JOIN(1) General Commands Manual JOIN(1)
join - relational database operator
join [ options ] file1 file2
Join forms, on the standard output, a join of the two relations speci-
fied by the lines of file1 and file2. If file1 is `-', the standard
input is used.
File1 and file2 must be sorted in increasing ASCII collating sequence
on the fields on which they are to be joined, normally the first in
There is one line in the output for each pair of lines in file1 and
file2 that have identical join fields. The output line normally con-
sists of the common field, then the rest of the line from file1, then
the rest of the line from file2.
Fields are normally separated by blank, tab or newline. In this case,
multiple separators count as one, and leading separators are discarded.
These options are recognized:
-an In addition to the normal output, produce a line for each
unpairable line in file n, where n is 1 or 2.
-e s Replace empty output fields by string s.
-jn m Join on the mth field of file n. If n is missing, use the mth
field in each file.
Each output line comprises the fields specifed in list, each
element of which has the form n.m, where n is a file number and
m is a field number.
-tc Use character c as a separator (tab character). Every appear-
ance of c in a line is significant.
sort(1), comm(1), awk(1)
With default field separation, the collating sequence is that of
sort -b; with -t, the sequence is that of a plain sort.
The conventions of join, sort, comm, uniq, look and awk(1) are wildly