uniq(1p) - phpMan

UNIQ(1P)                   POSIX Programmer's Manual                  UNIQ(1P)

PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.
NAME
       uniq - report or filter out repeated lines in a file
SYNOPSIS
       uniq [-c|-d|-u][-f fields][-s char][input_file [output_file]]
DESCRIPTION
       The uniq utility shall read an input file comparing adjacent lines, and
       write  one  copy of each input line on the output.  The second and suc-
       ceeding copies of repeated adjacent input lines shall not be written.
       Repeated lines in the input shall not be detected if they are not adja-
       cent.
OPTIONS
       The  uniq  utility  shall  conform  to  the  Base Definitions volume of
       IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
       The following options shall be supported:
       -c     Precede each output line with a count of the number of times the
              line occurred in the input.
       -d     Suppress  the  writing  of  lines  that  are not repeated in the
              input.
       -f  fields
              Ignore the first fields fields on each  input  line  when  doing
              comparisons, where fields is a positive decimal integer. A field
              is the maximal string matched by the basic regular expression:

              [[:blank:]]*[^[:blank:]]*
       If the fields option-argument specifies more fields than appear  on  an
       input line, a null string shall be used for comparison.
       -s  chars
              Ignore  the first chars characters when doing comparisons, where
              chars shall be a positive decimal integer. If specified in  con-
              junction  with  the  -f option, the first chars characters after
              the first fields fields shall be ignored. If the  chars  option-
              argument specifies more characters than remain on an input line,
              a null string shall be used for comparison.
       -u     Suppress the writing of lines that are repeated in the input.

OPERANDS
       The following operands shall be supported:
       input_file
              A pathname of the input file. If the input_file operand  is  not
              specified, or if the input_file is '-', the standard input shall
              be used.
       output_file
              A pathname of the output file. If the output_file operand is not
              specified,  the  standard  output shall be used. The results are
              unspecified if the file named by output_file is the  file  named
              by input_file.

STDIN
       The standard input shall be used only if no input_file operand is spec-
       ified or if input_file is '-' . See the INPUT FILES section.
INPUT FILES
       The input file shall be a text file.
ENVIRONMENT VARIABLES
       The following environment variables shall affect the execution of uniq:
       LANG   Provide a default value for the  internationalization  variables
              that  are  unset  or  null.  (See the Base Definitions volume of
              IEEE Std 1003.1-2001, Section  8.2,  Internationalization  Vari-
              ables  for the precedence of internationalization variables used
              to determine the values of locale categories.)
       LC_ALL If set to a non-empty string value, override the values  of  all
              the other internationalization variables.
       LC_COLLATE
              Determine the locale for ordering rules.
       LC_CTYPE
              Determine  the  locale  for  the  interpretation of sequences of
              bytes of text data as characters (for  example,  single-byte  as
              opposed  to  multi-byte characters in arguments and input files)
              and which characters constitute a <blank> in the current locale.
       LC_MESSAGES
              Determine the locale that should be used to  affect  the  format
              and contents of diagnostic messages written to standard error.
       NLSPATH
              Determine the location of message catalogs for the processing of
              LC_MESSAGES .

ASYNCHRONOUS EVENTS
       Default.
STDOUT
       The standard output shall be used only if  no  output_file  operand  is
       specified. See the OUTPUT FILES section.
STDERR
       The standard error shall be used only for diagnostic messages.
OUTPUT FILES
       If  the  -c option is specified, the output file shall be empty or each
       line shall be of the form:

              "%d %s", <number of duplicates>, <line>
       otherwise, the output file shall be empty or each line shall be of  the
       form:

              "%s", <line>
EXTENDED DESCRIPTION
       None.
EXIT STATUS
       The following exit values shall be returned:
        0     The utility executed successfully.
       >0     An error occurred.

CONSEQUENCES OF ERRORS
       Default.
       The following sections are informative.
APPLICATION USAGE
       The  sort utility can be used to cause repeated lines to be adjacent in
       the input file.
EXAMPLES
       The following input file data (but flushed left) was used  for  a  test
       series on uniq:

              #01 foo0 bar0 foo1 bar1
              #02 bar0 foo1 bar1 foo1
              #03 foo0 bar0 foo1 bar1
              #04
              #05 foo0 bar0 foo1 bar1
              #06 foo0 bar0 foo1 bar1
              #07 bar0 foo1 bar1 foo0
       What  follows  is a series of test invocations of the uniq utility that
       use a mixture of uniq options against the input file data. These  tests
       verify  the meaning of adjacent.  The uniq utility views the input data
       as a sequence of strings delimited  by  '\n'  .  Accordingly,  for  the
       fieldsth  member  of  the  sequence, uniq interprets unique or repeated
       adjacent lines strictly relative to the fields+1th member.
        1. This first example tests the line counting option,  comparing  each
           line of the input file data starting from the second field:

           uniq -c -f 1 uniq_0I.t
               1 #01 foo0 bar0 foo1 bar1
               1 #02 bar0 foo1 bar1 foo0
               1 #03 foo0 bar0 foo1 bar1
               1 #04
               2 #05 foo0 bar0 foo1 bar1
               1 #07 bar0 foo1 bar1 foo0
       The  number '2', prefixing the fifth line of output, signifies that the
       uniq utility detected a pair of repeated lines. Given the  input  data,
       this  can  only  be  true when uniq is run using the -f 1 option (which
       shall cause uniq to ignore the first field on each input line).
        2. The second example tests the option to suppress unique lines,  com-
           paring  each  line  of the input file data starting from the second
           field:

           uniq -d -f 1 uniq_0I.t
           #05 foo0 bar0 foo1 bar1
        3. This test suppresses repeated lines, comparing  each  line  of  the
           input file data starting from the second field:

           uniq -u -f 1 uniq_0I.t
           #01 foo0 bar0 foo1 bar1
           #02 bar0 foo1 bar1 foo1
           #03 foo0 bar0 foo1 bar1
           #04
           #07 bar0 foo1 bar1 foo0
        4. This suppresses unique lines, comparing each line of the input file
           data starting from the third character:

           uniq -d -s 2 uniq_0I.t
       In the last example, the uniq utility found no input matching the above
       criteria.
RATIONALE
       Some  historical implementations have limited lines to be 1080 bytes in
       length, which does not meet the implied {LINE_MAX} limit.
FUTURE DIRECTIONS
       None.
SEE ALSO
       comm, sort
COPYRIGHT
       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
       event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard
       is  the  referee document. The original Standard can be obtained online
       at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group                  2003                             UNIQ(1P)