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uniq(1) [centos man page]

UNIQ(1) 							   User Commands							   UNIQ(1)

uniq - report or omit repeated lines SYNOPSIS
Filter adjacent matching lines from INPUT (or standard input), writing to OUTPUT (or standard output). With no options, matching lines are merged to the first occurrence. Mandatory arguments to long options are mandatory for short options too. -c, --count prefix lines by the number of occurrences -d, --repeated only print duplicate lines, one for each group -D, --all-repeated[=METHOD] print all duplicate lines groups can be delimited with an empty line METHOD={none(default),prepend,separate} -f, --skip-fields=N avoid comparing the first N fields --group[=METHOD] show all items, separating groups with an empty line METHOD={separate(default),prepend,append,both} -i, --ignore-case ignore differences in case when comparing -s, --skip-chars=N avoid comparing the first N characters -u, --unique only print unique lines -z, --zero-terminated end lines with 0 byte, not newline -w, --check-chars=N compare no more than N characters in lines --help display this help and exit --version output version information and exit A field is a run of blanks (usually spaces and/or TABs), then non-blank characters. Fields are skipped before chars. Note: 'uniq' does not detect repeated lines unless they are adjacent. You may want to sort the input first, or use 'sort -u' without 'uniq'. Also, comparisons honor the rules specified by 'LC_COLLATE'. GNU coreutils online help: <> Report uniq translation bugs to <> AUTHOR
Written by Richard M. Stallman and David MacKenzie. COPYRIGHT
Copyright (C) 2013 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO
comm(1), join(1), sort(1) The full documentation for uniq is maintained as a Texinfo manual. If the info and uniq programs are properly installed at your site, the command info coreutils 'uniq invocation' should give you access to the complete manual. GNU coreutils 8.22 June 2014 UNIQ(1)

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UNIQ(1) 						    BSD General Commands Manual 						   UNIQ(1)

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 adjacent, 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 comparisons. 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 character 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
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
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