UNIQ(1)                     General Commands Manual                    UNIQ(1)


     uniq - report or filter out repeated lines in a file


     uniq [-ci] [-d | -u] [-f fields] [-s chars] [input_file [output_file]]


     The uniq utility reads the standard input comparing adjacent lines and
     writes a copy of each unique input line to the standard 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 options are as follows:

     -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 which have duplicates.

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

     -i      Regard lower and upper case ASCII characters as identical.

     -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 fields fields will be
             ignored.  Character numbers are one based, i.e., the first
             character is character one.

     -u      Only output lines which are unique.

     If additional arguments are specified on the command line, the first such
     argument is used as the name of an input file, the second is used as the
     name of an output file.  A file name of `-' denotes the standard input or
     the standard output (depending on its position on the command line).


     LC_CTYPE  The character encoding locale(1).  It decides which byte
               sequences form characters and which characters are considered
               blank.  If unset or set to "C", "POSIX", or an unsupported
               value, each byte is treated as a character, and only space and
               tab are considered blank.

               This variable is ignored for case comparisons.  Lower and upper
               case versions of non-ASCII characters are always considered


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




     The uniq utility is compliant with the IEEE Std 1003.1-2008 ("POSIX.1")

     The -i option and the use of -c in conjunction with -d or -u are
     extensions to that specification.

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

OpenBSD 6.4                    December 23, 2017                   OpenBSD 6.4

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