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       join - join lines of two files on a common field


       join [OPTION]... FILE1 FILE2


       For  each  pair of input lines with identical join fields, write a line
       to standard output.  The default join field is the first, delimited  by
       whitespace.   When FILE1 or FILE2 (not both) is -, read standard input.

       -a FILENUM
              print unpairable lines coming from file FILENUM,  where  FILENUM
              is 1 or 2, corresponding to FILE1 or FILE2

       -e EMPTY
              replace missing input fields with EMPTY

       -i, --ignore-case
              ignore differences in case when comparing fields

       -j FIELD
              equivalent to ‘-1 FIELD -2 FIELD’

       -o FORMAT
              obey FORMAT while constructing output line

       -t CHAR
              use CHAR as input and output field separator

       -v FILENUM
              like -a FILENUM, but suppress joined output lines

       -1 FIELD
              join on this FIELD of file 1

       -2 FIELD
              join on this FIELD of file 2

              check  that  the  input  is  correctly sorted, even if all input
              lines are pairable

              do not check that the input is correctly sorted

              treat the first line in each file as field headers,  print  them
              without trying to pair them

       --help display this help and exit

              output version information and exit

       Unless  -t  CHAR  is  given,  leading  blanks  separate  fields and are
       ignored, else fields are separated by  CHAR.   Any  FIELD  is  a  field
       number  counted from 1.  FORMAT is one or more comma or blank separated
       specifications, each being  ‘FILENUM.FIELD’  or  ‘0’.   Default  FORMAT
       outputs  the join field, the remaining fields from FILE1, the remaining
       fields from FILE2, all separated by CHAR.

       Important: FILE1 and FILE2 must be sorted on the  join  fields.   E.g.,
       use ‘ sort -k 1b,1 ’ if ‘join’ has no options, or use ‘ join -t ’’ ’ if
       ‘sort’ has no options.  Note, comparisons honor the rules specified  by
       ‘LC_COLLATE’.   If  the  input  is  not sorted and some lines cannot be
       joined, a warning message will be given.


       Written by Mike Haertel.


       Report join bugs to
       GNU coreutils home page: <>
       General help using GNU software: <>
       Report join translation bugs to <>


       Copyright © 2010 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.


       comm(1), uniq(1)

       The full documentation for join is maintained as a Texinfo manual.   If
       the  info  and  join  programs are properly installed at your site, the

              info coreutils 'join invocation'

       should give you access to the complete manual.