Editing GNU Screen

{{Short description|Terminal multiplexer software}}
{{Infobox software
| name                   = GNU Screen
| logo                   = Heckert GNU white.svg
| screenshot             = gnuscreen.png
| caption                = GNU Screen with split-screen
| author                 = Oliver Laumann, Carsten Bormann
| developer              = Amadeusz Sławiński, Alexander Naumov and the [[GNU Project]]
| released               = {{Start date and age|1987}}
| latest release version = {{wikidata|property|preferred|references|edit|Q930835|P348|P548=Q2804309}}
| latest release date    = {{wikidata|qualifier|preferred|single|Q930835|P348|P548=Q2804309|P577}}
| latest preview version = {{wikidata|property|preferred|references|edit|Q930835|P348|P548=Q51930650}}
| latest preview date    = {{wikidata|qualifier|preferred|single|Q930835|P348|P548=Q51930650|P577}}
| programming language   = [[C (programming language)|C]]
| operating system       = [[Unix-like]]
| language               = 
| genre                  = [[Terminal multiplexer]]
| license                = [[GNU General Public License|GPL-3.0-or-later]]
| website                = {{URL|https://www.gnu.org/software/screen/}}
}}

'''GNU Screen''' is a [[terminal multiplexer]]: a [[software application]] that can be used to [[multiplexing|multiplex]] several [[virtual console]]s, allowing a user to access multiple separate [[login session]]s inside a single [[computer terminal|terminal]] window, or detach and reattach sessions from a terminal. It is useful for dealing with multiple programs from a [[command line interface]], and for separating programs from the session of the [[Unix shell]] that started the program, particularly so a remote [[process (computing)|process]] continues running even when the user is disconnected.

Released under the terms of version 3 or later of the [[GNU General Public License]], GNU Screen is [[free software]].

==Features==
{{Further|Terminal multiplexer}}

GNU Screen can be thought of as a [[Text mode|text version]] of graphical [[window manager]]s, or as a way of putting virtual terminals into any login session. It is a wrapper that allows multiple text programs to run at the same time, and provides features that allow the user to use the programs within a single interface productively. This enables the [[Terminal multiplexer#Features|following features]]: persistence, multiple windows, and session sharing.

Screen is often used when a network connection to the terminal is unreliable, as a dropped network connection typically terminates all programs the user was running (child processes of the login session), due to the session ending and sending a "hangup" signal ([[SIGHUP]]) to all the child processes. Running the applications under screen means that the session does not terminate – only the now-defunct terminal gets detached – so applications don't even know the terminal has detached, and allows the user to reattach the session later and continue working from where they left off.

[[File:Screen-manager-screen-in-peropesis-linux.webm|thumb|Example of working with the GNU Screen]]
==History==
Screen was originally designed by Oliver Laumann and Carsten Bormann at [[Technische Universität Berlin]] and published in 1987.<ref>{{cite newsgroup|newsgroup= net.sources |title= BSD screen manager -- Part 1 of 2 - (nf)|url= https://groups.google.com/d/msg/net.sources/5V9QWdIynTY/nrJLMWpznEUJ|date= 20 Mar 1987|access-date= 15 May 2017}}</ref><ref>{{cite newsgroup|newsgroup= net.sources |title= BSD screen manager -- Part 2 of 2 - (nf)|url= https://groups.google.com/d/msg/net.sources/yxL7-hyAgQ4/eKbx3tOcrVwJ|date= 20 Mar 1987|access-date= 15 May 2017}}</ref>

Design criteria included [[VT100]] emulation (including ANSI X3.64 (ISO 6429) and ISO 2022) and reasonable performance for heavy daily use when [[character-based terminals]] were still common. Later, the at-the-time novel feature of disconnection/reattachment was added.

Around 1990, Laumann handed over maintenance of the code to Jürgen Weigert and Michael Schroeder at the [[University of Erlangen–Nuremberg]], who later moved the project to the [[GNU Project]] and added features such as scrollback, split-screen, [[copy-and-paste]], and [[screen sharing]].<ref name="screen_ftp">[http://ftp.gnu.org/gnu/screen/ screen ftp]</ref>

By 2014, development had slowed to a crawl. Wanting to change this, Amadeusz Sławiński volunteered to help. In response, Laumann granted him maintainership. Sławiński proceeded to put out the first new Screen release in half a decade. Because there were some unofficial "Screen 4.1" releases floating around the Internet, he called this new release "Screen 4.2.0".

In May 2015, on openSUSE Conference, Jürgen Weigert invited Alexander Naumov to help to develop and maintain GNU screen. Two months later with Alex's help ''[https://savannah.gnu.org/forum/forum.php?forum_id=8293 GNU screen 4.3.0]'' was released.

==See also==
{{Portal|Free and open-source software}}
* [[xpra]], a tool to run [[X Window System]] applications on one machine, disconnect them from that machine's display, then reconnect them to another machine's display.
* [[Byobu (software)|Byobu]], a frontend for GNU Screen or tmux
* [[tmux]], an [[ISC License|ISC-licensed]] terminal multiplexer with a feature set similar to GNU Screen

==Further reading==
* Jeff Covey (12 Oct 2002) ''[http://freshmeat.sourceforge.net/articles/the-antidesktop The Antidesktop]'', [[Freshmeat]]

==References==
{{Refbegin}}
* Martin Streicher (10 Feb 2009) ''[https://developer.ibm.com/articles/au-gnu_screen/ Speaking UNIX: Stayin' alive with Screen]'', IBM DeveloperWorks
* Philip J. Hollenback (22 Aug 2006) ''[https://www.linux.com/tutorials/using-screen-remote-interaction/ Using screen for remote interaction]'', [[Linux.com]]
* Adam Lazur (January 2003) ''[https://www.linuxjournal.com/article/6340 Power Sessions with Screen]'', [[Linux Journal]], issue 105
* William Von Hagen, Brian K. Jones, ''Linux server hacks, Volume 2'', O'Reilly Media, 2005, {{ISBN|0-596-10082-5}}, pp.&nbsp;155&ndash;157 (Hack #34)
* Carl Albing, J. P. Vossen, Cameron Newham, ''Bash cookbook'', O'Reilly Media, 2007, {{ISBN|0-596-52678-4}}, pp.&nbsp;415&ndash;418
* Dru Lavigne, ''BSD hacks'', O'Reilly Media, 2004, {{ISBN|0-596-00679-9}}, pp.&nbsp;44&ndash;48 (Hack #12)<!-- this is about screen not tmux (old BSD book) -->
* Noah Gift, Jeremy Jones, ''Python for Unix and Linux system administration'', O'Reilly Germany<!-- the book is in English-->, 2008, {{ISBN|0-596-51582-0}}, pp.&nbsp;300&ndash;301
* Paul Mutton, ''IRC hacks'', O'Reilly Media, 2004, {{ISBN|0-596-00687-X}}, pp.&nbsp;345&ndash;349 (Hack #92)
{{Refend}}

===Notes===
{{Reflist}}

==External links==
* {{Official website}}
* [http://aperiodic.net/screen/quick_reference Quick reference]
* [https://savannah.gnu.org/git/?group=screen Source code repository]

{{Unix commands}}

{{DEFAULTSORT:Gnu Screen}}
[[Category:1987 software]]
[[Category:GNU Project software|Screen]]
[[Category:Termcap]]
[[Category:Terminal multiplexers]]
[[Category:Unix software]]