Comparison of command shells

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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

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Shell Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth License Template:Verth Template:Verth Mouse support Unicode
support 		ISO 8601
support 		Template:Verth Stream redirection Configurability Startup/shutdown
scripts 		Template:Verth Logging Template:Verth
Thompson shell UNIX sh 1971 Template:Screen reader-only UNIX UNIX Template:Screen reader-only Yes Text-based CLI No No Template:Screen reader-only Yes Template:Screen reader-only Template:Screen reader-only Template:Screen reader-only Template:Screen reader-only Template:Screen reader-only Template:Screen reader-only
Bourne shell 1977 version 7th Ed. UNIX sh 1977 Yes[1] 7th Ed. UNIX 7th Ed. UNIX, Proprietary[2] Yes Text-based CLI No No Template:Screen reader-only Yes Yes
(arbitrary Page Template:Mono/styles.css has no content.fds[<span title="Script error: No such module "decodeEncode".">citation needed]) 		Yes
(via variables and options) 		Yes
(Page Template:Mono/styles.css has no content..profile) 		Yes
(Unix feature) 		No Yes
Bourne shell current version Various UNIX sh 1977 Yes[3] SunOS-5.x, FreeBSD[4] SunOS-5.x CDDL[5][better source needed] Yes Text-based CLI No Yes[nb 1][better source needed] Template:Screen reader-only Yes Yes
(arbitrary Page Template:Mono/styles.css has no content.fds[<span title="Script error: No such module "decodeEncode".">citation needed]) 		Yes
(via variables and options) 		Yes
(Page Template:Mono/styles.css has no content..profile) 		Yes
(Unix feature) 		Yes[nb 2] Yes
POSIX shell[6] POSIX sh 1992[7] Template:Screen reader-only Template:Screen reader-only POSIX Template:Screen reader-only Template:Screen reader-only Text-based CLI No Yes
if used by configured locale 		Template:Screen reader-only Yes Yes
(arbitrary Page Template:Mono/styles.css has no content.fds[<span title="Script error: No such module "decodeEncode".">citation needed]) 		Yes
(via variables and options) 		Unspecified
(Page Template:Mono/styles.css has no content..profile given as an example) 		Yes
(Unix feature) 		Yes Template:Screen reader-only
bash (v4) POSIX bash, sh 1989[8] Yes GNU, Linux (default for root), macOS 10.3–10.14 GNU, Linux, Haiku, macOS 10.3–10.14 GPL Yes Text-based CLI No Yes[9][better source needed] Yes
(Page Template:Mono/styles.css has no content.printf builtin) 		Yes Yes
(arbitrary Page Template:Mono/styles.css has no content.fds[<span title="Script error: No such module "decodeEncode".">citation needed]) 		Yes
(via variables and options) 		Yes
(Page Template:Mono/styles.css has no content./etc/profile, Page Template:Mono/styles.css has no content..bash_profile, Page Template:Mono/styles.css has no content..bash_login, Page Template:Mono/styles.css has no content..profile, Page Template:Mono/styles.css has no content..bashrc) 		Yes
(Unix feature) 		Yes Yes
csh POSIX csh 1978 Yes SunOS ? BSD Yes Text-based CLI No No ? Yes Yes
(Page Template:Mono/styles.css has no content.stdin, Page Template:Mono/styles.css has no content.stdout, Page Template:Mono/styles.css has no content.stdout+stderr) 		Yes
(via variables and options) 		Yes
(Page Template:Mono/styles.css has no content.~/.cshrc, Page Template:Mono/styles.css has no content.~/.login, Page Template:Mono/styles.css has no content.~/.logout) 		Yes
(Unix feature) 		Yes Yes
tcsh POSIX tcsh, csh 1983[10] Yes FreeBSD (former default for root),[11] formerly Mac OS X ? BSD Yes Text-based CLI No Yes ? Yes Yes
(Page Template:Mono/styles.css has no content.stdin, Page Template:Mono/styles.css has no content.stdout, Page Template:Mono/styles.css has no content.stdout+stderr) 		Yes
(via variables and options) 		Yes
(Page Template:Mono/styles.css has no content./etc/csh.cshrc, Page Template:Mono/styles.css has no content./etc/csh.login, Page Template:Mono/styles.css has no content.~/.tcshrc, Page Template:Mono/styles.css has no content.~/.cshrc, Page Template:Mono/styles.css has no content.~/.history, Page Template:Mono/styles.css has no content.~/.login, Page Template:Mono/styles.css has no content.~/.cshdirs) 		Yes
(Unix feature) 		Yes Yes
Hamilton C shell Win32, OS/2 csh 1988[12] Yes
(OS/2 version no longer maintained) 		Optional Optional Proprietary No Text-based CLI No No Yes
(-t timestamp operator) 		Yes Yes
(Page Template:Mono/styles.css has no content.stdin, Page Template:Mono/styles.css has no content.stdout, Page Template:Mono/styles.css has no content.stdout+stderr) 		Yes
(via variables and options) 		Yes
(via login.csh, startup.csh and logout.csh) 		Yes
(command line option) 		Yes Yes
Scsh POSIX scsh 1994 Yes ? ? BSD-style Yes ? ? ? ? ? Yes ? ? ? ? Yes
ksh (ksh93t+) POSIX ksh 1983[13][14] Yes AIX, HP-UX OpenSolaris Common Public License Yes Text-based CLI No Yes Yes
(Page Template:Mono/styles.css has no content.printf builtin with Page Template:Mono/styles.css has no content.%(%F)T[15]) 		Yes Yes
(Page Template:Mono/styles.css has no content.fds up to 9)[15] 		Yes
(via variables and options) 		Yes
(system and user's Page Template:Mono/styles.css has no content.profile and Page Template:Mono/styles.css has no content.kshrc) 		Yes
(Unix feature) 		Yes Yes
pdksh POSIX ksh, sh 1989? Yes OpenBSD[16] OpenBSD[16] Public domain Yes Text-based CLI No No Template:Screen reader-only Yes Yes
(arbitrary Page Template:Mono/styles.css has no content.fds[<span title="Script error: No such module "decodeEncode".">citation needed]) 		Yes
(via variables and options) 		Yes
(Page Template:Mono/styles.css has no content./etc/profile, Page Template:Mono/styles.css has no content..profile) 		Yes
(Unix feature) 		Yes Yes
zsh POSIX zsh 1990 Yes Deepin, GoboLinux, Grml, macOS 10.15+, Kali 2020.4+, GhostBSD 26.1-R15.0p2+[17] Grml, macOS 10.15+ MIT-style Yes Text-based CLI Yes
via additional code[18] 		Yes Yes
(various internal features involving the date, by using the Page Template:Mono/styles.css has no content.%F Page Template:Mono/styles.css has no content.strftime format[19] and the Page Template:Mono/styles.css has no content.-i option for the Page Template:Mono/styles.css has no content.fc builtin[20]) 		Yes Yes
(Page Template:Mono/styles.css has no content.fds up to 9)[21] 		Yes
(via variables, options, functions, styles, etc.) 		Yes
(system and user's Page Template:Mono/styles.css has no content.zshenv, Page Template:Mono/styles.css has no content.zprofile, Page Template:Mono/styles.css has no content.zshrc, Page Template:Mono/styles.css has no content.zlogin, Page Template:Mono/styles.css has no content.zlogout) 		Yes
(Unix feature) 		Yes Yes
ash POSIX sh 1989 Yes Minix, BusyBox based systems NetBSD, Minix, BusyBox based systems BSD-style Yes Text-based CLI No Partial
(for BusyBox, supported in command-line editing, but not in string handling[22]) 		Template:Screen reader-only Yes Yes
(arbitrary Page Template:Mono/styles.css has no content.fds[<span title="Script error: No such module "decodeEncode".">citation needed]) 		Yes
(via variables and options) 		Yes
(Page Template:Mono/styles.css has no content./etc/profile, Page Template:Mono/styles.css has no content..profile) 		Yes
(Unix feature) 		Yes Yes
CCP CP/M, MP/M (CCP) 1976 (1974) No CP/M (no login), MP/M CP/M, MP/M Freeware (originally proprietary) Yes (originally closed-source) Text-based CLI No No No No No No Yes (automatic via Page Template:Mono/styles.css has no content.$$$.SUB) Partial
(only via external Page Template:Mono/styles.css has no content.SUBMIT command to update Page Template:Mono/styles.css has no content.$$$.SUB) 		No Yes
COMMAND.COM DOS COMMAND 1980 No
(3rd party implementations, not bound to a specific DOS vendor or version, available) 		DOS, Windows 95, 98, SE, ME DOS, Windows 95, 98, SE, ME vendor specific, f.e. MS-EULA,[nb 3] or BSD/GPL (free clones) No (except for OpenDOS, DR-DOS, PTS/DOS and FreeDOS) Text-based CLI No No No (except for DR-DOS) Yes (via Page Template:Mono/styles.css has no content.COMMAND con: or Page Template:Mono/styles.css has no content.CTTY con:) Yes
(Page Template:Mono/styles.css has no content.stdin, Page Template:Mono/styles.css has no content.stdout) 		Yes (via startup parameters and environment variables, DR-DOS also supports Page Template:Mono/styles.css has no content.DIR /C /R user-default switch command) Yes (automatic Page Template:Mono/styles.css has no content.\AUTOEXEC.BAT for primary shell, or explicitly via Page Template:Mono/styles.css has no content./P, Page Template:Mono/styles.css has no content./P:filename.bat or Page Template:Mono/styles.css has no content./K startup options) Yes (via Page Template:Mono/styles.css has no content.CALL command or Page Template:Mono/styles.css has no content./C and Page Template:Mono/styles.css has no content./K startup options) No Yes
OS/2 CMD.EXE OS/2, eComStation, ArcaOS CMD 1987 No OS/2, eComStation, ArcaOS OS/2, eComStation, ArcaOS IBM-EULA[nb 4] No Text-based CLI No No No No Yes
(Page Template:Mono/styles.css has no content.stdin, Page Template:Mono/styles.css has no content.stdout, Page Template:Mono/styles.css has no content.stderr) 		? Partial (only via Page Template:Mono/styles.css has no content./K startup option) Yes (via Page Template:Mono/styles.css has no content.CALL command or Page Template:Mono/styles.css has no content./C and Page Template:Mono/styles.css has no content./K startup options) No Yes
Windows CMD.EXE[nb 5] Win32 CMD 1993 No Windows NT, 2000, XP, Server 2003, Vista Windows NT, 2000, XP, Server 2003, Vista MS-EULA[nb 6] No Text-based CLI No Partial (Page Template:Mono/styles.css has no content.CHCP 65001 for UTF-8, but program arguments are still encoded in local codepage) No No Yes Yes (via registry, startup parameters, and environment variables) Yes (automatic via registry, or explicitly via Page Template:Mono/styles.css has no content./K startup option) Yes (via Page Template:Mono/styles.css has no content.CALL command or Page Template:Mono/styles.css has no content./C and Page Template:Mono/styles.css has no content./K startup options) No Yes
4DOS, NDOS DOS, Windows 95, 98, SE, ME 4DOS, NDOS 1989 (1986) No
(not bound to a specific OS vendor or version) 		Optional Optional MIT License, with restrictions Yes Text-based CLI with TUI extensions Yes (popups, help system, Page Template:Mono/styles.css has no content.%_MOUSE internal variable, Page Template:Mono/styles.css has no content.INKEY /M command) No Yes Yes (via Page Template:Mono/styles.css has no content.CTTY con:, except for Page Template:Mono/styles.css has no content.DRAWBOX, Page Template:Mono/styles.css has no content.DRAWLINE, Page Template:Mono/styles.css has no content.DRAWVLINE, Page Template:Mono/styles.css has no content.LIST, Page Template:Mono/styles.css has no content.SCREEN, Page Template:Mono/styles.css has no content.SCRPUT, Page Template:Mono/styles.css has no content.SELECT, Page Template:Mono/styles.css has no content.VSCRPUT commands and file / directory coloring) Yes
(Page Template:Mono/styles.css has no content.stdin, Page Template:Mono/styles.css has no content.stdout, Page Template:Mono/styles.css has no content.stderr, Page Template:Mono/styles.css has no content.stdout+stderr) 		Yes (via Page Template:Mono/styles.css has no content.4DOS.INI/Page Template:Mono/styles.css has no content.NDOS.INI file, startup parameters, environment variables, Page Template:Mono/styles.css has no content.SETDOS command) Yes (automatic Page Template:Mono/styles.css has no content.\AUTOEXEC.BAT for primary shell and Page Template:Mono/styles.css has no content.4START.BTM/Page Template:Mono/styles.css has no content.4START.BAT as well as Page Template:Mono/styles.css has no content.4EXIT.BTM/Page Template:Mono/styles.css has no content.4EXIT.BAT for any shell, or explicitly via Page Template:Mono/styles.css has no content./P, Page Template:Mono/styles.css has no content./P:dir\filename.ext or Page Template:Mono/styles.css has no content./K startup options) Yes (via Page Template:Mono/styles.css has no content.CALL command or Page Template:Mono/styles.css has no content./C and Page Template:Mono/styles.css has no content./K startup options) Yes Yes
4OS2 OS/2, eComStation, ArcaOS 4OS2 1992 No
(not bound to specific OS/2 versions) 		Optional (but bundled with ArcaOS) Optional Freeware Yes Text-based CLI No No No No Yes
(Page Template:Mono/styles.css has no content.stdin, Page Template:Mono/styles.css has no content.stdout, Page Template:Mono/styles.css has no content.stderr, Page Template:Mono/styles.css has no content.stdout+stderr) 		Yes (via Page Template:Mono/styles.css has no content.4OS2.INI file, startup parameters, environment variables, Page Template:Mono/styles.css has no content.SETDOS command) Yes (automatic via Page Template:Mono/styles.css has no content.4START.CMD/Page Template:Mono/styles.css has no content.4START.BTM as well as Page Template:Mono/styles.css has no content.4EXIT.CMD/Page Template:Mono/styles.css has no content.4EXIT.BTM files, or explicitly via Page Template:Mono/styles.css has no content./K startup.cmd option) Yes (via Page Template:Mono/styles.css has no content.CALL command or Page Template:Mono/styles.css has no content./C and Page Template:Mono/styles.css has no content./K startup options) Yes ?
TCC
(formerly 4NT) 		Win32 TCC 1993 No
(not bound to specific NT versions) 		optional optional Shareware No Text-based CLI (Take Command: GUI) Yes
(console mouse, popups, help system, Page Template:Mono/styles.css has no content.%_XMOUSE, Page Template:Mono/styles.css has no content.%_YMOUSE internal variables, Page Template:Mono/styles.css has no content.INKEY /M command) 		Yes Yes No Yes
(Page Template:Mono/styles.css has no content.stdin, Page Template:Mono/styles.css has no content.stdout, Page Template:Mono/styles.css has no content.stderr, Page Template:Mono/styles.css has no content.stdout+stderr) 		Yes
(via registry, Page Template:Mono/styles.css has no content.TCMD.INI/Page Template:Mono/styles.css has no content.4NT.INI file, startup parameters, environment variables, Page Template:Mono/styles.css has no content.SETDOS command) 		Yes
(automatic via registry and Page Template:Mono/styles.css has no content.TCSTART/Page Template:Mono/styles.css has no content.4START as well as Page Template:Mono/styles.css has no content.TCEXIT/Page Template:Mono/styles.css has no content.4EXIT, or explicitly via Page Template:Mono/styles.css has no content./K startup option) 		Yes
(via Page Template:Mono/styles.css has no content.CALL command or Page Template:Mono/styles.css has no content./C and Page Template:Mono/styles.css has no content./K startup options) 		Yes No
VMS DCL[23] OpenVMS Automatically for login/interactive process 1977[24] Yes VMS VMS Proprietary, bundled in VMS by special license only Text-based CLI with DECwindows/Motif Yes Yes, at least to 1988 standard Yes Yes
(Page Template:Mono/styles.css has no content.sys$input, Page Template:Mono/styles.css has no content.sys$output assignment) 		Yes
(via symbols, logical names, and options) 		Yes
(SYS$MANAGER:SYLOGIN.COM and user defined LOGIN.COM) 		Yes Yes No
PowerShell .NET,
.NET Framework 		PowerShell 2006 Yes Windows 10, 8, Server 2008, 7[nb 7] Windows 10, 8, Server 2008, 7 MIT-style Yes Graphical CLI Yes Yes Yes Yes Yes Yes
(via variables and options) 		Yes
(%USERPROFILE%\Documents \WindowsPowerShell\Microsoft.PowerShell_profile.ps1) 		Yes
(PowerShell feature) 		Yes No
rc Plan 9, POSIX rc 1989 Yes Plan 9, Version 10 Unix Plan 9, Version 10 Unix MIT License[25] Yes Text-based CLI ? Yes Yes ? Yes Yes
(via options) 		Yes
(Page Template:Mono/styles.css has no content.$HOME/.rcrc) 		Yes ? Yes
BeanShell Java ? 2005 Yes ? ? LGPL ? ? ? Yes ? ? Yes ? ? ? ? No
fish POSIX fish 2005[26] Yes GhostBSD ? GPL Yes Text-based CLI ? Yes ? ? Yes
(arbitrary Page Template:Mono/styles.css has no content.fds[<span title="Script error: No such module "decodeEncode".">citation needed]) 		Yes
(through environment variables and via web interface through Page Template:Mono/styles.css has no content.fish_config) 		Yes
(Page Template:Mono/styles.css has no content./etc/fish/config.fish and Page Template:Mono/styles.css has no content.~/.config/fish/config.fish) 		Yes
(Unix feature) 		Yes
(Page Template:Mono/styles.css has no content.~/.config/fish/fish_history*) 		?
Ion Redox, Linux ion 2015[27] Yes Redox Redox MIT Yes Text-based CLI ? Yes Yes ? Yes
(arbitrary Page Template:Mono/styles.css has no content.fds[<span title="Script error: No such module "decodeEncode".">citation needed]) 		Yes
(follows the XDG Base Directory spec) 		Yes
(Page Template:Mono/styles.css has no content.~/.config/ion/initrc) 		Yes Yes
(Page Template:Mono/styles.css has no content.~/.local/share/ion/history) 		Partial (not distributed as a standalone executable, but it can be built as one)

Interactive features

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Shell Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth Template:Verth
Thompson shell No No No No No No No ? ? No No No No No No No No No No
Bourne shell 1977 version No No No No No No No ? ? No No No No No No Yes No External No
Bourne shell current version No Yes[nb 8] No No Yes[nb 8] No No Yes Yes No Yes (CDPATH, pushd, popd, dirs), CDPATH since SVr4 No No No No Yes No External No
POSIX shell No No No No Yes No No Yes Yes No Yes
(Page Template:Mono/styles.css has no content.CDPATH) 		No No No No Yes No External No
bash (v4.0) Yes Yes Yes Yes[nb 9] Yes No No Yes Yes No Yes
(Page Template:Mono/styles.css has no content.CDPATH, Page Template:Mono/styles.css has no content.pushd, Page Template:Mono/styles.css has no content.popd) 		optional No No No Yes Yes External No
csh Yes Yes No No Yes No No Yes Yes No Yes
(Page Template:Mono/styles.css has no content.cdpath, Page Template:Mono/styles.css has no content.pushd, Page Template:Mono/styles.css has no content.popd) 		optional No No No Yes No External No
tcsh Yes Yes when defined No Yes No No Yes Yes No Yes
(Page Template:Mono/styles.css has no content.cdpath, Page Template:Mono/styles.css has no content.pushd, Page Template:Mono/styles.css has no content.popd) 		optional Yes No No Yes No External No
Hamilton C shell Yes Yes No Yes Yes No No Yes Yes No Yes
(Page Template:Mono/styles.css has no content.cdpath, Page Template:Mono/styles.css has no content.pushd, Page Template:Mono/styles.css has no content.popd) 		No No No No Yes No External No
Scsh No No No No No No No ? ? No No No No No No Yes No External No
ksh (ksh93t+) Yes
(extendable) 		Yes
(extendable) 		No No Yes No No Yes Yes No Yes
(Page Template:Mono/styles.css has no content.cdpath builtin, Page Template:Mono/styles.css has no content.pushd, Page Template:Mono/styles.css has no content.popd implemented as functions) 		No No No No Yes Yes External No
pdksh Yes Yes No No Yes No No Yes Yes No No No No No No Yes Yes External No
zsh Yes Yes Yes Yes[28] Yes Yes[29] Yes
(via Page Template:Mono/styles.css has no content.predict-on or user-defined[30]) 		Yes Yes Third-party extension[31] Yes optional Yes No when defined (as ZLE widgets) Yes Yes External Yes
ash No No No No Yes No No Yes Yes No No No No No No Yes Yes External No
CCP No No No No No No No No No No No No No No No No No No No
COMMAND.COM No No No No No[nb 10][nb 11] No No No No (only in DR-DOS through %$ON%, %$OFF%, %$HEADER%, %$FOOTER%) No No No No No (only single-stepping with COMMAND /Y[32]) No No No (only via external Page Template:Mono/styles.css has no content.CHOICE command, in DR-DOS also via Page Template:Mono/styles.css has no content.SWITCH / Page Template:Mono/styles.css has no content.DRSWITCH internal commands) No No
OS/2
CMD.EXE 		Yes Yes No No Yes No No No No No No No No No No No No No No
Windows
CMD.EXE 		partial partial No No Yes
(Page Template:Mono/styles.css has no content.F8) 		No No No No No Yes
(Page Template:Mono/styles.css has no content.PUSHD, Page Template:Mono/styles.css has no content.POPD) 		No No No No Yes (via Page Template:Mono/styles.css has no content.SET /P command) No No No
4DOS Yes Yes Yes Yes Yes[nb 12][nb 13] No No Yes No No (via popup, extended directory searches, Page Template:Mono/styles.css has no content.CDPATH, Page Template:Mono/styles.css has no content.PUSHD, Page Template:Mono/styles.css has no content.POPD, Page Template:Mono/styles.css has no content.DIRHISTORY, Page Template:Mono/styles.css has no content.DIRS, Page Template:Mono/styles.css has no content.CDD, Page Template:Mono/styles.css has no content.CD - commands and Page Template:Mono/styles.css has no content.%@DIRSTACK[] function) Yes No Yes No Yes (via Page Template:Mono/styles.css has no content.INPUT, Page Template:Mono/styles.css has no content.INKEY and Page Template:Mono/styles.css has no content.ESET commands) Yes (via Page Template:Mono/styles.css has no content.@SELECT[] function, and indirectly via a combination of Page Template:Mono/styles.css has no content.INKEY, Page Template:Mono/styles.css has no content.INPUT, Page Template:Mono/styles.css has no content.SWITCH commands) No Yes
4OS2 ? ? ? ? Yes No No Yes No No Yes Yes No ? No ? ? No Yes
TCC (formerly 4NT) Yes Yes Yes Yes Yes No No Yes No Yes (via popup, extended directory searches, Page Template:Mono/styles.css has no content.CDPATH, Page Template:Mono/styles.css has no content.PUSHD, Page Template:Mono/styles.css has no content.POPD, Page Template:Mono/styles.css has no content.DIRHISTORY, Page Template:Mono/styles.css has no content.DIRS, Page Template:Mono/styles.css has no content.CDD, Page Template:Mono/styles.css has no content.CD - commands and Page Template:Mono/styles.css has no content.%@DIRSTACK[] function) Yes No Yes No Yes (via Page Template:Mono/styles.css has no content.INPUT, Page Template:Mono/styles.css has no content.INKEY, Page Template:Mono/styles.css has no content.ESET and Page Template:Mono/styles.css has no content.SET /P commands) Yes (via Page Template:Mono/styles.css has no content.@SELECT[] function, and indirectly via a combination of Page Template:Mono/styles.css has no content.INKEY, Page Template:Mono/styles.css has no content.INPUT, Page Template:Mono/styles.css has no content.SWITCH commands)[nb 14] No Yes
PowerShell Yes Yes Yes Yes Yes
(Page Template:Mono/styles.css has no content.F8) 		Yes Yes; via PSReadLine[33] module (bundled in v5.0[34]) or in ISE[35] Third-party extension[36] Yes[37] Yes; via PSReadLine[33] module (bundled in v5.0) or in ISE[35] Yes
(multiple stacks; multiple location types;[38] Page Template:Mono/styles.css has no content.Push-Location, Page Template:Mono/styles.css has no content.Pop-Location) 		Yes, in PSReadLine[33] module Yes, in ISE[35] Yes, in ISE[35] Yes Yes[39] Yes[40] Yes, in ISE[35] popup window[41]
rc Yes[nb 15] Yes[nb 15] No No Yes[nb 15] No No No ? No No No No No No ? No No No
BeanShell Yes Yes No No No No No ? ? No No No No No No No No No No
VMS DCL Minimum uniqueness scheme No No No Yes Yes No ? ? No No No No No No Yes No No No
fish Yes Yes Yes[42] Yes[42] Yes No Yes Yes Yes
(built-in helper available[43]) 		Yes Yes Yes Yes Yes[nb 16] Yes, using Page Template:Mono/styles.css has no content.abbr command Yes (via Page Template:Mono/styles.css has no content.fish_config command[44]) No No

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

Template:Main article

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 Script error: No such module "key". 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.[45] 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

Script error: No such module "labelled list hatnote". 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

Template:Main article

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 Script error: No such module "key". key inserts the completion.

Implementations of this feature can differ between shells; for example, PowerShell[46] and zsh[47] use an external module to provide completions, and fish derives its completions from the user's command history.[48]

Directory history, stack or similar features

Script error: No such module "labelled list hatnote". 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[49] 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.[50]

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[33] 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".[51] 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 %COLORDIR% environment variable.

For the Unix/Linux shells, this is a feature of the Page Template:Mono/styles.css has no content.ls 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 %$ON% would be \033[1m in conjunction with ANSI.SYS, \033p for an ASCII terminal or \016 for an IBM or ESC/P printer. Likewise, typical sequences for %$OFF% would be \033[0m, \033q, \024, 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.[52]

An independent project offers syntax highlighting as an add-on to the Z Shell (zsh).[53] This is not part of the shell, however.

PowerShell provides customizable syntax highlighting on the command line through the PSReadLine[33] 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.[54]

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

Context sensitive help

Template:Main article

4DOS, 4OS2, 4NT / Take Command Console and PowerShell (in PowerShell ISE) looks up context-sensitive help information when Script error: No such module "key". is pressed.

Zsh provides various forms of configurable context-sensitive help as part of its Page Template:Mono/styles.css has no content.run-help widget, Page Template:Mono/styles.css has no content._complete_help 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

Template:Sort-under

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 No Yes (via Page Template:Mono/styles.css has no content.trap) No No No No No No No Yes No No
Bourne shell current version Yes since SVR2 Yes (via Page Template:Mono/styles.css has no content.trap) No Yes[nb 8] No No No No No Yes No No
POSIX shell Yes Yes (via Page Template:Mono/styles.css has no content.trap) No Yes No No No No No Yes No No
bash (v4.0) Yes Yes (via Page Template:Mono/styles.css has no content.trap) Yes
(via Page Template:Mono/styles.css has no content.${//} syntax) 		Yes No No Yes Yes No Yes Yes
(Page Template:Mono/styles.css has no content.$RANDOM) 		No
csh No No Yes
(via Page Template:Mono/styles.css has no content.$var:s/// syntax) 		Yes No No Yes No No Yes No No
tcsh No No Yes
(via Page Template:Mono/styles.css has no content.$var:s/// syntax) 		Yes No No Yes No No Yes No No
Hamilton C shell Yes No Yes
(via Page Template:Mono/styles.css has no content.$var:s/// syntax) 		Yes Yes Yes Yes No No Yes Yes (random utility) No
Scsh Yes ? Yes
(via string functions and regular expressions) 		? ? ? Yes ? Yes Yes Yes
(random-integer, random-real) 		Yes
(compiler is Scheme48 virtual machine, via Page Template:Mono/styles.css has no content.scshvm)
ksh (ksh93t+) Yes Yes (via Page Template:Mono/styles.css has no content.trap) Yes
(via Page Template:Mono/styles.css has no content.${//} syntax and builtin commands) 		Yes Yes Yes Yes Yes No Yes Yes
(Page Template:Mono/styles.css has no content.$RANDOM) 		Yes
(compiler is called Page Template:Mono/styles.css has no content.shcomp)
pdksh Yes Yes (via Page Template:Mono/styles.css has no content.trap) No Yes No No Yes No No Yes Yes
(Page Template:Mono/styles.css has no content.$RANDOM) 		No
zsh Yes Yes Yes
(via Page Template:Mono/styles.css has no content.${:s//} and Page Template:Mono/styles.css has no content.${//} syntax) 		Yes Yes Yes
(Page Template:Mono/styles.css has no content.zsh/mathfunc module) 		Yes Yes No Yes Yes
(Page Template:Mono/styles.css has no content.$RANDOM) 		Yes
(built-in Page Template:Mono/styles.css has no content.zcompile command)
ash Yes Yes (via Page Template:Mono/styles.css has no content.trap) No Yes
(since 1992)[55] 		No No No No No Yes No No
CCP No ? No No ? ? No No No No No No
COMMAND.COM No Partial (only Auto-fail (via Page Template:Mono/styles.css has no content.COMMAND /F (or Page Template:Mono/styles.css has no content./N in some versions of DR-DOS)) No No No No No No No No No No
OS/2 CMD.EXE No No No ? No No ? No No No No No
Windows CMD.EXE Yes
(via Page Template:Mono/styles.css has no content.CALL :label) 		No Yes
(via Page Template:Mono/styles.css has no content.SET %varname:expression syntax) 		Yes
(via Page Template:Mono/styles.css has no content.SET /A)[56] 		No No Yes
(via Page Template:Mono/styles.css has no content.SET[57]) 		No No No Yes
(Page Template:Mono/styles.css has no content.%random%) 		No
4DOS Yes Yes
(via Page Template:Mono/styles.css has no content.ON command, optional Auto-fail via Page Template:Mono/styles.css has no content.4DOS /F) 		Yes
(via Page Template:Mono/styles.css has no content.%@Replace[...] function) 		Yes
(via Page Template:Mono/styles.css has no content.SET /A) 		? ? Yes
(via ranges, include lists, Page Template:Mono/styles.css has no content.@file lists and Page Template:Mono/styles.css has no content.FOR command) 		No No Yes Yes
(Page Template:Mono/styles.css has no content.%@Random[...] function) 		Yes
(via Page Template:Mono/styles.css has no content.BATCOMP command)
4OS2 ? ? ? ? ? ? ? ? No Yes Yes (Page Template:Mono/styles.css has no content.%@Random[...] function) ?
TCC (formerly 4NT) Yes Yes
(via Page Template:Mono/styles.css has no content.ON and various Page Template:Mono/styles.css has no content....MONITOR commands) 		Yes
(via Page Template:Mono/styles.css has no content.%@Replace[...] function) 		Yes
(via Page Template:Mono/styles.css has no content.SET /A) 		? ? Yes
(via ranges, include lists, Page Template:Mono/styles.css has no content.@file lists and Page Template:Mono/styles.css has no content.FOR command) 		? No Yes Yes (Page Template:Mono/styles.css has no content.%@Random[...] function) Yes (via Page Template:Mono/styles.css has no content.BATCOMP command)
PowerShell Yes Yes (Try-Catch-Finally) Yes
(Page Template:Mono/styles.css has no content.-replace operator) 		Yes Yes [Math] class[58] Yes Yes Yes[59] Yes Yes Yes, automatic
rc Yes Yes No Yes ? ? Yes ? No Yes No No
BeanShell Yes Yes ? Yes ? ? Yes Yes No Yes Yes Yes
VMS DCL Yes Yes No Yes No yes, for compiled programs Yes No No No No No
fish Yes Yes (via Page Template:Mono/styles.css has no content.trap) Yes, via Page Template:Mono/styles.css has no content.string builtin command[60] Yes Yes Yes Yes No No Yes Yes
(Page Template:Mono/styles.css has no content.random) 		No

String processing and filename matching

Template:Sort-under

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 ? No No Yes
(Page Template:Mono/styles.css has no content.*, Page Template:Mono/styles.css has no content.?, Page Template:Mono/styles.css has no content.[...]) 		No No
Bourne shell recent version Partial (prefix and suffix stripping in variable expansion) No No Yes
(Page Template:Mono/styles.css has no content.*, Page Template:Mono/styles.css has no content.?, Page Template:Mono/styles.css has no content.[...]) 		No No
POSIX shell Partial (prefix and suffix stripping in variable expansion) No No Yes
(Page Template:Mono/styles.css has no content.*, Page Template:Mono/styles.css has no content.?, Page Template:Mono/styles.css has no content.[...]) 		No No
bash (v4.0) Partial (prefix and suffix stripping in variable expansion) Yes Yes Yes
(Page Template:Mono/styles.css has no content.*, Page Template:Mono/styles.css has no content.?, Page Template:Mono/styles.css has no content.[...], Page Template:Mono/styles.css has no content.{...}) 		No Yes (Page Template:Mono/styles.css has no content.**/...)
csh Yes
(:s and other editing operators) 		Yes No Yes No No
tcsh Yes
(:s and other editing operators) 		Yes Yes Yes No No
Hamilton C shell Yes
(:s and other editing operators + substr, strlen, strindex, printf, reverse, upper, lower, concat and other builtin functions) 		Yes No Yes No Yes
(via indefinite directory Page Template:Mono/styles.css has no content."..." wildcard[61])
Scsh ? ? Yes Yes No No
ksh (ksh93t+) Partial (prefix, suffix stripping and string replacement in variable expansion) Yes[62] Yes Yes
(Page Template:Mono/styles.css has no content.*, Page Template:Mono/styles.css has no content.?, Page Template:Mono/styles.css has no content.[...]) 		No Yes (with Page Template:Mono/styles.css has no content.set -G, no following of symlinks)
pdksh ? Yes[62] No Yes No No
zsh Yes (through variable processing: e.g. substring extraction, various transformations via parameter expansion) Yes Yes Yes
(Page Template:Mono/styles.css has no content.*, Page Template:Mono/styles.css has no content.?, Page Template:Mono/styles.css has no content.[...], extended globbing[63]) 		Yes Yes (Page Template:Mono/styles.css has no content.**/... or Page Template:Mono/styles.css has no content.***/... to follow symlinks)
ash ? ? No Yes No No
CCP No No No No No No
COMMAND.COM No No No Yes
(Page Template:Mono/styles.css has no content.*, Page Template:Mono/styles.css has no content.?) 		No No
OS/2 CMD.EXE No No No Yes
(Page Template:Mono/styles.css has no content.*, Page Template:Mono/styles.css has no content.?) 		Partial (only in Page Template:Mono/styles.css has no content.DIR /A:... command) No
Windows CMD.EXE Partial (only through Page Template:Mono/styles.css has no content.FOR /F and Page Template:Mono/styles.css has no content.SET /A) No No[nb 17] Yes
(Page Template:Mono/styles.css has no content.*, Page Template:Mono/styles.css has no content.?) 		Partial (only in Page Template:Mono/styles.css has no content.DIR /A:... command) Yes (via Page Template:Mono/styles.css has no content.FOR /R command, or, where available, indirectly via Page Template:Mono/styles.css has no content./S subdir option)
4DOS Yes (through variable functions Page Template:Mono/styles.css has no content.%@...[], extended environment variable processing, various string commands and Page Template:Mono/styles.css has no content.FOR /F and Page Template:Mono/styles.css has no content.SET /A) No No Yes
(Page Template:Mono/styles.css has no content.*, Page Template:Mono/styles.css has no content.?, Page Template:Mono/styles.css has no content.[...], extended wildcards, Page Template:Mono/styles.css has no content.SELECT popup command) 		Yes (via Page Template:Mono/styles.css has no content./A:... attribute and Page Template:Mono/styles.css has no content./I"..." description options and Page Template:Mono/styles.css has no content./[S...] size, Page Template:Mono/styles.css has no content./[T...] time, Page Template:Mono/styles.css has no content./[D...] date, and Page Template:Mono/styles.css has no content./[!...] file exclusion ranges) Yes (via Page Template:Mono/styles.css has no content.FOR /R command, or indirectly via Page Template:Mono/styles.css has no content.GLOBAL command or, where available, Page Template:Mono/styles.css has no content./S subdir option)
4OS2 ? No No ? ? ?
TCC (formerly 4NT) Yes (through variable functions Page Template:Mono/styles.css has no content.%@...[], extended environment variable processing, various string commands and Page Template:Mono/styles.css has no content.FOR /F and Page Template:Mono/styles.css has no content.SET /A) No Yes Yes
(Page Template:Mono/styles.css has no content.*, Page Template:Mono/styles.css has no content.?, Page Template:Mono/styles.css has no content.[...], extended wildcards, Page Template:Mono/styles.css has no content.SELECT popup command) 		Yes (via Page Template:Mono/styles.css has no content./A:... attribute and Page Template:Mono/styles.css has no content./I"..." description options and Page Template:Mono/styles.css has no content./[S...] size, Page Template:Mono/styles.css has no content./[T...] time, Page Template:Mono/styles.css has no content./[D...] date, Page Template:Mono/styles.css has no content./[O...] owner, and Page Template:Mono/styles.css has no content./[!...] file exclusion ranges) Yes (via Page Template:Mono/styles.css has no content.FOR /R command, or indirectly via Page Template:Mono/styles.css has no content.GLOBAL command or, where available, Page Template:Mono/styles.css has no content./S subdir option)
PowerShell Yes
(Concat/Substring/Insert/Remove/Replace, ToLower/ToUpper, Trim/TrimStart/TrimEnd, Compare, Contains/StartsWith/EndWith, Format, IndexOf/LastIndexOf, Pad/PadLeft/PadRight, Split/Join, regular expression functions and other .NET string functions) 		Range operator for numbers[64] Yes
(full regex support)[nb 18] 		Yes
(Page Template:Mono/styles.css has no content.*, Page Template:Mono/styles.css has no content.?, Page Template:Mono/styles.css has no content.[...]) 		? ?
rc ? ? Yes
(~ operator) 		Yes No No
BeanShell ? ? Yes ? ? ?
VMS DCL Yes No No Yes No Yes (via Page Template:Mono/styles.css has no content.[SUBDIR...])
fish Yes
(builtin string function) 		Yes Yes
(via builtin Page Template:Mono/styles.css has no content.string match and Page Template:Mono/styles.css has no content.string replace functions) 		Yes
(Page Template:Mono/styles.css has no content.*, Page Template:Mono/styles.css has no content.?, Page Template:Mono/styles.css has no content.{...}) 		No Yes (Page Template:Mono/styles.css has no content.**/...)

Inter-process communication

Shell Pipes Command substitution Process substitution Subshells TCP/UDP connections as streams Keystroke stacking
Bourne shell bytes concurrent Yes No Yes No N/A[nb 19]
POSIX shell bytes concurrent Yes No Yes No N/A[nb 19]
bash (v4.0) bytes concurrent Yes Yes
(if system supports Page Template:Mono/styles.css has no content./dev/fd/⟨n⟩ or named pipes) 		Yes Yes
(client only) 		N/A[nb 19]
csh bytes concurrent Yes No Yes No N/A[nb 19]
tcsh bytes concurrent Yes No Yes No N/A[nb 19]
Hamilton C shell bytes concurrent Yes No Yes No ?
Scsh text ? ? ? Yes N/A[nb 19]
ksh (ksh93t+) bytes (may contain serialized objects if Page Template:Mono/styles.css has no content.print -C is used) concurrent Yes
(Page Template:Mono/styles.css has no content.$(...) and Page Template:Mono/styles.css has no content.${<space>...;}) 		Yes
(if system supports Page Template:Mono/styles.css has no content./dev/fd/⟨n⟩) 		Yes Yes
(and SCTP support, client only) 		N/A[nb 19]
pdksh bytes concurrent Yes No Yes No N/A[nb 19]
zsh bytes concurrent Yes Yes Yes Yes
(client and server, but only TCP) 		N/A[nb 19]
ash bytes concurrent Yes No Yes No N/A[nb 19]
CCP No No No No No No
COMMAND.COM text sequential temporary files No No Partial (only under DR-DOS multitasker via Page Template:Mono/styles.css has no content.COMMAND.COM /T) No No
OS/2 CMD.EXE text concurrent No No ? No No
Windows CMD.EXE text concurrent Yes
(via Page Template:Mono/styles.css has no content.FOR /F command) 		No Yes
(Backtick: Page Template:Mono/styles.css has no content.` in Page Template:Mono/styles.css has no content.FOR /F usebackq) 		No No
4DOS text sequential temporary files Yes
(via Page Template:Mono/styles.css has no content.FOR /F command) 		? Partial (via Page Template:Mono/styles.css has no content.%@EXECSTR[] and Page Template:Mono/styles.css has no content.%@EXEC[], or via Page Template:Mono/styles.css has no content.SET /M, Page Template:Mono/styles.css has no content.ESET /M and Page Template:Mono/styles.css has no content.UNSET /M and Page Template:Mono/styles.css has no content.%@MASTER[...]) No Yes (via Page Template:Mono/styles.css has no content.KEYSTACK and Page Template:Mono/styles.css has no content.KSTACK)[65]
4OS2 text concurrent ? ? ? No Yes (via Page Template:Mono/styles.css has no content.KEYSTACK)
TCC (formerly 4NT) text concurrent Yes
(via Page Template:Mono/styles.css has no content.FOR /F command) 		? Partial (via Page Template:Mono/styles.css has no content.%@EXECSTR[] and Page Template:Mono/styles.css has no content.%@EXEC[]) Yes (via Page Template:Mono/styles.css has no content.FTP, Page Template:Mono/styles.css has no content.TFTP, Page Template:Mono/styles.css has no content.FTPS, Page Template:Mono/styles.css has no content.SFTP, Page Template:Mono/styles.css has no content.HTTP, Page Template:Mono/styles.css has no content.HTTPS and Page Template:Mono/styles.css has no content.IFTP, client only) Yes (via Page Template:Mono/styles.css has no content.KEYSTACK)
PowerShell objects concurrent Yes No Yes Yes ?
rc text concurrent Yes Yes
(via: Page Template:Mono/styles.css has no content.<{cmd} if system supports Page Template:Mono/styles.css has no content./dev/fd/⟨n⟩) 		Yes No ?
BeanShell not supported ? ? ? Yes ?
VMS DCL text (via Page Template:Mono/styles.css has no content.PIPE command) Yes No Yes
(spawn) 		Yes
(server TCP only) 		No
fish bytes concurrent Yes (Page Template:Mono/styles.css has no content....) No (broken)[66] No No N/A[nb 19]

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

Page Module:Message box/ambox.css has no content.

Template:Sort-under

Shell Secure (password) prompt File/directory passwords Execute permission Restricted shell subset Safe data subset
Bourne shell via Page Template:Mono/styles.css has no content.stty[nb 20] ? N/A[nb 21] Yes No
POSIX shell via Page Template:Mono/styles.css has no content.stty[nb 20] ? N/A[nb 21] No No
bash (v4.0) read -s ? N/A[nb 21] Yes[67] No
csh via Page Template:Mono/styles.css has no content.stty[nb 20] ? N/A[nb 21] Yes No
tcsh via Page Template:Mono/styles.css has no content.stty[nb 20] ? N/A[nb 21] Yes No
Hamilton C shell No No No No No
Scsh via Page Template:Mono/styles.css has no content.stty[nb 20] ? N/A[nb 21] No No
ksh (ksh93t+) via Page Template:Mono/styles.css has no content.stty[nb 20] ? N/A[nb 21] Yes No
pdksh via Page Template:Mono/styles.css has no content.stty[nb 20] ? N/A[nb 21] Yes No
zsh read -s ? N/A[nb 21][nb 22] Yes No
ash via Page Template:Mono/styles.css has no content.stty[nb 20] ? N/A[nb 21] No No
CCP No No No No No
COMMAND.COM Partial (only under DR-DOS, prompts for password if file/directory is protected) Partial (only under DR-DOS via \dirname;dirpwd\filename;filepwd syntax)[nb 23] Partial (only under DR-DOS, if files are password-protected for read and/or execute permission)[nb 24] No No
OS/2 CMD.EXE No No No No No
Windows CMD.EXE No No No No No
4DOS Yes (via INPUT /P or INKEY /P)[nb 25] Partial (only under DR-DOS via \dirname;;dirpwd\filename;;filepwd syntax)[nb 23] Partial (only under DR-DOS, if files are password-protected for read and/or execute permission)[nb 24] No No
4OS2 ? No No No No
TCC (formerly 4NT) Yes (via INPUT /P, INKEY /P or QUERYBOX /P)[nb 25] No No No No
PowerShell Yes[nb 26] No No[nb 27] Yes[nb 28] Yes[68]
rc via Page Template:Mono/styles.css has no content.stty[nb 20] ? N/A[nb 21] No No
BeanShell ? ? ? ? ?
VMS DCL Yes No Yes Yes No
fish read -s ? N/A[nb 21][nb 22] No ?

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.[69]

The shells bash, zsh and PowerShell offer this as a specific feature.[70][71] 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 Page Template:Mono/styles.css has no content.stty external command to switch off/on echoing of input characters.[72] In addition to not echoing back the characters, PowerShell's -AsSecureString 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 permission – 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 was evaluated for the POSIX specification for shells, but not included.[73] However, 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.

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.[74]

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.[75] 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.

Notes

Page Template:Reflist/styles.css has no content.

  1. ^ Since mid 1990s.
  2. ^ if compiled with -DACCT.
  3. ^ MS-DOS and Windows component – covered by a valid license for MS-DOS or Microsoft Windows.
  4. ^ OS/2 component – covered by a valid license for OS/2.
  5. ^ Command extensions enabled, or "CMD /X".
  6. ^ Windows component – covered by a valid license for Microsoft Windows.
  7. ^ Microsoft PowerShell is installed by default on Windows 7 and later. It is an optional download for users of Windows Vista or Windows XP.
  8. ^ a b c current versions from Jörg Schilling.
  9. ^ Alt-Shift-8 or Alt-* will expand to the full matching list of filenames.
  10. ^ Available through the Page Template:Mono/styles.css has no content.DOSKEY add-on.
  11. ^ Available in DR-DOS through Page Template:Mono/styles.css has no content.HISTORY.
  12. ^ Alternatively available through the Page Template:Mono/styles.css has no content.DOSKEY add-on as well.
  13. ^ Alternatively available in DR-DOS through Page Template:Mono/styles.css has no content.HISTORY as well.
  14. ^ TCC has special prompt functions for Yes, No, Cancel, Close, Retry.
  15. ^ a b c Handled by rio, GNU readline, editline or vrl.
  16. ^ The fish shell is an interactive character based input/output surface.
  17. ^ Not available as a shell built-in. External Page Template:Mono/styles.css has no content.FINDSTR /R command is available in most Windows releases.
  18. ^ PowerShell leverages the full .NET regular expression engine which features named captures, zero-width lookahead/-behind, greedy/non-greedy, character classes, level counting etc.
  19. ^ a b c d e f g h i j k 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 Page Template:Mono/styles.css has no content.expect tool).
  20. ^ a b c d e f g h i The shell can use the Page Template:Mono/styles.css has no content.stty 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.
  21. ^ a b c d e f g h i j k l 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.
  22. ^ a b The zsh and fish shells also honor the execute permission for command completion.
  23. ^ a b 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.
  24. ^ a b 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.
  25. ^ a b INPUT /P and INKEY /P echoes back asterisks for each typed character.
  26. ^ Read-Host -AsSecureString 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.
  27. ^ PowerShell script files (Page Template:Mono/styles.css has no content..ps1 files) are by default associated with the Notepad editor, not with the PowerShell execution engine. Invoking a Page Template:Mono/styles.css has no content..ps1 file will launch Notepad rather than executing the script.
  28. ^ Startup scripts per computer/user can import modules and expose a subset the commands/functions available in the modules.

References

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  1. ^ A platform independent version based on the historical UNIX V7 original source code is available from Geoff Collyer
  2. ^ The historic UNIX V7 version is available under a BSD-style license Script error: No such module "webarchive". through The Unix Heritage Society and others.
  3. ^ A platform independent version based on the SVr4/Solaris source code is available from Jörg Schilling
  4. ^ Page Module:Citation/CS1/styles.css has no content.Ferrell, John, "Chapter 2. Default Shell", FreeBSD Quickstart Guide for Linux Users, The FreeBSD Documentation Project, retrieved 2015-07-24
  5. ^ Page Module:Citation/CS1/styles.css has no content."SchilliX-ON / SchilliX-ON Mercurial / [b1d9a2] /usr/src/cmd/sh". Sourceforge.net. Retrieved 2015-07-02.
  6. ^ Page Module:Citation/CS1/styles.css has no content.IEEE and The Open Group (2008). IEEE 1003.1 Standard for Information Technology – Portable Operating System Interface (POSIX): Shell and Utilities, Issue 7.
  7. ^ As part of IEEE Std.1003.2-1992 (POSIX.2); integrated into IEEE Std.1003.1 with the 2001 revision.
  8. ^ Page Module:Citation/CS1/styles.css has no content.Fox, Brian (1989-06-07). Tower Jr., Leonard H. (ed.). "Bash is in beta release!". Newsgroup: gnu.announce. Usenet: 8906080235.AA01983@wheat-chex.ai.mit.edu. Retrieved 2010-10-28.
  9. ^ Page Module:Citation/CS1/styles.css has no content.Cooper, Mendel, "Chapter 37.3.2. Bash, version 4.2", Advanced Bash-Scripting Guide, The Linux Documentation Project, retrieved 2015-04-30, "Bash now supports the \u and \U Unicode escape."
  10. ^ Page Module:Citation/CS1/styles.css has no content.Greer, Ken (1983-10-03). "C shell with command and filename recognition/completion". Newsgroup: net.sources. Retrieved 2010-12-29.
  11. ^ Page Module:Citation/CS1/styles.css has no content."FreeBSD Quickstart Guide for Linux® Users". FreeBSD Documentation Portal. Retrieved 2024-02-04.
  12. ^ Page Module:Citation/CS1/styles.css has no content.Sussman, Ann (1988-12-26). "Hamilton C Shell Speeds Development Of OS/2 Applications" (PDF). PC Week (1988-12-26 - 1989-01-02): 37. Retrieved 2010-11-22.
  13. ^ Page Module:Citation/CS1/styles.css has no content.Gomes, Ron (1983-06-09). "Toronto USENIX Conference Schedule (tentative)". Newsgroup: net.usenix. Retrieved 2010-12-29.
  14. ^ Page Module:Citation/CS1/styles.css has no content.Harris, Guy (1983-10-10). "csh question". Newsgroup: net.flame. Retrieved 2010-12-29.
  15. ^ a b ksh93(1) man page
  16. ^ a b Default shell in OpenBSD is ksh (pdksh).
  17. ^ Page Module:Citation/CS1/styles.css has no content."GhostBSD 26.1-R15.0p2 Is Now Available". GhostBSD News. Retrieved 2026-04-19.
  18. ^ The zsh command line editor is fully configurable and can allow mouse support in various ways such as with Stéphane Chazelas's Page Template:Mono/styles.css has no content.mouse.zsh.
  19. ^ zsh(1) man page and subpages
  20. ^ zshbuiltins(1) man page
  21. ^ Page Module:Citation/CS1/styles.css has no content.Lefevre, Vincent (2015-02-11). "multi-digit file descriptors". zsh-users (Mailing list). Retrieved 2021-12-23.
  22. ^ Page Module:Citation/CS1/styles.css has no content."#782228 - busybox sh doesn't support multibyte characters in string handling - Debian Bug report logs". Bugs.debian.org. 2015-04-09. Retrieved 2015-07-02.
  23. ^ Page Module:Citation/CS1/styles.css has no content."HP OpenVMS DCL Dictionary". Archived from the original on 2007-03-25. Retrieved 2009-03-23.
  24. ^ Page Module:Citation/CS1/styles.css has no content.Kenah, Lawrence J. (1984). VAX/VMS Internals and Data Structures. Digital Press. ISBN 978-3-528-02410-9.
  25. ^ Page Module:Citation/CS1/styles.css has no content.Larabel, Michael (2021-03-23). "Plan 9 Copyright Transferred To Foundation, MIT Licensed Code Released". Phoronix. Retrieved 2021-03-28.
  26. ^ Page Module:Citation/CS1/styles.css has no content.Liljencrantz, Axel (2005-05-17). "Fish - The friendly interactive shell". Retrieved 2013-04-08.
  27. ^ Page Module:Citation/CS1/styles.css has no content.Soller, Jeremy (2015-11-15). "d79c8f511573fb7710abc63b4236a40022914520". Retrieved 2019-08-03.
  28. ^ Page Module:Citation/CS1/styles.css has no content."[Z Shell] Completion System". Zsh.sourceforge.io. Retrieved 2015-02-24.
  29. ^ This applies only on reserved words and other syntactic features.
  30. ^ e.g. via 3rd party such as zsh-autosuggestions
  31. ^ zsh does not feature syntax highlighting, but a 3rd party project exists which offers this capability as an add-on: zsh-syntax-highlighting
  32. ^ Page Module:Citation/CS1/styles.css has no content.Paul, Matthias R. (1997-10-02) [1997-09-29]. "Caldera OpenDOS 7.01/7.02 Update Alpha 3 IBMBIO.COM - README.TXT and BOOT.TXT - A short description of how OpenDOS is booted". Archived from the original on 2003-10-04. Retrieved 2009-03-29. [1]
  33. ^ a b c d e Page Module:Citation/CS1/styles.css has no content.Shirk, Jason (2018-02-15). "PSReadLine: A bash inspired readline implementation for PowerShell" – via GitHub.
  34. ^ Page Module:Citation/CS1/styles.css has no content."Windows PowerShell 5.0". Archived from the original on 17 September 2016. Retrieved 8 September 2016.
  35. ^ a b c d e Page Module:Citation/CS1/styles.css has no content."Windows PowerShell Integrated Scripting Environment (ISE)". Microsoft Technet. Retrieved 2015-09-12.
  36. ^ Page Module:Citation/CS1/styles.css has no content."Get-ChildItemColor". GitHub. 2022-03-18.
  37. ^ Page Module:Citation/CS1/styles.css has no content.sdwheeler. "Write-Host (Microsoft.PowerShell.Utility) - PowerShell". docs.microsoft.com. Retrieved 2022-01-18.
  38. ^ Push-Location (with alias pushd) and Pop-Location (with alias popd) allows multiple location types (directories of file systems, organizational units of Active Directory, nodes of Windows Registry etc) to be pushed onto and popped from location stacks.
  39. ^ 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.
  40. ^ The Page Template:Mono/styles.css has no content.Write-Progress 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.
  41. ^ The Page Template:Mono/styles.css has no content.Show-Command cmdlet inspects the command definition and opens an interactive windows with a named input field for each parameter/switch
  42. ^ a b Page Module:Citation/CS1/styles.css has no content."fish: Documentation". Section Tab completion. Retrieved 2016-01-10.
  43. ^ Page Module:Citation/CS1/styles.css has no content."set_color - set the terminal color — fish-shell 3.1.2 documentation". fishshell.com. Archived from the original on 2020-02-17. Retrieved 2021-02-23.
  44. ^ Page Module:Citation/CS1/styles.css has no content."abbr - manage fish abbreviations — fish-shell 3.1.2 documentation". fishshell.com. Retrieved 2021-02-23.
  45. ^ Page Module:Citation/CS1/styles.css has no content."zsh: 20. Completion System". Zsh.sourceforge.io. 2013-03-06. Retrieved 2013-08-18.
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  47. ^ Page Module:Citation/CS1/styles.css has no content."GitHub - marlonrichert/zsh-autocomplete: 🤖 Real-time type-ahead completion for Zsh. Asynchronous find-as-you-type autocompletion". GitHub. Retrieved 2021-07-25.
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  55. ^ Page Module:Citation/CS1/styles.css has no content."Ash Variants". Archived from the original on 2010-03-10. Retrieved 2014-12-15.
  56. ^ Page Module:Citation/CS1/styles.css has no content."Set - Environment Variable - Windows CMD". SS64.com. Retrieved 2015-02-24.
  57. ^ Page Module:Citation/CS1/styles.css has no content."How to loop through array in batch?". Stack Overflow. Retrieved 2015-02-24.
  58. ^ The .NET System.Math class defines mathematical functions that can be used through the shortcut Page Template:Mono/styles.css has no content.[Math], e.g. Page Template:Mono/styles.css has no content.[Math]::Sin for the sinus function.[2]
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  63. ^ Zsh offers a variety of globbing options.
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  75. ^ Page Module:Citation/CS1/styles.css has no content.Albing, Carl; Vossen, J. P.; Newham, Cameron (2007). Bash cookbook (1st ed.). Sebastopol, California, USA: O'Reilly Media. ISBN 978-0-596-52678-8. [...] is hardly what one thinks of as a passive list of configured variables. It can run other commands (e.g., cat) and use if statements to vary its choices. It even ends by echoing a message. Be careful when you source something, as it's a wide open door into your script.

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