appears in
string1
and
``[:upper:]
''
appears in the same relative position in
string2
it represents the characters pairs from the
toupper
mapping in the
LC_CTYPE
category of the current locale.
When
``[:upper:]
''
appears in
string1
and
``[:lower:]
''
appears in the same relative position in
string2
it represents the characters pairs from the
tolower
mapping in the
LC_CTYPE
category of the current locale.
With the exception of case conversion,
characters in the classes are in unspecified order.
For specific information as to which
ASCII
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 is interpreted as a decimal value.
ENVIRONMENT
The
LANG , LC_ALL , LC_CTYPE
and
LC_COLLATE
environment variables affect the execution of
as described in
environ(7).
EXIT STATUS
Ex -std
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.
Translate the contents of file1 to upper-case.
(This should be preferred over the traditional
UNIX
idiom of
``tr a-z A-Z
''
since it works correctly in all locales.)
Strip out non-printable characters from file1.
Remove diacritical marks from all accented variants of the letter
`e'
:
"tr [=e=] e"
COMPATIBILITY
Previous
Fx implementations of
did not order characters in range expressions according to the current
locale's collation order, making it possible to convert unaccented Latin
characters (esp. as found in English text) from upper to lower case using
the traditional
UNIX
idiom of
``tr A-Z a-z
''
Since
now obeys the locale's collation order, this idiom may not produce
correct results when there is not a 1:1 mapping between lower and
upper case, or when the order of characters within the two cases differs.
As noted in the
Sx EXAMPLES
section above, the character class expressions
``[:lower:]
''
and
``[:upper:]
''
should be used instead of explicit character ranges like
``a-z
''
and
``A-Z
''
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 deletion or compression list which would not have happened
under a 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
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
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 syntax.
STANDARDS
The
utility conforms to
St -p1003.1-2001 .
The
``ideogram''
``phonogram''
``rune''
and
``special''
character classes are extensions.
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
St -p1003.1-2001
standard.
