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uniq(1)

NAME

     uniq -- report or filter out repeated lines in a file

SYNOPSIS

     uniq [-c | -d | -u] [-i] [-f num] [-s chars] [input_file [output_file]]

DESCRIPTION

     The uniq utility reads the specified input_file comparing adjacent lines,
     and writes a copy of each unique input line to the output_file.  If
     input_file is a single dash (`-') or absent, the standard input is read.
     If output_file is absent, standard output is used for output.  The second
     and succeeding copies of identical adjacent input lines are not written.
     Repeated lines in the input will not be detected if they are not adja-
     cent, so it may be necessary to sort the files first.

     The following options are available:

     -c      Precede each output line with the count of the number of times
	     the line occurred in the input, followed by a single space.

     -d      Only output lines that are repeated in the input.

     -f num  Ignore the first num fields in each input line when doing compar-
	     isons.  A field is a string of non-blank characters separated
	     from adjacent fields by blanks.  Field numbers are one based,
	     i.e., the first field is field one.

     -s chars
	     Ignore the first chars characters in each input line when doing
	     comparisons.  If specified in conjunction with the -f option, the
	     first chars characters after the first num fields will be
	     ignored.  Character numbers are one based, i.e., the first char-
	     acter is character one.

     -u      Only output lines that are not repeated in the input.

     -i      Case insensitive comparison of lines.

ENVIRONMENT

     The LANG, LC_ALL, LC_COLLATE and LC_CTYPE environment variables affect
     the execution of uniq as described in environ(7).

DIAGNOSTICS

     The uniq utility exits 0 on success, and >0 if an error occurs.

COMPATIBILITY

     The historic +number and -number options have been deprecated but are
     still supported in this implementation.

SEE ALSO

     sort(1)

STANDARDS

     The uniq utility conforms to IEEE Std 1003.1-2001 (``POSIX.1'') as
     amended by Cor. 1-2002.

HISTORY

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