NAME

join − relational database operator

SYNOPSIS

join [ options ] file1 file2

DESCRIPTION

Join forms, on the standard output, a join of the two relations 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, normally 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 new-line.  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 specified 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 appearance of c in a line is significant. 

EXAMPLE

If "file1" contains: Austen -
Bailey -
Clark -
Dawson -
Smith -

and "file2" contains: Austen Jack Anchor Brewery
Clark Maryann Shoeshop
Daniels Steve Computer Software
Dawson Sylvia Toot Sweets
Smith Sally Talcum Powdery

then

join −j1 1  −j2 1  −o 2.2 2.1 1.2 2.3 2.4 file1 file2

will generate

Jack Austen - Anchor Brewery
Maryann Clark - Shoeshop
Sylvia Dawson - Toot Sweets
Sally Smith - Talcum Powdery

SEE ALSO

awk(1), comm(1), sort(1). 

BUGS

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 and awk(1) are wildly incongruous.

Version 2.3  —  July 04, 1985