Editing Almquist shell (section)

=== Adoption in Debian and Ubuntu ===
{{anchor|Slimness}}Because of its slimness, [[Ubuntu (operating system)|Ubuntu]] decided to adopt Dash as the default <code>/bin/sh</code><ref name="Debian">{{cite web
| url=https://wiki.debian.org/Shell
| title=Non-interactive Shell
| website=[[Debian]] Wiki
| date=2020-01-13
| access-date=2020-02-29}}</ref><ref name="Ubuntu">{{cite web
| url=https://wiki.ubuntu.com/DashAsBinSh
| title=Dash as /bin/sh
| website=[[Ubuntu (operating system)|Ubuntu]] Wiki
| date=2017-12-16
| access-date=2020-02-29}}</ref> in October 2006 with version 6.10. The reason for using Dash is faster [[shell script]] execution,<ref>{{cite book
| author=Neal Krawetz
| title=Ubuntu: Powerful Hacks and Customizations
| year=2011
| publisher=[[John Wiley & Sons]]
| pages=178
| url=https://books.google.com/books?id=h_zclqESvu8C&pg=PT178
| isbn=9781118080382}}</ref> especially during startup of the operating system, compared to previous versions of Debian and Ubuntu that used Bash for this purpose, although [[Bash (Unix shell)|Bash]] is still the default login shell for interactive use.<ref>{{cite book
| author1=Christopher Negus
| author2=Francois Caen
| title=Ubuntu Linux Toolbox
| publisher=John Wiley & Sons
| year=2011
| url=https://books.google.com/books?id=L_IXUtw_w-AC&pg=PA49
| pages=49
| isbn=9781118079140}}</ref>

A result of the shift is that many [[shell script]]s were found making use of [[Bash (Unix shell)|Bash]]-specific functionalities ("bashisms") without properly declaring it in the [[shebang (Unix)|shebang]] line.<ref>{{cite web
| url=https://bugs.launchpad.net/ubuntu/+source/dash/+bug/61463
| title=Script that are using bash could be broken with the new symlink
| author=Egil Hasting
| date=2006-09-20
| publisher=[[Launchpad (website)|Launchpad]]
| access-date=2020-02-29}}</ref><ref>{{cite web
| url=https://bugs.launchpad.net/ubuntu/+source/dash/+bug/141481
| title=dash as #!/bin/sh introduces countless incompatibilities
| author=comotion
| date=2007-09-21
| publisher=Launchpad
| access-date=2020-02-29}}</ref> The problem was first spotted in Ubuntu and the maintainers decided to make all the scripts comply with the [[POSIX]] standard. The changes were later upstreamed to Debian, which eventually adopted Dash as its default {{code|/bin/sh}} too in Debian 6 (Squeeze), released in February 2011.<ref name="Debian"/> As a result, Debian policy was amended to allow script developers to assume a largely POSIX-compliant shell, save for the extensions merged into Dash for convenience ({{code|local}}, {{code|echo -n}}, {{code|test -a / -o}}).<ref name=deb>{{cite web |title=10. Files |url=https://www.debian.org/doc/debian-policy/ch-files.html#scripts |website=Debian Policy Manual v4.5.0.2}}</ref><ref>{{man|1|checkbashisms|ManKier}}</ref> A similar transition has happened in Slackware Linux, although its version of {{code|ash}} is only partially based on Dash.<ref name=vars/>