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

   When FILE1 or FILE2 (not both) is -, read standard input.

          also  print unpairable lines 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

          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

   -z, --zero-terminated
          line delimiter is NUL, not newline

   --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.  If FORMAT is the keyword
   'auto', then the first line of  each  file  determines  the  number  of
   fields output for each line.

   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.


   GNU coreutils online help: <>
   Report join translation bugs to <>


   Copyright    2016  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)

   Full documentation at: <>
   or available locally via: info '(coreutils) join invocation'


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