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TR(1)			  BSD General Commands Manual			 TR(1)

NAME
     tr — translate characters

SYNOPSIS
     tr [-Ccsu] string1 string2
     tr [-Ccu] -d string1
     tr [-Ccu] -s string1
     tr [-Ccu] -ds string1 string2

DESCRIPTION
     The tr utility copies the standard input to the standard output with sub‐
     stitution 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 trans‐
     lated 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 conven‐
		tions 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 char‐
		acter.

     c-c	For non-octal range endpoints represents the range of charac‐
		ters 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 end‐
		points, inclusive.

		See the COMPATIBILITY section below for an important note
		regarding differences in the way the current implementation
		interprets range expressions differently from previous imple‐
		mentations.

     [: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 char‐
		acters 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 tr as described in environ(7).

EXIT STATUS
     The tr utility exits 0 on success, and >0 if an error occurs.

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.

	   tr -cs "[:alpha:]" "\n" < file1

     Translate the contents of file1 to upper-case.

	   tr "[:lower:]" "[:upper:]" < file1

     (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.

	   tr -cd "[:print:]" < file1

     Remove diacritical marks from all accented variants of the letter ‘e’:

	   tr "[=e=]" "e"

COMPATIBILITY
     Previous FreeBSD implementations of tr 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 tr 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 dif‐
     fers.  As noted in the 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 ‘[’ char‐
     acter 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 com‐
     pression 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 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 syn‐
     tax.

STANDARDS
     The tr utility conforms to IEEE Std 1003.1-2001 (“POSIX.1”).  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 IEEE Std
     1003.1-2001 (“POSIX.1”) standard.

BSD			       October 13, 2006				   BSD
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