join

JOIN(1)                          User Commands                         JOIN(1)

NAME
       join - join lines of two files on a common field

SYNOPSIS
       join [OPTION]... FILE1 FILE2

DESCRIPTION
       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
       blanks.

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

       -a FILENUM
              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

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

       --nocheck-order
              do not check that the input is correctly sorted

       --header
              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

       --version
              output version information and exit

       Unless -t CHAR is given, leading blanks separate  fields  and  are  ig-
       nored,  else fields are separated by CHAR.  Any FIELD is a field number
       counted from 1.  FORMAT is one or more comma or blank separated  speci-
       fications,  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.

AUTHOR
       Written by Mike Haertel.

REPORTING BUGS
       GNU coreutils online help: <https://www.gnu.org/software/coreutils/>
       Report join translation bugs to <https://translationproject.org/team/>

COPYRIGHT
       Copyright  (C) 2018 Free Software Foundation, Inc.  License GPLv3+: GNU
       GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
       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), uniq(1)

       Full documentation at: <https://www.gnu.org/software/coreutils/join>
       or available locally via: info '(coreutils) join invocation'

GNU coreutils 8.30              September 2019                         JOIN(1)