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.
 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’
 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
--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. 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: <>


Copyright © 2009 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.


The full documentation for join is maintained as a Texinfo manual. If the info and join programs are properly installed at your site, the command
info coreutils 'join invocation'
should give you access to the complete manual.

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