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
replace missing input fields with EMPTY
ignore differences in case when comparing fields
equivalent to `-1 FIELD -2 FIELD'
obey FORMAT while constructing output line
use CHAR as input and output field separator
like -a FILENUM, but suppress joined output lines
join on this FIELD of file 1
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
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,
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.