uniq
GPLv3+ Plan 9: MIT License | |
|---|---|
| Website | man7 |
uniq is a utility command on Unix, Plan 9, Inferno, and Unix-like operating systems which, when fed a text file or standard input, outputs the text with adjacent identical lines collapsed to one, unique line of text.
Overview
The command is a kind of
filter program. Typically it is used after
. It can also output only the duplicate lines (with the sort-d option), or add the number of occurrences of each line (with the -c option). For example, the following command lists the unique lines in a file, sorted by the number of times each occurs:
$ sort file | uniq -c | sort -n
Using uniq like this is common when building pipelines in shell scripts.
History
First appearing in
Single Unix Specification.[2]
The version bundled in
coreutils was written by Richard Stallman and David MacKenzie.[3]
A uniq command is also part of ASCII's MSX-DOS2 Tools for MSX-DOS version 2.[4]
The command is available as a separate package for Microsoft Windows as part of the GnuWin32 project[5] and the UnxUtils collection of native Win32 ports of common GNU Unix-like utilities.[6]
The uniq command has also been ported to the IBM i operating system.[7]
See also
- List of Unix commands
References
- McIlroy, M. D. (1987). A Research Unix reader: annotated excerpts from the Programmer's Manual, 1971–1986(PDF) (Technical report). CSTR. Bell Labs. 139.
- The Single UNIX Specification, Version 4 from The Open Group
- ^ – Linux General Commands Manual
- ^ MSX-DOS2 Tools User's Manual by ASCII Corporation
- ^ CoreUtils for Windows
- ^ Native Win32 ports of some GNU utilities
- ^ IBM. "IBM System i Version 7.2 Programming Qshell" (PDF). IBM. Retrieved 2020-09-05.
External links
The Wikibook Guide to Unix has a page on the topic of: Commands
- – Linux User Manual – User Commands
- – Plan 9 Programmer's Manual, Volume 1
- – Inferno General commands Manual
- SourceForge UnxUtils – Port of several GNU utilities to Windows
| File system | |
|---|---|
| Processes | |
| User environment | |
| Text processing | |
| Shell builtins | |
| Searching | |
| Documentation | |
| Software development | |
| Miscellaneous | |
| |
| File system | |
|---|---|
| Processes | |
| User environment | |
| Text processing | |
| Shell builtins | |
| Networking | |
| Searching | |
| Software development | |
| Miscellaneous | |