Comparison of command shells

File:Bash screenshot.png

Screen shot of a terminal showing various Bash commands and resulting output.

This article catalogs comparable aspects of notable operating system shells.

General characteristics

Shell	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small
Thompson shell	UNIX	sh	1971	Template:N/A	UNIX	UNIX	Template:N/A	Template:Yes	Text-based CLI	Template:No	Template:No	Template:N/A	Template:Yes	Template:N/A	Template:N/A	Template:N/A	Template:N/A	Template:N/A	Template:N/A
Bourne shell 1977 version	7th Ed. UNIX	sh	1977	Template:Yes	7th Ed. UNIX	7th Ed. UNIX,	Template:Proprietary	Template:Yes	Text-based CLI	Template:No	Template:No	Template:N/A	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:No	Template:Yes
Bourne shell current version	Various UNIX	sh	1977	Template:Yes	SunOS-5.x, FreeBSD<ref>Template:Citation</ref>	SunOS-5.x	Template:Free	Template:Yes	Text-based CLI	Template:No	Template:Yes<ref group="nb">Since mid 1990s.</ref>Template:Better source needed	Template:N/A	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes<ref group="nb">if compiled with -DACCT.</ref>	Template:Yes
POSIX shell<ref>Template:Cite book</ref>	POSIX	sh	1992<ref>As part of IEEE Std.1003.2-1992 (POSIX.2); integrated into IEEE Std.1003.1 with the 2001 revision.</ref>	Template:N/A	Template:N/A	POSIX	Template:N/A	Template:N/A	Text-based CLI	Template:No	Template:Yes Template:Small	Template:N/A	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Unspecified (Template:Mono given as an example)	Template:Yes Template:Small	Template:Yes	Template:N/A
bash (v4)	POSIX	bash, sh	1989<ref>Template:Cite newsgroup</ref>	Template:Yes	GNU, Linux (default for root), macOS 10.3–10.14	GNU, Linux, Haiku, macOS 10.3–10.14	Template:Free	Template:Yes	Text-based CLI	Template:No	Template:Yes<ref>Template:Citation, "Bash now supports the \u and \U Unicode escape."</ref>Template:Better source needed	Template:Yes Template:Small	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes	Template:Yes
csh	POSIX	csh	1978	Template:Yes	SunOS	Template:Dunno	Template:Free	Template:Yes	Text-based CLI	Template:No	Template:No	Template:Dunno	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes	Template:Yes
tcsh	POSIX	tcsh, csh	1983<ref name="Greer">Template:Cite newsgroup</ref>	Template:Yes	FreeBSD (former default for root),<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref> formerly Mac OS X	Template:Dunno	Template:Free	Template:Yes	Text-based CLI	Template:No	Template:Yes	Template:Dunno	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes	Template:Yes
Hamilton C shell	Win32, OS/2	csh	1988<ref name="PCWeek">Template:Cite journal</ref>	Template:Yes Template:Small	Template:Optional	Template:Optional	Template:Proprietary	Template:No	Text-based CLI	Template:No	Template:No	Template:Yes Template:Small	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes	Template:Yes
Scsh	POSIX	scsh	1994	Template:Yes	Template:Dunno	Template:Dunno	Template:Free	Template:Yes	Template:Dunno	Template:Dunno	Template:Dunno	Template:Dunno	Template:Dunno	Template:Yes	Template:Dunno	Template:Dunno	Template:Dunno	Template:Dunno	Template:Yes
ksh (ksh93t+)	POSIX	ksh	1983<ref name="Gomes">Template:Cite newsgroup</ref><ref name="Harris"> Template:Cite newsgroup</ref>	Template:Yes	AIX, HP-UX	OpenSolaris	Template:Free	Template:Yes	Text-based CLI	Template:No	Template:Yes	Template:Yes Template:Small	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes	Template:Yes
pdksh	POSIX	ksh, sh	1989?	Template:Yes	OpenBSD<ref name="default OpenBSD">Default shell in OpenBSD is ksh (pdksh).</ref>	OpenBSD<ref name="default OpenBSD"/>	Template:Free	Template:Yes	Text-based CLI	Template:No	Template:No	Template:N/A	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes	Template:Yes
zsh	POSIX	zsh	1990	Template:Yes	Deepin, GoboLinux, Grml, macOS 10.15+, Kali 2020.4+	Grml, macOS 10.15+	Template:Free	Template:Yes	Text-based CLI	Template:Yes Template:Small	Template:Yes	Template:Yes Template:Small	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes	Template:Yes
ash	POSIX	sh	1989	Template:Yes	Minix, BusyBox based systems	NetBSD, Minix, BusyBox based systems	Template:Free	Template:Yes	Text-based CLI	Template:No	Template:Partial Template:Small	Template:N/A	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes	Template:Yes
CCP	CP/M, MP/M	(CCP)	1976 (1974)	Template:No	CP/M (no login), MP/M	CP/M, MP/M	Template:Proprietary	Template:Yes (originally closed-source)	Text-based CLI	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:Yes (automatic via Template:Mono)	Template:Partial Template:Small	Template:No	Template:Yes
COMMAND.COM	DOS	COMMAND	1980	Template:No Template:Small	DOS, Windows 95, 98, SE, ME	DOS, Windows 95, 98, SE, ME	vendor specific, f.e. MS-EULA,<ref group="nb">MS-DOS and Windows component – covered by a valid license for MS-DOS or Microsoft Windows.</ref> or BSD/GPL (free clones)	Template:No (except for OpenDOS, DR-DOS, PTS/DOS and FreeDOS)	Text-based CLI	Template:No	Template:No	Template:No (except for DR-DOS)	Template:Yes (via Template:Mono or Template:Mono)	Template:Yes Template:Small	Template:Yes (via startup parameters and environment variables, DR-DOS also supports Template:Mono user-default switch command)	Template:Yes (automatic Template:Mono for primary shell, or explicitly via Template:Mono, Template:Mono or Template:Mono startup options)	Template:Yes (via Template:Mono command or Template:Mono and Template:Mono startup options)	Template:No	Template:Yes
OS/2 CMD.EXE	OS/2, eComStation, ArcaOS	CMD	1987	Template:No	OS/2, eComStation, ArcaOS	OS/2, eComStation, ArcaOS	Template:Proprietary<ref group="nb">OS/2 component – covered by a valid license for OS/2.</ref>	Template:No	Text-based CLI	Template:No	Template:No	Template:No	Template:No	Template:Yes Template:Small	Template:Dunno	Template:Partial (only via Template:Mono startup option)	Template:Yes (via Template:Mono command or Template:Mono and Template:Mono startup options)	Template:No	Template:Yes
Windows CMD.EXE<ref group="nb" name="cmd /x">Command extensions enabled, or "CMD /X".</ref>	Win32	CMD	1993	Template:No	Windows NT, 2000, XP, Server 2003, Vista	Windows NT, 2000, XP, Server 2003, Vista	Template:Proprietary<ref group="nb" name="ReferenceA">Windows component – covered by a valid license for Microsoft Windows.</ref>	Template:No	Text-based CLI	Template:No	Template:Partial (Template:Mono for UTF-8, but program arguments are still encoded in local codepage)	Template:No	Template:No	Template:Yes	Template:Yes (via registry, startup parameters, and environment variables)	Template:Yes (automatic via registry, or explicitly via Template:Mono startup option)	Template:Yes (via Template:Mono command or Template:Mono and Template:Mono startup options)	Template:No	Template:Yes
4DOS, NDOS	DOS, Windows 95, 98, SE, ME	4DOS, NDOS	1989 (1986)	Template:No Template:Small	Template:Optional	Template:Optional	Template:Free	Template:Yes	Text-based CLI with TUI extensions	Template:Yes (popups, help system, Template:Mono internal variable, Template:Mono command)	Template:No	Template:Yes	Template:Yes (via Template:Mono, except for Template:Mono, Template:Mono, Template:Mono, Template:Mono, Template:Mono, Template:Mono, Template:Mono, Template:Mono commands and file / directory coloring)	Template:Yes Template:Small	Template:Yes (via Template:Mono/Template:Mono file, startup parameters, environment variables, Template:Mono command)	Template:Yes (automatic Template:Mono for primary shell and Template:Mono/Template:Mono as well as Template:Mono/Template:Mono for any shell, or explicitly via Template:Mono, Template:Mono or Template:Mono startup options)	Template:Yes (via Template:Mono command or Template:Mono and Template:Mono startup options)	Template:Yes	Template:Yes
4OS2	OS/2, eComStation, ArcaOS	4OS2	1992	Template:No Template:Small	Template:Optional (but bundled with ArcaOS)	Template:Optional	Template:Proprietary	Template:Yes	Text-based CLI	Template:No	Template:No	Template:No	Template:No	Template:Yes Template:Small	Template:Yes (via Template:Mono file, startup parameters, environment variables, Template:Mono command)	Template:Yes (automatic via Template:Mono/Template:Mono as well as Template:Mono/Template:Mono files, or explicitly via Template:Mono option)	Template:Yes (via Template:Mono command or Template:Mono and Template:Mono startup options)	Template:Yes	Template:Dunno
TCC (formerly 4NT)	Win32	TCC	1993	Template:No Template:Small	optional	optional	Template:Proprietary	Template:No	Text-based CLI (Take Command: GUI)	Template:Yes Template:Small	Template:Yes	Template:Yes	Template:No	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes	Template:No
VMS DCL<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	OpenVMS	Template:Small	1977?	Template:Yes	VMS	VMS	Proprietary, bundled in VMS	Template:No	Text-based CLI	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes	Template:Yes	Template:No
PowerShell	.NET, .NET Framework	PowerShell	2006	Template:Yes	Windows 10, 8, Server 2008, 7<ref group="nb" name="optional">Microsoft PowerShell is installed by default on Windows 7 and later. It is an optional download for users of Windows Vista or Windows XP.</ref>	Windows 10, 8, Server 2008, 7	Template:Free	Template:Yes	Graphical CLI	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes	Template:No
rc	Plan 9, POSIX	rc	1989	Template:Yes	Plan 9, Version 10 Unix	Plan 9, Version 10 Unix	Template:Free	Template:Yes	Text-based CLI	Template:Dunno	Template:Yes	Template:Yes	Template:Dunno	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes	Template:Dunno	Template:Yes
BeanShell	Java	Template:Dunno	2005	Template:Yes	Template:Dunno	Template:Dunno	Template:Free	Template:Dunno	Template:Dunno	Template:Dunno	Template:Yes	Template:Dunno	Template:Dunno	Template:Yes	Template:Dunno	Template:Dunno	Template:Dunno	Template:Dunno	Template:No
fish	POSIX	fish	citation	CitationClass=web }}</ref>	Template:Yes	GhostBSD	Template:Dunno	Template:Free	Template:Yes	Text-based CLI	Template:Dunno	Template:Yes	Template:Dunno	Template:Dunno	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Dunno
Ion	Redox, Linux	ion	citation	CitationClass=web }}</ref>	Template:Yes	Redox	Redox	Template:Free	Template:Yes	Text-based CLI	Template:Dunno	Template:Yes	Template:Yes	Template:Dunno	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes	Template:Yes Template:Small	Template:Partial (not distributed as a standalone executable, but it can be built as one)
Shell	Usual environment	Usually invoked	Introduced	Platform-independent	Default login shell in	Default script shell in	License	Source code availability	User interface	Mouse support	Unicode support	ISO 8601 support	Console redirection	Stream redirection	Configurability	Startup/shutdown scripts	Batch scripts	Logging	Available as statically linked, independent single file executable

Interactive features

Shell	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small	Template:Small
Thompson shell	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	?	?	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No
Bourne shell 1977 version	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	?	?	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:Yes	Template:No	Template:Partial	Template:No
Bourne shell current version	Template:No	Template:Yes<ref group="nb" name="ReferenceB">current versions from Jörg Schilling.</ref>	Template:No	Template:No	Template:Yes<ref group="nb" name="ReferenceB"/>	Template:No	Template:No	Template:Yes	Template:Yes	Template:No	Template:Yes (CDPATH, pushd, popd, dirs), CDPATH since SVr4	Template:No	Template:No	Template:No	Template:No	Template:Yes	Template:No	Template:Partial	Template:No
POSIX shell	Template:No	Template:No	Template:No	Template:No	Template:Yes	Template:No	Template:No	Template:Yes	Template:Yes	Template:No	Template:Yes Template:Small	Template:No	Template:No	Template:No	Template:No	Template:Yes	Template:No	Template:Partial	Template:No
bash (v4.0)	Template:Yes	Template:Yes	Template:Yes	Template:Yes<ref group="nb">Alt-Shift-8 or Alt-* will expand to the full matching list of filenames.</ref>	Template:Yes	Template:No	Template:No	Template:Yes	Template:Yes	Template:No	Template:Yes Template:Small	Template:Yes	Template:No	Template:No	Template:No	Template:Yes	Template:Yes	Template:Partial	Template:No
csh	Template:Yes	Template:Yes	Template:No	Template:No	Template:Yes	Template:No	Template:No	Template:Yes	Template:Yes	Template:No	Template:Yes Template:Small	Template:Yes	Template:No	Template:No	Template:No	Template:Yes	Template:No	Template:Partial	Template:No
tcsh	Template:Yes	Template:Yes	Template:Yes2	Template:No	Template:Yes	Template:No	Template:No	Template:Yes	Template:Yes	Template:No	Template:Yes Template:Small	Template:Yes	Template:Yes	Template:No	Template:No	Template:Yes	Template:No	Template:Partial	Template:No
Hamilton C shell	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:Yes	Template:No	Template:No	Template:Yes	Template:Yes	Template:No	Template:Yes Template:Small	Template:No	Template:No	Template:No	Template:No	Template:Yes	Template:No	Template:Partial	Template:No
Scsh	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	?	?	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:Yes	Template:No	Template:Partial	Template:No
ksh (ksh93t+)	Template:Yes Template:Small	Template:Yes Template:Small	Template:No	Template:No	Template:Yes	Template:No	Template:No	Template:Yes	Template:Yes	Template:No	Template:Yes Template:Small	Template:No	Template:No	Template:No	Template:No	Template:Yes	Template:Yes	Template:Partial	Template:No
pdksh	Template:Yes	Template:Yes	Template:No	Template:No	Template:Yes	Template:No	Template:No	Template:Yes	Template:Yes	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:Yes	Template:Yes	Template:Partial	Template:No
zsh	Template:Yes	Template:Yes	Template:Yes	Template:Yes<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Template:Yes	Template:Yes<ref>This applies only on reserved words and other syntactic features.</ref>	Template:Yes Template:Small	Template:Yes	Template:Yes	Template:Partial<ref>zsh does not feature syntax highlighting, but a 3rd party project exists which offers this capability as an add-on: zsh-syntax-highlighting</ref>	Template:Yes	Template:Yes	Template:Yes	Template:No	Template:Yes2	Template:Yes	Template:Yes	Template:Partial	Template:Yes
ash	Template:No	Template:No	Template:No	Template:No	Template:Yes	Template:No	Template:No	Template:Yes	Template:Yes	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:Yes	Template:Yes	Template:Partial	Template:No
CCP	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No
COMMAND.COM	Template:No	Template:No	Template:No	Template:No	Template:No<ref group="nb" name="doskey">Available through the Template:Mono add-on.</ref><ref group="nb" name="drdos">Available in DR-DOS through Template:Mono.</ref>	Template:No	Template:No	Template:No	Template:No (only in DR-DOS through %$ON%, %$OFF%, %$HEADER%, %$FOOTER%)	Template:No	Template:No	Template:No	Template:No	Template:No (only single-stepping with COMMAND /Y<ref name="Paul_1997_OD-A3"/>)	Template:No	Template:No	Template:No (only via external Template:Mono command, in DR-DOS also via Template:Mono / Template:Mono internal commands)	Template:No	Template:No
OS/2 CMD.EXE	Template:Yes	Template:Yes	Template:No	Template:No	Template:Yes	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No
Windows CMD.EXE	Template:Yes2	Template:Yes2	Template:No	Template:No	Template:Yes Template:Small	Template:No	Template:No	Template:No	Template:No	Template:No	Template:Yes Template:Small	Template:No	Template:No	Template:No	Template:No	Template:Yes (via Template:Mono command)	Template:No	Template:No	Template:No
4DOS	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:Yes<ref group="nb" name="doskey_4dos">Alternatively available through the Template:Mono add-on as well.</ref><ref group="nb" name="drdos_4dos">Alternatively available in DR-DOS through Template:Mono as well.</ref>	Template:No	Template:No	Template:Yes	Template:No	Template:No	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:No	Template:Yes (via Template:Mono, Template:Mono and Template:Mono commands)	Template:Yes (via Template:Mono function, and indirectly via a combination of Template:Mono, Template:Mono, Template:Mono commands)	Template:No	Template:Yes
4OS2	?	?	?	?	Template:Yes	Template:No	Template:No	Template:Yes	Template:No	Template:No	Template:Yes	Template:Yes	Template:No	?	Template:No	?	?	Template:No	Template:Yes
TCC (formerly 4NT)	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:No	Template:No	Template:Yes	Template:No	Template:Yes	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:No	Template:Yes (via Template:Mono, Template:Mono, Template:Mono and Template:Mono commands)	Template:Yes (via Template:Mono function, and indirectly via a combination of Template:Mono, Template:Mono, Template:Mono commands)<ref group="nb">TCC has special prompt functions for Yes, No, Cancel, Close, Retry.</ref>	Template:No	Template:Yes
PowerShell	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:Yes Template:Small	Template:Yes	Template:Yes	Template:Partial<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Template:Yes<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Template:Yes	Template:Yes Template:Small	Template:Yes2Yes, in PSReadLine<ref name="PSReadLine"/> module	Template:Yes2Yes, in ISE<ref name="powershell_ise">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Template:Yes2Yes, in ISE<ref name="powershell_ise"/>	Template:Yes	Template:Yes<ref>The $host.ui.PromptForChoice function allows for a menu-style prompt for choices. The prompt works from background jobs as well as from remote sessions, displaying the menu prompt on the console of the controlling session.</ref>	Template:Yes<ref>The Template:Mono cmdlet writes a progress bar which can indicate percentage, remaining seconds etc. The progress bar messages work from background jobs or remote sessions in addition to interactive scripts, i.e. the progress bar is displayed on the console of the controlling session, not as part of the regular output.</ref>	Template:Yes, in ISE<ref name="powershell_ise"/>	Template:Yes<ref>The Template:Mono cmdlet inspects the command definition and opens an interactive windows with a named input field for each parameter/switch</ref>
rc	Template:Yes<ref group="nb" name="rio">Handled by rio, GNU readline, editline or vrl.</ref>	Template:Yes<ref group="nb" name="rio"/>	Template:No	Template:No	Template:Yes<ref group="nb" name="rio"/>	Template:No	Template:No	Template:No	?	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	?	Template:No	Template:No	Template:No
BeanShell	Template:Yes	Template:Yes	Template:No	Template:No	Template:No	Template:No	Template:No	?	?	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No
VMS DCL	Template:Yes	Template:No	Template:No	Template:No	Template:Yes	Template:Yes	Template:No	?	?	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:Yes	Template:No	Template:No	Template:No
fish	Template:Yes	Template:Yes	Template:Yes<ref name="fishcompletion">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Template:Yes<ref name="fishcompletion"/>	Template:Yes	Template:No	Template:Yes	Template:Yes	Template:Yes Template:Small	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:Yes<ref group="nb">The fish shell is an interactive character based input/output surface.</ref>	Template:Yes	Template:Yes	Template:Yes	Template:No	Template:No
Shell	Command name completion	Path completion	Command argument completion	Wildcard completion	Command history	Mandatory argument prompt	Automatic suggestions	Colored directory listings	Text highlighting	Syntax highlighting	Directory history, stack or similar features	Implicit directory change	Auto­correction	Integrated environment	Snippets	Value prompt	Menu/options prompt	Progress indicator	Context sensitive help

Background execution

Background execution allows a shell to run a command without user interaction in the terminal, freeing the command line for additional work with the shell. POSIX shells and other Unix shells allow background execution by using the & character at the end of command.

Completions

File:Command-line-completion-example.gif

Command-line completion in Bash.

Completion features assist the user in typing commands at the command line, by looking for and suggesting matching words for incomplete ones. Completion is generally requested by pressing the completion key (often the Template:Keypress key).

Command name completion is the completion of the name of a command. In most shells, a command can be a program in the command path (usually $PATH), a builtin command, a function or alias.

Path completion is the completion of the path to a file, relative or absolute.

Wildcard completion is a generalization of path completion, where an expression matches any number of files, using any supported syntax for file matching.

Variable completion is the completion of the name of a variable name (environment variable or shell variable). Bash, zsh, and fish have completion for all variable names. PowerShell has completions for environment variable names, shell variable names and — from within user-defined functions — parameter names.

Command argument completion is the completion of a specific command's arguments. There are two types of arguments, named and positional: Named arguments, often called options, are identified by their name or letter preceding a value, whereas positional arguments consist only of the value. Some shells allow completion of argument names, but few support completing values.

Bash, zsh and fish offer parameter name completion through a definition external to the command, distributed in a separate completion definition file. For command parameter name/value completions, these shells assume path/filename completion if no completion is defined for the command. Completion can be set up to dynamically suggest completions by calling a shell function.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The fish shell additionally supports parsing of man pages to extract parameter information that can be used to improve completions/suggestions. In PowerShell, all types of commands (cmdlets, functions, script files) inherently expose data about the names, types and valid value ranges/lists for each argument. This metadata is used by PowerShell to automatically support argument name and value completion for built-in commands/functions, user-defined commands/functions as well as for script files. Individual cmdlets can also define dynamic completion of argument values where the completion values are computed dynamically on the running system.

Command history

Template:Main article Users of a shell may find themselves typing something similar to what they have typed before. Support for command history means that a user can recall a previous command into the command-line editor and edit it before issuing the potentially modified command.

Shells that support completion may also be able to directly complete the command from the command history given a partial/initial part of the previous command.

Most modern shells support command history. Shells which support command history in general also support completion from history rather than just recalling commands from the history. In addition to the plain command text, PowerShell also records execution start- and end time and execution status in the command history.

Mandatory argument prompt

Template:Further Mandatory arguments/parameters are arguments/parameters which must be assigned a value upon invocation of the command, function or script file. A shell that can determine ahead of invocation that there are missing mandatory values, can assist the interactive user by prompting for those values instead of letting the command fail. Having the shell prompt for missing values will allow the author of a script, command or function to mark a parameter as mandatory instead of creating script code to either prompt for the missing values (after determining that it is being run interactively) or fail with a message.

Automatic suggestions

File:Powershell Intellisense example for the Get-Process cmdlet.gif

Command-line completion in PowerShell.

Shells featuring automatic suggestions display optional command-line completions as the user types. The PowerShell and fish shells natively support this feature; pressing the Template:Keypress key inserts the completion.

Implementations of this feature can differ between shells; for example, PowerShell<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and zsh<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> use an external module to provide completions, and fish derives its completions from the user's command history.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Directory history, stack or similar features

Template:Further Shells may record a history of directories the user has been in and allow for fast switching to any recorded location. This is referred to as a "directory stack". The concept had been realized as early as 1978<ref>Template:Cite book</ref> in the release of the C shell (csh).

Command line interpreters 4DOS and its graphical successor Take Command Console also feature a directory stack.

Implicit directory change

A directory name can be used directly as a command which implicitly changes the current location to the directory.

This must be distinguished from an unrelated load drive feature supported by Concurrent DOS, Multiuser DOS, System Manager and REAL/32, where the drive letter L: will be implicitly updated to point to the load path of a loaded application, thereby allowing applications to refer to files residing in their load directory under a standardized drive letter instead of under an absolute path.<ref name="DRI_1987_CDOS_User">Template:Cite book</ref>

Autocorrection

File:Zsh autocompletion and autocorrection demo.gif

Zsh autocompletion and autocorrection demo for a telnet program.

When a command line does not match a command or arguments directly, spell checking can automatically correct common typing mistakes (such as case sensitivity, missing letters). There are two approaches to this; the shell can either suggest probable corrections upon command invocation, or this can happen earlier as part of a completion or autosuggestion.

The tcsh and zsh shells feature optional spell checking/correction, upon command invocation.

Fish does the autocorrection upon completion and autosuggestion. The feature is therefore not in the way when typing out the whole command and pressing enter, whereas extensive use of the tab and right-arrow keys makes the shell mostly case insensitive.

The PSReadLine<ref name="PSReadLine"/> PowerShell module (which is shipped with version 5.0) provides the option to specify a CommandValidationHandler ScriptBlock which runs before submitting the command. This allows for custom correcting of commonly mistyped commands, and verification before actually running the command.

Progress indicator

A shell script (or job) can report progress of long running tasks to the interactive user.

Unix/Linux systems may offer other tools support using progress indicators from scripts or as standalone-commands, such as the program "pv".<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> These are not integrated features of the shells, however.

Colored directory listings

JP Software command-line processors provide user-configurable colorization of file and directory names in directory listings based on their file extension and/or attributes through an optionally defined <syntaxhighlight lang="text" class="" style="" inline="1">%COLORDIR%</syntaxhighlight> environment variable.

For the Unix/Linux shells, this is a feature of the Template:Mono command and the terminal.

Text highlighting

The command line processors in DOS Plus, Multiuser DOS, REAL/32 and in all versions of DR-DOS support a number of optional environment variables to define escape sequences allowing to control text highlighting, reversion or colorization for display or print purposes in commands like TYPE. All mentioned command line processors support %$ON% and %$OFF%. If defined, these sequences will be emitted before and after filenames. A typical sequence for <syntaxhighlight lang="text" class="" style="" inline="1">%$ON%</syntaxhighlight> would be <syntaxhighlight lang="text" class="" style="" inline="1">\033[1m</syntaxhighlight> in conjunction with ANSI.SYS, <syntaxhighlight lang="text" class="" style="" inline="1">\033p</syntaxhighlight> for an ASCII terminal or <syntaxhighlight lang="text" class="" style="" inline="1">\016</syntaxhighlight> for an IBM or ESC/P printer. Likewise, typical sequences for <syntaxhighlight lang="text" class="" style="" inline="1">%$OFF%</syntaxhighlight> would be <syntaxhighlight lang="text" class="" style="" inline="1">\033[0m</syntaxhighlight>, <syntaxhighlight lang="text" class="" style="" inline="1">\033q</syntaxhighlight>, <syntaxhighlight lang="text" class="" style="" inline="1">\024</syntaxhighlight>, respectively. The variables %$HEADER% and %$FOOTER% are only supported by COMMAND.COM in DR-DOS 7.02 and higher to define sequences emitted before and after text blocks in order to control text highlighting, pagination or other formatting options.

For the Unix/Linux shells, this is a feature of the terminal.

Syntax highlighting

Template:Main article A defining feature of the fish shell is built-in syntax highlighting, As the user types, text is colored to represent whether the input is a valid command or not (the executable exists and the user has permissions to run it), and valid file paths are underlined.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

An independent project offers syntax highlighting as an add-on to the Z Shell (zsh).<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> This is not part of the shell, however.

PowerShell provides customizable syntax highlighting on the command line through the PSReadLine<ref name="PSReadLine"/> module. This module can be used with PowerShell v3.0+, and is bundled with v5.0 onwards. It is loaded by default in the command line host "powershell.exe" since v5.0.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Take Command Console (TCC) offers syntax highlighting in the integrated environment.

Context sensitive help

4DOS, 4OS2, 4NT / Take Command Console and PowerShell (in PowerShell ISE) looks up context-sensitive help information when Template:Keypress is pressed.

Zsh provides various forms of configurable context-sensitive help as part of its Template:Mono widget, Template:Mono command, or in the completion of options for some commands.

The fish shell provides brief descriptions of a command's flags during tab completion.

Programming features

Shell	Functions	Exception handling	Search & replace on variable substi­tutions	Template:Verth	Template:Verth	Math function library	Linear arrays or lists	Template:Verth	Template:Verth	Template:Verth	Pseudo­random number generation	Bytecode
Bourne shell 1977 version	Template:No	Template:Yes	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:Yes	Template:No	Template:No
Bourne shell current version	Template:Yes	Template:Yes	Template:No	Template:Yes<ref group="nb" name="ReferenceB"/>	Template:No	Template:No	Template:No	Template:No	Template:No	Template:Yes	Template:No	Template:No
POSIX shell	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:No	Template:No	Template:No	Template:No	Template:No	Template:Yes	Template:No	Template:No
bash (v4.0)	Template:Yes	Template:Yes	Template:Yes Template:Small	Template:Yes	Template:No	Template:No	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:Yes Template:Small	Template:No
csh	Template:No	Template:No	Template:Yes Template:Small	Template:Yes	Template:No	Template:No	Template:Yes	Template:No	Template:No	Template:Yes	Template:No	Template:No
tcsh	Template:Partial	Template:No	Template:Yes Template:Small	Template:Yes	Template:No	Template:No	Template:Yes	Template:No	Template:No	Template:Yes	Template:No	Template:No
Hamilton C shell	Template:Yes	Template:No	Template:Yes Template:Small	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:No	Template:No	Template:Yes	Template:Yes	Template:No
Scsh	Template:Yes	?	Template:Yes Template:Small	?	?	?	Template:Yes	?	Template:Yes	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small
ksh (ksh93t+)	Template:Yes	Template:Yes	Template:Yes Template:Small	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small
pdksh	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:No	Template:No	Template:Yes	Template:No	Template:No	Template:Yes	Template:Yes Template:Small	Template:No
zsh	Template:Yes	Template:Yes	Template:Yes Template:Small	Template:Yes	Template:Yes	Template:Yes Template:Small	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small
ash	Template:Yes	Template:Yes (via Template:Mono)	Template:No	Template:Yes Template:Small	Template:No	Template:No	Template:No	Template:No	Template:No	Template:Yes	Template:No	Template:No
CCP	Template:No	?	Template:No	Template:No	?	?	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No
COMMAND.COM	Template:No	Template:Partial (only Auto-fail (via Template:Mono (or Template:Mono in some versions of DR-DOS))	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No
OS/2 CMD.EXE	Template:No	Template:No	Template:No	?	Template:No	Template:No	?	Template:No	Template:No	Template:No	Template:No	Template:No
Windows CMD.EXE	Template:Yes Template:Small	Template:No	Template:Yes Template:Small	Template:Yes Template:Small	Template:No	Template:No	Template:Yes Template:Small	Template:No	Template:No	Template:No	Template:Yes Template:Small	Template:No
4DOS	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	?	?	Template:Yes Template:Small	Template:No	Template:No	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small
4OS2	?	?	?	?	?	?	?	?	Template:No	Template:Yes	Template:Yes (Template:Mono function)	?
TCC (formerly 4NT)	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes Template:Small	?	?	Template:Yes Template:Small	?	Template:No	Template:Yes	Template:Yes (Template:Mono function)	Template:Yes (via Template:Mono command)
PowerShell	Template:Yes	Template:Yes (Try-Catch-Finally)	Template:Yes Template:Small	Template:Yes	Template:Yes	Template:Yes<ref>The .NET System.Math class defines mathematical functions that can be used through the shortcut Template:Mono, e.g. Template:Mono for the sinus function.[1]</ref>	Template:Yes	Template:Yes	Template:Yes<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Template:Yes	Template:Yes	Template:Yes
rc	Template:Yes	Template:Yes	Template:No	Template:Yes	?	?	Template:Yes	?	Template:No	Template:Yes	Template:No	Template:No
BeanShell	Template:Yes	Template:Yes	?	Template:Yes	?	?	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:Yes	Template:Yes
VMS DCL	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:No	Template:Yes	Template:Yes	Template:No	Template:No	Template:No	Template:No	Template:No
fish	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:No	Template:No	Template:Yes	Template:Yes Template:Small	Template:No

String processing and filename matching

Shell	String processing	Alternation (Brace expansion)	Pattern matching (regular expressions built-in)	Pattern matching (filename globbing)	Globbing qualifiers (filename generation based on file attributes)	Recursive globbing (generating files from any level of subdirectories)
Bourne shell 1977 version	?	Template:No	Template:No	Template:Yes Template:Small	Template:No	Template:No
Bourne shell recent version	Template:Partial (prefix and suffix stripping in variable expansion)	Template:No	Template:No	Template:Yes Template:Small	Template:No	Template:No
POSIX shell	Template:Partial (prefix and suffix stripping in variable expansion)	Template:No	Template:No	Template:Yes Template:Small	Template:No	Template:No
bash (v4.0)	Template:Partial (prefix and suffix stripping in variable expansion)	Template:Yes	Template:Yes	Template:Yes Template:Small	Template:No	Template:Yes (Template:Mono)
csh	Template:Yes Template:Small	Template:Yes	Template:No	Template:Yes	Template:No	Template:No
tcsh	Template:Yes Template:Small	Template:Yes	Template:Yes	Template:Yes	Template:No	Template:No
Hamilton C shell	Template:Yes Template:Small	Template:Yes	Template:No	Template:Yes	Template:No	Template:Yes Template:Small
Scsh	?	?	Template:Yes	Template:Yes	Template:No	Template:No
ksh (ksh93t+)	Template:Partial (prefix, suffix stripping and string replacement in variable expansion)	Template:Yes<ref name="Apress">Template:Cite book</ref>	Template:Yes	Template:Yes Template:Small	Template:No	Template:Yes (with Template:Mono, no following of symlinks)
pdksh	?	Template:Yes<ref name="Apress"/>	Template:No	Template:Yes	Template:No	Template:No
zsh	Template:Yes (through variable processing: e.g. substring extraction, various transformations via parameter expansion)	Template:Yes	Template:Yes	Template:Yes Template:Small	Template:Yes	Template:Yes (Template:Mono or Template:Mono to follow symlinks)
ash	?	?	Template:No	Template:Yes	Template:No	Template:No
CCP	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No
COMMAND.COM	Template:No	Template:No	Template:No	Template:Yes Template:Small	Template:No	Template:No
OS/2 CMD.EXE	Template:No	Template:No	Template:No	Template:Yes Template:Small	Template:Partial (only in Template:Mono command)	Template:No
Windows CMD.EXE	Template:Partial (only through Template:Mono and Template:Mono)	Template:No	Template:No	Template:Yes Template:Small	Template:Partial (only in Template:Mono command)	Template:Yes (via Template:Mono command, or, where available, indirectly via Template:Mono subdir option)
4DOS	Template:Yes (through variable functions Template:Mono, extended environment variable processing, various string commands and Template:Mono and Template:Mono)	Template:No	Template:No	Template:Yes Template:Small	Template:Yes (via Template:Mono attribute and Template:Mono description options and Template:Mono size, Template:Mono time, Template:Mono date, and Template:Mono file exclusion ranges)	Template:Yes (via Template:Mono command, or indirectly via Template:Mono command or, where available, Template:Mono subdir option)
4OS2	?	Template:No	Template:No	?	?	?
TCC (formerly 4NT)	Template:Yes (through variable functions Template:Mono, extended environment variable processing, various string commands and Template:Mono and Template:Mono)	Template:No	Template:Yes	Template:Yes Template:Small	Template:Yes (via Template:Mono attribute and Template:Mono description options and Template:Mono size, Template:Mono time, Template:Mono date, Template:Mono owner, and Template:Mono file exclusion ranges)	Template:Yes (via Template:Mono command, or indirectly via Template:Mono command or, where available, Template:Mono subdir option)
PowerShell	Template:Yes Template:Small	Template:Partial	Template:Yes Template:Small	Template:Yes Template:Small	?	?
rc	?	?	Template:No	Template:Yes	Template:No	Template:No
BeanShell	?	?	Template:Yes	?	?	?
VMS DCL	Template:Yes	Template:No	Template:No	Template:Yes	Template:No	Template:Yes (via Template:Mono)
fish	Template:Yes Template:Small	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:No	Template:Yes (Template:Mono)

Inter-process communication

Shell	Pipes	Command substitution	Process substitution	Subshells	TCP/UDP connections as streams	Keystroke stacking
Bourne shell	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:No	Template:N/A<ref group="nb" name="xautomation">xautomation and xdotool can be used to generate keystrokes under X Window System; or a program can be run in a pseudoterminal to be able to control it (as with the Template:Mono tool).</ref>
POSIX shell	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:No	Template:N/A<ref group="nb" name="xautomation"/>
bash (v4.0)	Template:Yes	Template:Yes	Template:Yes Template:Small	Template:Yes	Template:Yes Template:Small	Template:N/A<ref group="nb" name="xautomation"/>
csh	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:No	Template:N/A<ref group="nb" name="xautomation"/>
tcsh	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:No	Template:N/A<ref group="nb" name="xautomation"/>
Hamilton C shell	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:No	?
Scsh	Template:Yes	?	?	?	Template:Yes	Template:N/A<ref group="nb" name="xautomation"/>
ksh (ksh93t+)	Template:Yes	Template:Yes Template:Small	Template:Yes Template:Small	Template:Yes	Template:Yes Template:Small	Template:N/A<ref group="nb" name="xautomation"/>
pdksh	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:No	Template:N/A<ref group="nb" name="xautomation"/>
zsh	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:Yes Template:Small	Template:N/A<ref group="nb" name="xautomation"/>
ash	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:No	Template:N/A<ref group="nb" name="xautomation"/>
CCP	Template:No	Template:No	Template:No	Template:No	Template:No	Template:No
COMMAND.COM	Template:Yes	Template:No	Template:No	Template:Partial (only under DR-DOS multitasker via Template:Mono)	Template:No	Template:No
OS/2 CMD.EXE	Template:Yes	Template:No	Template:No	?	Template:No	Template:No
Windows CMD.EXE	Template:Yes	Template:Yes Template:Small	Template:No	Template:Yes Template:Small	Template:No	Template:No
4DOS	Template:Yes	Template:Yes Template:Small	?	Template:Partial (via Template:Mono and Template:Mono, or via Template:Mono, Template:Mono and Template:Mono and Template:Mono)	Template:No	Template:Yes (via Template:Mono and Template:Mono)<ref name="4DOS_8.00_HELP">Template:Cite book</ref>
4OS2	Template:Yes	?	?	?	Template:No	Template:Yes (via Template:Mono)
TCC (formerly 4NT)	Template:Yes	Template:Yes Template:Small	?	Template:Partial (via Template:Mono and Template:Mono)	Template:Yes (via Template:Mono, Template:Mono, Template:Mono, Template:Mono, Template:Mono, Template:Mono and Template:Mono, client only)	Template:Yes (via Template:Mono)
PowerShell	Template:Yes	Template:Yes	Template:No	Template:Yes	Template:Yes	?
rc	Template:Yes	Template:Yes	Template:Yes Template:Small	Template:Yes	Template:No	?
BeanShell	Template:No	?	?	?	Template:Yes	?
VMS DCL	Template:Yes	Template:Yes	Template:No	Template:Yes Template:Small	Template:Yes Template:Small	Template:No
fish	Template:Yes	Template:Yes (Template:Mono)	Template:No	Template:No	Template:No	Template:N/A<ref group="nb" name="xautomation"/>

Keystroke stacking

In anticipation of what a given running application may accept as keyboard input, the user of the shell instructs the shell to generate a sequence of simulated keystrokes, which the application will interpret as a keyboard input from an interactive user. By sending keystroke sequences the user may be able to direct the application to perform actions that would be impossible to achieve through input redirection or would otherwise require an interactive user. For example, if an application acts on keystrokes, which cannot be redirected, distinguishes between normal and extended keys, flushes the queue before accepting new input on startup or under certain conditions, or because it does not read through standard input at all. Keystroke stacking typically also provides means to control the timing of simulated keys being sent or to delay new keys until the queue was flushed etc. It also allows to simulate keys which are not present on a keyboard (because the corresponding keys do not physically exist or because a different keyboard layout is being used) and therefore would be impossible to type by a user.

Security features

Shell	Secure (password) prompt	File/directory passwords	Execute permission	Restricted shell subset	Safe data subset
Bourne shell	Template:Some<ref group="nb" name="tty">The shell can use the Template:Mono utility to suppress echoing of typed characters to the screen. This requires multiple steps: 1. reading the current echo state, 2. switching echo off, 3. reading the input, 4. switching echo state back to the original state.</ref>	?	Template:N/A<ref group="nb" name="hashbang">The execute permission is enforced by a separate program, the program loader, by refusing to invoke the interpreter (possibly a shell) specified by the script's hashbang. The interpreter does not enforce the execute permission if invoked directly as the program loader would, with the file as an argument; this only requires read permission, as does piping the file as input to the interpreter, in which case the interpreter cannot see the execute permission.</ref>	Template:Yes	Template:No
POSIX shell	Template:Some<ref group="nb" name="tty"/>	?	Template:N/A<ref group="nb" name="hashbang"/>	Template:No	Template:No
bash (v4.0)	Template:Yes	?	Template:N/A<ref group="nb" name="hashbang"/>	Template:Yes	Template:No
csh	Template:Some<ref group="nb" name="tty"/>	?	Template:N/A<ref group="nb" name="hashbang"/>	Template:Yes	Template:No
tcsh	Template:Some<ref group="nb" name="tty"/>	?	Template:N/A<ref group="nb" name="hashbang"/>	Template:Yes	Template:No
Hamilton C shell	Template:No	Template:No	Template:No	Template:No	Template:No
Scsh	Template:Some<ref group="nb" name="tty"/>	?	Template:N/A<ref group="nb" name="hashbang"/>	Template:No	Template:No
ksh (ksh93t+)	Template:Some<ref group="nb" name="tty"/>	?	Template:N/A<ref group="nb" name="hashbang"/>	Template:Yes	Template:No
pdksh	Template:Some<ref group="nb" name="tty"/>	?	Template:N/A<ref group="nb" name="hashbang"/>	Template:Yes	Template:No
zsh	Template:Yes	?	Template:N/A<ref group="nb" name="hashbang"/><ref group="nb" name="xperm-complete">The zsh and fish shells also honor the execute permission for command completion.</ref>	Template:Yes	Template:No
ash	Template:Some<ref group="nb" name="tty"/>	?	Template:N/A<ref group="nb" name="hashbang"/>	Template:Yes	Template:No
CCP	Template:No	Template:No	Template:No	Template:No	Template:No
COMMAND.COM	Template:Partial (only under DR-DOS, prompts for password if file/directory is protected)	Template:Partial (only under DR-DOS via Template:Mono syntax)<ref group="nb" name="drpwd">Under DR-DOS the password separator for file and directory passwords is a semicolon. This is also supported under 4DOS for as long as the command does not support include lists. Under 4DOS, the password separator must be doubled for all commands supporting include lists in order to distinguish passwords from include lists. Commands not supporting include lists accept both forms. DR-DOS 7.02 and higher optionally accept a doubled semicolon as well, so that doubled semicolons work under both COMMAND.COM and 4DOS regardless of the command executed.</ref>	Template:Partial (only under DR-DOS, if files are password-protected for read and/or execute permission)<ref group="nb" name="drexec">DR-DOS supports file passwords for read/write/delete and optionally execute permissions. Files are not protected by default, but the system can be set up so that f.e. batch scripts require a password to read.</ref>	Template:No	Template:No
OS/2 CMD.EXE	Template:No	Template:No	Template:No	Template:No	Template:No
Windows CMD.EXE	Template:No	Template:No	Template:No	Template:No	Template:No
4DOS	Template:Yes (via Template:Mono or Template:Mono)<ref group="nb" name="input/p">Template:Mono and Template:Mono echoes back asterisks for each typed character.</ref>	Template:Partial (only under DR-DOS via Template:Mono syntax)<ref group="nb" name="drpwd"/>	Template:Partial (only under DR-DOS, if files are password-protected for read and/or execute permission)<ref group="nb" name="drexec"/>	Template:No	Template:No
4OS2	?	Template:No	Template:No	Template:No	Template:No
TCC (formerly 4NT)	Template:Yes (via Template:Mono, Template:Mono or Template:Mono)<ref group="nb" name="input/p"/>	Template:No	Template:No	Template:No	Template:No
PowerShell	Template:Yes<ref group="nb">Template:Mono reads a string of characters from the input device into an encrypted string, one character at a time thus ensuring that there is no memory image of the clear text which could be gleaned from scanning memory, or from crash dumps, memory dumps, paging files, log files or similar.</ref>	Template:No	Template:No<ref group="nb">PowerShell script files (Template:Mono files) are by default associated with the Notepad editor, not with the PowerShell execution engine. Invoking a Template:Mono file will launch Notepad rather than executing the script.</ref>	Template:Yes<ref group="nb">Startup scripts per computer/user can import modules and expose a subset the commands/functions available in the modules.</ref>	Template:Yes<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>
rc	Template:Some<ref group="nb" name="tty"/>	?	Template:N/A<ref group="nb" name="hashbang"/>	Template:Yes<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Template:No
BeanShell	?	?	?	?	?
VMS DCL	Template:Yes	Template:No	Template:Yes	Template:Yes	Template:No
fish	Template:Yes	?	Template:N/A<ref group="nb" name="hashbang"/><ref group="nb" name="xperm-complete"/>	Template:Yes	?

Secure prompt

Some shell scripts need to query the user for sensitive information such as passwords, private digital keys, PIN codes or other confidential information. Sensitive input should not be echoed back to the screen/input device where it could be gleaned by unauthorized persons. Plaintext memory representation of sensitive information should also be avoided as it could allow the information to be compromised, e.g., through swap files, core dumps etc.<ref name="encryptmemory">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

The shells bash, zsh and PowerShell offer this as a specific feature.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Shells which do not offer this as a specific feature may still be able to turn off echoing through some other means. Shells executing on a Unix/Linux operating system can use the Template:Mono external command to switch off/on echoing of input characters.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> In addition to not echoing back the characters, PowerShell's <syntaxhighlight lang="text" class="" style="" inline="1">-AsSecureString</syntaxhighlight> option also encrypts the input character-by-character during the input process, ensuring that the string is never represented unencrypted in memory where it could be compromised through memory dumps, scanning, transcription etc.

Execute permission

Some operating systems define an execute permission which can be granted to users/groups for a file when the file system itself supports it.

On Unix systems, the execute permission controls access to invoking the file as a program, and applies both to executables and scripts. As the permission is enforced in the program loader, no obligation is needed from the invoking program, nor the invoked program, in enforcing the execute permissionTemplate:Snd this also goes for shells and other interpreter programs. The behaviour is mandated by the POSIX C library that is used for interfacing with the kernel. POSIX specifies that the exec family of functions shall fail with EACCESS (permission denied) if the file denies execution permission (see Template:Man).

The execute permission only applies when the script is run directly. If a script is invoked as an argument to the interpreting shell, it will be executed regardless of whether the user holds the execute permission for that script.

Although Windows also specifies an execute permission, none of the Windows-specific shells block script execution if the permission has not been granted.

Restricted shell subset

Several shells can be started or be configured to start in a mode where only a limited set of commands and actions is available to the user. While not a security boundary (the command accessing a resource is blocked rather than the resource) this is nevertheless typically used to restrict users' actions before logging in.

A restricted mode is part of the POSIX specification for shells, and most of the Linux/Unix shells support such a mode where several of the built-in commands are disabled and only external commands from a certain directory can be invoked.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

PowerShell supports restricted modes through session configuration files or session configurations. A session configuration file can define visible (available) cmdlets, aliases, functions, path providers and more.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Safe data subset

Scripts that invoke other scripts can be a security risk as they can potentially execute foreign code in the context of the user who launched the initial script. Scripts will usually be designed to exclusively include scripts from known safe locations; but in some instances, e.g. when offering the user a way to configure the environment or loading localized messages, the script may need to include other scripts/files.<ref>Template:Cite book</ref> One way to address this risk is for the shell to offer a safe subset of commands which can be executed by an included script.

External links

• Template:Cite book
• {{#invoke:citation/CS1|citation

|CitationClass=web }}