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FreeBSD man pages : uniq (1)
UNIQ(1) 		FreeBSD General Commands Manual 	       UNIQ(1)


uniq - report or filter out repeated lines in a file


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


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 charac- ter is character one. -u Only output lines that are not repeated in the input. -i Case insensitive comparison of lines. If additional arguments are specified on the command line, the first argument is used as the name of an input file, the second is used as the name of an output file.


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


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




The uniq utility is expected to be IEEE Std 1003.2 (``POSIX.2'') compati- ble.


A uniq command appeared in Version 3 AT&T UNIX. FreeBSD 4.8 June 6, 1993 FreeBSD 4.8