Unix in a Nutshell, 4th Edition

Name

join

Synopsis

    join [options]file1 file2

Join the common lines of sorted file1 and sorted file2. Read standard input if file1 is -. The output contains the common field and the remainder of each line from file1 and file2. In the options below, n can be 1 or 2, referring to file1 or file2.

Common Options

-a filenum

List unpairable lines in file filenum. Use -a 1 -a 2 to list unpairable lines from both files.

-e string

Replace any empty output field with the string string.

-o n.m

Each output line contains fields specified by file number n and field number m. The common field is suppressed unless requested.

-t c

Use character c as field separator for input and output.

-v n

Print only the unpairable lines in file n. With both -v 1 and -v 2, all unpairable lines are printed.

-1 m

Join on field m of file 1. Fields start with 1.

-2 m

Join on field m of file 2. Fields start with 1.

Solaris and GNU/Linux Option

-j fieldnum

Equivalent to -1 fieldnum -2 fieldnum.

Solaris Options

-j1 fieldnum

Equivalent to -1 fieldnum.

-j2 fieldnum

Equivalent to -2 fieldnum.

GNU/Linux Option

-i, --ignore-case

Ignore case differences when comparing keys.

Examples

Assuming the following input files:

    $ cat score
    olga    81      91
    rene    82      92
    zack    83      93
    $ cat grade
    olga    B       A
    rene    B       A

List scores followed by grades, including unmatched lines:

    $ join -a1 score grade
    olga 81 91 B A
    rene 82 92 B A
    zack 83 93

Pair each score with its grade:

    $ join -o 1.1 1.2 2.2 1.3 2.3 score grade
    olga 81 B 91 A
    rene 82 B 92 A