UNIQ(1)                   BSD General Commands Manual                  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).

EXIT STATUS
     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
     A uniq command appeared in Version 3 AT&T UNIX.

BSD                            December 17, 2009                           BSD