View source for Write (Unix)

{{Short description|Unix command to send messages to another user by writing directly to their terminal}}
{{About|the Unix command|the system call|write (system call)}}
{{Primary sources|date=August 2016}}
{{lowercase}}
{{Infobox software
| name                   = write
| logo                   = 
| screenshot             = 
| screenshot size        = 
| caption                = 
| author                 = [[Dennis Ritchie]],<br />[[Ken Thompson]]
| developer              = [[AT&T Bell Laboratories]]
| released               = {{Start date and age|1971|11|3}}
| latest release version = 
| latest release date    = 
| operating system       = [[Unix]] and [[Unix-like]]
| platform               = [[Cross-platform]]
| genre                  = [[Command (computing)|Command]]
| license                = 
| website                = 
}}
In [[Unix]] and [[Unix-like]] operating systems, {{mono|'''write'''}} is a [[List of Unix commands|utility]] used to [[Instant messaging|send messages]] to another user by writing a message directly to another user's [[Tty (Unix)|TTY]].<ref>{{man|1|write|v7}}</ref>

==History==
The write command was included in the First Edition of the [[Research Unix]] operating system.<ref>{{cite book|title=Unix Programmer's Manual|date=3 November 1971|publisher=Bell Labs|page=write(1)|edition=1st|url=http://www.bell-labs.com/usr/dmr/www/man14.pdf|access-date=9 July 2016|archive-url=https://web.archive.org/web/20160709075913/http://www.bell-labs.com/usr/dmr/www/man14.pdf|archive-date=9 July 2016}}</ref>  A similar command appeared in [[Compatible Time-Sharing System]].<ref>{{cite book |last=Fetter |first=Mirko |date=2019 |title=New Concepts for Presence and Availability in Ubiquitous and Mobile Computing |url=https://books.google.com/books?id=knqIDwAAQBAJ&dq=%22ctss%22+%22write+command%22&pg=PA38 |publisher=[[University of Bamberg]] Press |page=38 |isbn=9783863096236 |quote=The basic concept of sending instantaneously messages to logged in users came with ... CTSS ...}}</ref>

==Sample usage==
The syntax for the write command is:
<syntaxhighlight lang="console">
$ write user [tty]
message
</syntaxhighlight>

The write session is terminated by sending [[End-of-file|EOF]], which can be done by pressing Ctrl+D. The ''tty'' argument is only necessary when a user is logged into more than one terminal.<ref>[https://www.mankier.com/1/write write(1) – util-linux man page]</ref>

A conversation initiated between two users on the same machine:
<syntaxhighlight lang="console">
$ write root pts/7
test
</syntaxhighlight>

Will show up to the user on that console as:
<syntaxhighlight lang="console">
Message from root@wiki on pts/8 at 11:19 ...
test
</syntaxhighlight>

==See also==
{{Wikibooks|Guide to Unix|Commands}}
* [[List of Unix commands]]
* [[talk (Unix)]]
* [[wall (Unix)]]

==References==
{{Reflist}}

{{Unix commands}}

[[Category:Unix user management and support-related utilities]]
[[Category:Standard Unix programs]]
[[Category:Unix SUS2008 utilities]]