join - relational database operator

join performs an equality join on the files file1 and file2 and writes the resulting joined files to standard output. By default, a field is delimited by one or more spaces and tabs with leading spaces and/or tabs ignored. The -t option can be used to change the field delimiter.

The join field is a field in each file on which files are compared. By default join writes one line in the output for each pair of lines in files1 and files2 that have identical join fields. The default output line consists of the join field, then the remaining fields from file1, then the remaining fields from file2, but this can be changed with the -o option. The -a option can be used to add unmatched lines to the output. The -v option can be used to output only unmatched lines.

The files file1 and file2 must be ordered in the collating sequence of sort -b on the fields on which they are to be joined otherwise the results are unspecified.

If either file1 or file2 is -, join uses standard input starting at the current location.

-e, --empty=string

Replace empty output fields in the list selected with -o with string.

-o, --output=list

Construct the output line to comprise the fields specified in a blank or comma separated list list. Each element in list consists of a file number (either 1 or 2), a period, and a field number or 0 representing the join field. As an obsolete feature multiple occurrences of -o can be specified.

-t, --separator|tabs=delim

Use delim as the field separator for both input and output.

-1, --j1=field

Join on field field of file1. Fields start at 1.

-2, --j2=field

Join on field field of file2. Fields start at 1.

-j, --join=field

Equivalent to -1 field -2 field.

-a, --unpairable=fileno

Write a line for each unpairable line in file fileno, where fileno is either 1 or 2, in addition to the normal output. If -a options appear for both 1 and 2, then all unpairable lines will be output.

-v, --suppress=fileno

Write a line for each unpairable line in file fileno, where fileno is either 1 or 2, instead of the normal output. If -v options appear for both 1 and 2, then all unpairable lines will be output.

-i, --ignorecase

Ignore case in field comparisons.

-B, --mmap

Enable memory mapped reads instead of buffered. On by default; -B means --nommap.

The following obsolete option forms are also recognized: -j field is equivalent to -1 field -2 field, -j1 field is equivalent to -1 field, and -j2 field is equivalent to -2 field.

0

Both files processed successfully.

>0

An error occurred.

cut(1), comm(1), paste(1), sort(1), uniq(1)

version

join (AT&T Research) 2009-12-10

author

Glenn Fowler <gsf@research.att.com>

author

David Korn <dgk@research.att.com>

copyright

Copyright © 1992-2012 AT&T Intellectual Property

license

http://www.eclipse.org/org/documents/epl-v10.html