join - relational database operator
join [-a file_number | -v file_number] [-e string] [-o list] [-t char] [-1 field] [-2 field] file1 file2
The join utility performs an ``equality join'' on the specified files and writes the result to the standard output. The ``join field'' is the field in each file by which the files are compared. The first field in each line is used by default. There is one line in the output for each pair of lines in file1 and file2 which have identical join fields. Each output line consists of the join field, the remaining fields from file1 and then the remaining fields from file2.
The defaults are: the join field is the first field in each line; fields in the input are separated by one or more blanks, with leading blanks on the line ignored; fields in the output are separated by a space; each output line consists of the join field, the remaining fields from file1, then the remaining fields from file2.
Many of the options use file and field numbers. Both file numbers and field numbers are 1 based, i.e. the first file on the command line is file number 1 and the first field is field number 1. The following options are available:
When the default field delimiter characters are used, the files to be joined should be ordered in the collating sequence of sort(1), using the -b option, on the fields on which they are to be joined, otherwise join may not report all field matches. When the field delimiter characters are specified by the -t option, the collating sequence should be the same as sort without the -b option.
If one of the arguments file1 or file2 is ``-'', the standard input is used.
The join utility exits 0 on success or >0 if an error occurred.
For compatibility with historic versions of join, the following options are available:
awk(1), comm(1), paste(1), sort(1), uniq(1)
join has no known bugs. It does not support the following historical switches: -a with no args. Patches are welcome.
The Perl implementation of join was written by Jonathan Feinberg, firstname.lastname@example.org.
This program is copyright (c) Jonathan Feinberg 1999.
This program is free and open software. You may use, modify, distribute, and sell this program (and any modified variants) in any way you wish, provided you do not restrict others from doing the same.