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
       ignored,  else fields are separated by CHAR.  Any FIELD is a field
       number counted from 1.  FORMAT is one or more comma or blank sepa‐
       rated  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.

AUTHOR
       Written by Mike Haertel.

REPORTING BUGS
       GNU  coreutils  online  help:  <https://www.gnu.org/software/core‐
       utils/>
       Report   any   translation   bugs   to    <https://translationpro‐
       ject.org/team/>

COPYRIGHT
       Copyright  ©  2020 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 <https://www.gnu.org/software/coreutils/join>
       or available locally via: info '(coreutils) join invocation'

GNU coreutils 8.32              April 2020                        JOIN(1)