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NetBSD 6.1.5 - man page for tr (netbsd section 1)

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

NAME
     tr -- translate characters

SYNOPSIS
     tr [-cs] string1 string2
     tr [-c] -d string1
     tr [-c] -s string1
     tr [-c] -ds string1 string2

DESCRIPTION
     The tr utility copies the standard input to the standard output with substitution or dele-
     tion of selected characters.

     The following options are available:

     -c      Complements the set of characters in string1, that is -c ab includes every character
	     except for 'a' and 'b'.

     -d      The -d option causes characters to be deleted from the input.

     -s      The -s option squeezes multiple occurrences of the characters listed in the last op-
	     erand (either string1 or string2) in the input into a single instance of the charac-
	     ter.  This occurs after all deletion and translation is completed.

     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	Represents the range of characters between the range endpoints, inclusively.

     [:class:]	Represents all characters belonging to the defined character class.  Class names
		are:

		alnum	  <alphanumeric characters>
		alpha	  <alphabetic characters>
		blank	  <blank characters>
		cntrl	  <control characters>
		digit	  <numeric characters>
		graph	  <graphic characters>
		lower	  <lower-case alphabetic characters>
		print	  <printable characters>
		punct	  <punctuation characters>
		space	  <space characters>
		upper	  <upper-case characters>
		xdigit	  <hexadecimal characters>

		With the exception of the ``upper'' and ``lower'' classes, characters in the
		classes are in unspecified order.  In the ``upper'' and ``lower'' classes, char-
		acters are entered in ascending 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 or collating (sorting) elements belonging to the same
		equivalence class as equiv.  If there is a secondary ordering within the equiva-
		lence class, the characters are ordered in ascending sequence.	Otherwise, they
		are ordered after their encoded values.  An example of an equivalence class might
		be ``c'' and ``ch'' in Spanish; English has no equivalence classes.

     [#*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 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, other-
		wise, it's interpreted as a decimal value.

EXIT STATUS
     tr 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

     Strip out non-printable characters from file1:

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

COMPATIBILITY
     AT&T System V UNIX has historically implemented character ranges using the syntax ``[c-c]''
     instead of the ``c-c'' used by historic BSD implementations and standardized by POSIX.  AT&T
     System V UNIX 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.  How-
     ever, 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 an historic AT&T System V UNIX 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 syntax.

STANDARDS
     The tr utility is expected to be IEEE Std 1003.2 (``POSIX.2'') compatible.  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.

BUGS
     tr was originally designed to work with US-ASCII.	Its use with character sets that do not
     share all the properties of US-ASCII, e.g., a symmetric set of upper and lower case charac-
     ters that can be algorithmically converted one to the other, may yield unpredictable
     results.

     tr should be internationalized.

BSD					  March 23, 2004				      BSD


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