JOIN(1) JOIN(1)
NAME
join - relational database operator
SYNOPSIS
join [ options ] file1 file2
DESCRIPTION
Join forms, on the standard output, a join of the two rela-
tions specified 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, nor-
mally the first in each line.
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 consists 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.
-o list
Each output line comprises the fields specifed in list,
each element of which is 0 or has the form n.m, where n
is a file number and m is a field number. 0 designates
the join field.
-tc Use character c as a separator (tab character). Every
appearance of c in a line is significant.
SEE ALSO
sort(1), comm(1), awk(1)
BUGS
With default field separation, the collating sequence is
that of sort -b; with -t, the sequence is that of a plain
JOIN(1) JOIN(1)
sort.
The conventions of join, sort, comm, uniq, look and awk(1)
are wildly incongruent.