Linux "join" Command Line Options and Examples
join lines of two files on a common field
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.
join [OPTION]... FILE1 FILE2
Command Line Options:
also print unpairable lines from file FILENUM, where FILENUM is 1 or 2, corresponding to FILE1 or FILE2
join -a ...
replace missing input fields with EMPTY
join -e ...
ignore differences in case when comparing fields
join -i ...
equivalent to '-1 FIELD -2 FIELD'
join -j ...
obey FORMAT while constructing output line
join -o ...
use CHAR as input and output field separator
join -t ...
like -a FILENUM, but suppress joined output lines
join -v ...
join on this FIELD of file 1
join -1 ...
join on this FIELD of file 2
join -2 ...
check that the input is correctly sorted, even if all input lines are pairable
join --check-order ...
do not check that the input is correctly sorted
join --nocheck-order ...
treat the first line in each file as field headers, print them without trying to pair them
join --header ...
line delimiter is NUL, not newline
join -z ...
display this help and exit
join --help ...
output version information and exitUnless -t CHAR is given, leading blanks separate fields and are ignored, else fields are separated by CHAR. Any FIELD is a fieldnumber counted from 1. FORMAT is one or more comma or blank separated specifications, each being 'FILENUM.FIELD' or '0'. DefaultFORMAT outputs the join field, the remaining fields from FILE1, the remaining fields from FILE2, all separated by CHAR. If FORMAT isthe 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 linescannot be joined, a warning message will be given.AUTHORWritten by Mike Haertel.REPORTING BUGSGNU coreutils online help: <http://www.gnu.org/software/coreutils/>Report join translation bugs to <http://translationproject.org/team/>COPYRIGHTCopyright © 2017 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://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.
join --version ...