Software:Comparison of command shells

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Further information: Software:Shell (computing)
Bash, the default shell on many GNU/Linux systems.

A command shell is a command-line interface to interact with and manipulate a computer's operating system.

General characteristics

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
Thompson shell UNIX sh 1971 N/A UNIX UNIX N/A Yes Text-based CLI No No N/A Yes N/A N/A N/A N/A N/A N/A
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 N/A Yes Yes (via variables and options) Yes (.profile) Yes (Unix feature) No Yes
Bourne shell current version Various UNIX sh 1977 Yes[3] SunOS-5.x, FreeBSD (non-root user)[4] SunOS-5.x Yes Text-based CLI No N/A Yes Yes (via variables and options) Yes (.profile) Yes (Unix feature) Yes[nb 1] Yes
POSIX shell[5] POSIX sh 1992[6] N/A N/A POSIX N/A N/A Text-based CLI No Yes, if used by configured locale N/A Yes Yes (via variables and options) Unspecified (.profile given as an example) Yes (Unix feature) Yes N/A
bash (v4) POSIX bash, sh 1989[7] 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 (printf builtin) Yes Yes (via variables and options) Yes (/etc/profile, .bash_profile, .bash_login, .profile, .bashrc) Yes (Unix feature) Yes Yes
csh POSIX csh 1978 Yes SunOS ? BSD Yes Text-based CLI No No ? Yes Yes (stdin, stdout, stdout+stderr) Yes (via variables and options) Yes (~/.cshrc, ~/.login, ~/.logout) Yes (Unix feature) Yes Yes
tcsh POSIX tcsh, csh 1983[8] Yes FreeBSD (default for root), formerly Mac OS X ? BSD Yes Text-based CLI No Yes ? Yes Yes (stdin, stdout, stdout+stderr) Yes (via variables and options) Yes (/etc/csh.cshrc, /etc/csh.login, ~/.tcshrc, ~/.cshrc, ~/.history, ~/.login, ~/.cshdirs) Yes (Unix feature) Yes Yes
Hamilton C shell Win32, OS/2 csh 1988[9] Yes (OS/2 version no longer maintained) Optional Optional Proprietary No Text-based CLI No No Yes (-t timestamp operator) Yes Yes (stdin, stdout, stdout+stderr) Yes (via variables and options) Yes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[10][11] Yes AIX, HP-UX OpenSolaris Common Public License Yes Text-based CLI No Yes Yes (printf builtin with %(%F)T[12]) Yes Yes (fds up to 9)[12] Yes (via variables and options) Yes (system and user's profile and kshrc) Yes (Unix feature) Yes Yes
pdksh POSIX ksh, sh 1989? Yes OpenBSD[13] OpenBSD[13] Public Domain Yes Text-based CLI No No N/A Yes Yes (via variables and options) Yes (/etc/profile, .profile) Yes (Unix feature) Yes Yes
zsh POSIX zsh 1990 Yes Deepin, GoboLinux, Grml, macOS 10.15+, Kali 2020.4+ Grml, macOS 10.15+ MIT-style Yes Text-based CLI via additional code[14] Yes Yes (various internal features involving the date, by using the %F strftime format[15] and the -i option for the fc builtin[16]) Yes Yes (fds up to 9)[17] Yes (via variables, options, functions, styles, etc.) Yes (system and user's zshenv, zprofile, zshrc, zlogin, 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[18]) N/A Yes Yes (via variables and options) Yes (/etc/profile, .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 $$$.SUB) Partial (only via external SUBMIT command to update $$$.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 2] 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 COMMAND con: or CTTY con:) Yes (stdin, stdout) Yes (via startup parameters and environment variables, DR-DOS also supports DIR /C /R user-default switch command) Yes (automatic \AUTOEXEC.BAT for primary shell, or explicitly via /P, /P:filename.bat or /K startup options) Yes (via CALL command or /C and /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 3] No Text-based CLI No No No No Yes (stdin, stdout, stderr) ? Partial (only via /K startup option) Yes (via CALL command or /C and /K startup options) No Yes
Windows CMD.EXE[nb 4] Win32 CMD 1993 No Windows NT, 2000, XP, Server 2003, Vista Windows NT, 2000, XP, Server 2003, Vista MS-EULA[nb 5] No Text-based CLI No Partial (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 /K startup option) Yes (via CALL command or /C and /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, %_MOUSE internal variable, INKEY /M command) No Yes Yes (via CTTY con:, except for DRAWBOX, DRAWLINE, DRAWVLINE, LIST, SCREEN, SCRPUT, SELECT, VSCRPUT commands and file / directory coloring) Yes (stdin, stdout, stderr, stdout+stderr) Yes (via 4DOS.INI/NDOS.INI file, startup parameters, environment variables, SETDOS command) Yes (automatic \AUTOEXEC.BAT for primary shell and 4START.BTM/4START.BAT as well as 4EXIT.BTM/4EXIT.BAT for any shell, or explicitly via /P, /P:dir\filename.ext or /K startup options) Yes (via CALL command or /C and /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 (stdin, stdout, stderr, stdout+stderr) Yes (via 4OS2.INI file, startup parameters, environment variables, SETDOS command) Yes (automatic via 4START.CMD/4START.BTM as well as 4EXIT.CMD/4EXIT.BTM files, or explicitly via /K startup.cmd option) Yes (via CALL command or /C and /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, %_XMOUSE, %_YMOUSE internal variables, INKEY /M command) Yes Yes No Yes (stdin, stdout, stderr, stdout+stderr) Yes (via registry, TCMD.INI/4NT.INI file, startup parameters, environment variables, SETDOS command) Yes (automatic via registry and TCSTART/4START as well as TCEXIT/4EXIT, or explicitly via /K startup option) Yes (via CALL command or /C and /K startup options) Yes No
VMS DCL[19] OpenVMS Automatically for login/interactive process 1977? 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 (sys$input, sys$output assignment) Yes (via symbols, logical names, and options) Yes (SYS$MANAGER:SYLOGIN.COM and user defined LOGIN.COM) Yes Yes No
PowerShell .NET,
.NET Framework 		PowerShell 2006 Yes Windows 10, 8, Server 2008, 7[nb 6] Windows 10, 8, Server 2008, 7 MIT-style Yes Graphical CLI Yes Yes Yes Yes Yes Yes (via variables and options) Yes (%USERPROFILE%\Documents \WindowsPowerShell\Microsoft.PowerShell_profile.ps1) Yes (PowerShell feature) Yes No
rc Plan 9, POSIX rc 1989 Yes Plan 9, Version 10 Unix Plan 9, Version 10 Unix MIT License[20] Yes Text-based CLI ? Yes Yes ? Yes Yes (via options) Yes ($HOME/.rcrc) Yes ? Yes
BeanShell Java ? 2005 Yes ? ? LGPL ? ? ? Yes ? ? Yes ? ? ? ? No
fish POSIX fish 2005[21] Yes GhostBSD ? GPL Yes Text-based CLI ? Yes ? ? Yes (through environment variables and via web interface through fish_config) Yes (/etc/fish/config.fish and ~/.config/fish/config.fish) Yes (Unix feature) Yes (~/.config/fish/fish_history*) ?
Ion Redox, Linux ion 2015[22] Yes Redox Redox MIT Yes Text-based CLI ? Yes Yes ? Yes (follows the XDG Base Directory spec) Yes (~/.config/ion/initrc) Yes Yes (~/.local/share/ion/history) 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 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 		Command
builder
Thompson shell No 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 No
Bourne shell current version No Yes[nb 7] No No Yes[nb 7] No No Yes Yes No Yes (CDPATH, pushd, popd, dirs), CDPATH since SVr4 No No No No Yes No External No No
POSIX shell No No No No Yes No No Yes Yes No Yes (CDPATH) No No No No Yes No External No No
bash (v4.0) Yes Yes when defined Yes[nb 8] Yes No No Yes Yes No Yes (CDPATH, pushd, popd) optional No No No Yes Yes External No No
csh Yes Yes No No Yes No No Yes Yes No Yes (cdpath, pushd, popd) optional No No No Yes No External No No
tcsh Yes Yes when defined No Yes No No Yes Yes No Yes (cdpath, pushd, popd) optional Yes No No Yes No External No No
Hamilton C shell Yes Yes No Yes Yes No No Yes Yes No Yes (cdpath, pushd, popd) No No No No Yes No External No No
Scsh No No No No No No No ? ? No No No No No No Yes No External No No
ksh (ksh93t+) Yes (extendable) Yes (extendable) No No Yes No No Yes Yes No Yes (cdpath builtin, pushd, popd implemented as functions) No No No No Yes Yes External No No
pdksh Yes Yes No No Yes No No Yes Yes No No No No No No Yes Yes External No No
zsh Yes Yes when defined Yes[23] Yes Yes[24] Yes (via predict-on or user-defined[25]) Yes Yes Third-party extension[26] Yes optional Yes No when defined (as ZLE widgets) Yes Yes External Yes No
ash No No No No Yes No No Yes Yes No No No No No No Yes Yes External No No
CCP No 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 9][nb 10] No No No No (only in DR-DOS through %$ON%, %$OFF%, %$HEADER%, %$FOOTER%) No No No No No (only single-stepping with COMMAND /Y[27]) No No No (only via external CHOICE command, in DR-DOS also via SWITCH / DRSWITCH internal commands) No 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 No
Windows
CMD.EXE 		partial partial No No Yes (F8) No No No No No Yes (PUSHD, POPD) No No No No Yes (via SET /P command) No No No No
4DOS Yes Yes Yes Yes Yes[nb 11][nb 12] No No Yes No No (via popup, extended directory searches, CDPATH, PUSHD, POPD, DIRHISTORY, DIRS, CDD, CD - commands and %@DIRSTACK[] function) Yes No Yes No Yes (via INPUT, INKEY and ESET commands) Yes (via @SELECT[] function, and indirectly via a combination of INKEY, INPUT, SWITCH commands) No Yes No (except for OPTION command for INI file directives)
4OS2 ? ? ? ? Yes No No Yes No No Yes Yes No ? No ? ? No Yes No
TCC (formerly 4NT) Yes Yes Yes Yes Yes No No Yes No Yes (via popup, extended directory searches, CDPATH, PUSHD, POPD, DIRHISTORY, DIRS, CDD, CD - commands and %@DIRSTACK[] function) Yes No Yes No Yes (via INPUT, INKEY, ESET and SET /P commands) Yes (via @SELECT[] function, and indirectly via a combination of INKEY, INPUT, SWITCH commands)[nb 13] No Yes No
PowerShell Yes Yes Yes Yes Yes (F8) Yes Yes; via PSReadLine[28] module (bundled in v5.0[29]) or in ISE[30] Third-party extension[31] Yes[32] Yes; via PSReadLine[28] module (bundled in v5.0) or in ISE[30] Yes (multiple stacks; multiple location types;[33] Push-Location, Pop-Location) Yes, in PSReadLine[28] module Yes, in ISE[30] Yes, in ISE[30] Yes Yes[34] Yes[35] Yes, in ISE[30] popup window[36] Yes, in ISE[30]
rc Yes[nb 14] Yes[nb 14] No No Yes[nb 14] No 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 No
VMS DCL Minimum uniqueness scheme No No No Yes Yes No ? ? No No No No No No Yes No No No No
fish Yes Yes when defined or parsable in man pages[37] Yes[37] Yes No Yes Yes Yes (built-in helper available[38]) Yes Yes Yes Yes Yes[nb 15] Yes, using abbr command Yes (via fish_config command[39]) No No 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 		Command
builder

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. In PowerShell, the Start-Process[40] or Start-Job[41] cmdlets can be used.

Completions

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 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 suggest completions by calling a shell function.[42] 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

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

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.

PowerShell allows commands, functions and scripts to define arguments/parameters as mandatory. The shell determines prior to invocation if there is any mandatory arguments/parameters which have not been bound, and will then prompt the user for the value(s) before actual invocation. [43]

Automatic suggestions

File:Powershell Intellisense example for the Get-Process cmdlet.gifShells featuring automatic suggestions display optional command-line completions as the user types. The PowerShell and fish shells natively support this feature; pressing the key inserts the completion.

Implementations of this feature can differ between shells; for example, PowerShell[44] and zsh[45] use an external module to provide completions, and fish derives its completions from the user's command history.[46]

Directory history, stack or similar features

Further information: Software:Pushd and popd

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[47] in the release of the C shell (csh).

PowerShell allows multiple named stacks to be used. Locations (directories) can be pushed onto/popped from the current stack or a named stack. Any stack can become the current (default) stack. Unlike most other shells, PowerShell's location concept allow location stacks to hold file system locations as well as other location types like e.g. Active Directory organizational units/groups, SQL Server databases/tables/objects, Internet Information Server applications/sites/virtual directories.

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.[48]

Autocorrection

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[28] 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".[49] These are not integrated features of the shells, however.

PowerShell has a built-in command and API functions (to be used when authoring commands) for writing/updating a progress bar. Progress bar messages are sent separates from regular command output and the progress bar is always displayed at the ultimate interactive users console regardless of whether the progress messages originates from an interactive script, from a background job or from a remote session.

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 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

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.[50]

An independent project offers syntax highlighting as an add-on to the Z Shell (zsh).[51] This is not part of the shell, however.

PowerShell provides customizable syntax highlighting on the command line through the PSReadLine[28] 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.[52]

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 is pressed.

Zsh provides various forms of configurable context-sensitive help as part of its run-help widget, _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

Shell Functions Exception handling Search & replace on variable substi­tutions Arith­metic Floating point Math function library Linear arrays or lists Assoc­iative arrays Lambda functions eval func­tion Pseudo­random number generation Bytecode
Bourne shell 1977 version No Yes (via trap) No No No No No No No Yes No No
Bourne shell current version Yes since SVR2 Yes (via trap) No Yes[nb 7] No No No No No Yes No No
POSIX shell Yes Yes (via trap) No Yes No No No No No Yes No No
bash (v4.0) Yes Yes (via trap) Yes (via ${//} syntax) Yes No No Yes Yes No Yes Yes ($RANDOM) No
csh No No Yes (via $var:s/// syntax) Yes No No Yes No No Yes No No
tcsh No No Yes (via $var:s/// syntax) Yes No No Yes No No Yes No No
Hamilton C shell Yes No Yes (via $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 scshvm)
ksh (ksh93t+) Yes Yes (via trap) Yes (via ${//} syntax and builtin commands) Yes Yes Yes Yes Yes No Yes Yes ($RANDOM) Yes (compiler is called shcomp)
pdksh Yes Yes (via trap) No Yes No No Yes No No Yes Yes ($RANDOM) No
zsh Yes Yes Yes (via ${:s//} and ${//} syntax) Yes Yes Yes (zsh/mathfunc module) Yes Yes No Yes Yes ($RANDOM) Yes (built-in zcompile command)
ash Yes Yes (via trap) No Yes (since 1992)[53] 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 COMMAND /F (or /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 CALL :label) No Yes (via SET %varname:expression syntax) Yes (via SET /A)[54] No No Yes (via SET[55]) No No No Yes (%random%) No
4DOS Yes Yes (via ON command, optional Auto-fail via 4DOS /F) Yes (via %@Replace[...] function) Yes (via SET /A) ? ? Yes (via ranges, include lists, @file lists and FOR command) No No Yes Yes (%@Random[...] function) Yes (via BATCOMP command)
4OS2 ? ? ? ? ? ? ? ? No Yes Yes (%@Random[...] function) ?
TCC (formerly 4NT) Yes Yes (via ON and various ...MONITOR commands) Yes (via %@Replace[...] function) Yes (via SET /A) ? ? Yes (via ranges, include lists, @file lists and FOR command) ? No Yes Yes (%@Random[...] function) Yes (via BATCOMP command)
PowerShell Yes Yes (Try-Catch-Finally) Yes (-replace operator) Yes Yes [Math] class[56] Yes Yes Yes[57] 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 trap) Yes, via string builtin command[58] Yes Yes Yes Yes No No Yes Yes (random) 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 ? No No Yes (*, ?, [...]) No No
Bourne shell recent version Partial (prefix and suffix stripping in variable expansion) No No Yes (*, ?, [...]) No No
POSIX shell Partial (prefix and suffix stripping in variable expansion) No No Yes (*, ?, [...]) No No
bash (v4.0) Partial (prefix and suffix stripping in variable expansion) Yes Yes Yes (*, ?, [...], {...}) No Yes (**/...)
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 "..." wildcard[59])
Scsh ? ? Yes Yes No No
ksh (ksh93t+) Partial (prefix, suffix stripping and string replacement in variable expansion) Yes[60] Yes Yes (*, ?, [...]) No Yes (with set -G, no following of symlinks)
pdksh ? Yes[60] No Yes No No
zsh Yes (through variable processing: e.g. substring extraction, various transformations via parameter expansion) Yes Yes Yes (*, ?, [...], extended globbing[61]) Yes Yes (**/... or ***/... to follow symlinks)
ash ? ? No Yes No No
CCP No No No No No No
COMMAND.COM No No No Yes (*, ?) No No
OS/2 CMD.EXE No No No Yes (*, ?) Partial (only in DIR /A:... command) No
Windows CMD.EXE Partial (only through FOR /F and SET /A) No No[nb 16] Yes (*, ?) Partial (only in DIR /A:... command) Yes (via FOR /R command, or, where available, indirectly via /S subdir option)
4DOS Yes (through variable functions %@...[], extended environment variable processing, various string commands and FOR /F and SET /A) No No Yes (*, ?, [...], extended wildcards, SELECT popup command) Yes (via /A:... attribute and /I"..." description options and /[S...] size, /[T...] time, /[D...] date, and /[!...] file exclusion ranges) Yes (via FOR /R command, or indirectly via GLOBAL command or, where available, /S subdir option)
4OS2 ? No No ? ? ?
TCC (formerly 4NT) Yes (through variable functions %@...[], extended environment variable processing, various string commands and FOR /F and SET /A) No Yes Yes (*, ?, [...], extended wildcards, SELECT popup command) Yes (via /A:... attribute and /I"..." description options and /[S...] size, /[T...] time, /[D...] date, /[O...] owner, and /[!...] file exclusion ranges) Yes (via FOR /R command, or indirectly via GLOBAL command or, where available, /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[62] Yes (full regex support)[nb 17] Yes (*, ?, [...]) ? ?
rc ? ? No Yes No No
BeanShell ? ? Yes ? ? ?
VMS DCL Yes No No Yes No Yes (via [SUBDIR...])
fish Yes (builtin string function) Yes yes (via builtin string match and string replace functions) Yes (*, ?, {...}) No Yes (**/...)

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 18]
POSIX shell bytes concurrent Yes No Yes No N/A[nb 18]
bash (v4.0) bytes concurrent Yes Yes (if system supports /dev/fd/⟨n⟩ or named pipes) Yes Yes (client only) N/A[nb 18]
csh bytes concurrent Yes No Yes No N/A[nb 18]
tcsh bytes concurrent Yes No Yes No N/A[nb 18]
Hamilton C shell bytes concurrent Yes No Yes No ?
Scsh text ? ? ? Yes N/A[nb 18]
ksh (ksh93t+) bytes (may contain serialized objects if print -C is used) concurrent Yes ($(...) and ${<space>...;}) Yes (if system supports /dev/fd/⟨n⟩) Yes Yes (and SCTP support, client only) N/A[nb 18]
pdksh bytes concurrent Yes No Yes No N/A[nb 18]
zsh bytes concurrent Yes Yes Yes Yes (client and server, but only TCP) N/A[nb 18]
ash bytes concurrent Yes No Yes No N/A[nb 18]
CCP No No No No No No
COMMAND.COM text sequential temporary files No No Partial (only under DR-DOS multitasker via COMMAND.COM /T) No No
OS/2 CMD.EXE text concurrent No No ? No No
Windows CMD.EXE text concurrent Yes (via FOR /F command) No Yes (Backtick: ` in FOR /F usebackq) No No
4DOS text sequential temporary files Yes (via FOR /F command) ? Partial (via %@EXECSTR[] and %@EXEC[], or via SET /M, ESET /M and UNSET /M and %@MASTER[...]) No
4OS2 text concurrent ? ? ? No Yes (via KEYSTACK)
TCC (formerly 4NT) text concurrent Yes (via FOR /F command) ? Partial (via %@EXECSTR[] and %@EXEC[]) Yes (via FTP, TFTP, FTPS, SFTP, HTTP, HTTPS and IFTP, client only) Yes (via KEYSTACK)
PowerShell objects concurrent Yes No Yes Yes ?
rc text concurrent Yes Yes (via: <{cmd} if system supports /dev/fd/⟨n⟩) Yes No ?
BeanShell not supported ? ? ? Yes ?
VMS DCL text (via PIPE command) Yes No Yes (spawn) Yes (server TCP only) No
fish bytes concurrent Yes (...) No (broken)[63] No No N/A[nb 18]

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 via stty[nb 19] ? N/A[nb 20] Yes No
POSIX shell via stty[nb 19] ? N/A[nb 20] No No
bash (v4.0) read -s ? N/A[nb 20] Yes No
csh via stty[nb 19] ? N/A[nb 20] Yes No
tcsh via stty[nb 19] ? N/A[nb 20] Yes No
Hamilton C shell No No No No No
Scsh via stty[nb 19] ? N/A[nb 20] No No
ksh (ksh93t+) via stty[nb 19] ? N/A[nb 20] Yes No
pdksh via stty[nb 19] ? N/A[nb 20] Yes No
zsh read -s ? N/A[nb 20] Yes No
ash via stty[nb 19] ? N/A[nb 20] Yes 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 21] Partial (only under DR-DOS, if files are password-protected for read and/or execute permission)[nb 22] 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 23] Partial (only under DR-DOS via \dirname;;dirpwd\filename;;filepwd syntax)[nb 21] Partial (only under DR-DOS, if files are password-protected for read and/or execute permission)[nb 22] No No
4OS2 ? No No No No
TCC (formerly 4NT) Yes (via INPUT /P, INKEY /P or QUERYBOX /P)[nb 23] No No No No
PowerShell Yes[nb 24] No No[nb 25] Yes[nb 26] Yes[64]
rc via stty[nb 19] ? N/A[nb 20] Yes[65] No
BeanShell ? ? ? ? ?
VMS DCL Yes No Yes Yes No
fish read -s ? N/A[nb 20] Yes (via fish -l) ?

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.[66]

The shells bash, zsh and PowerShell offer this as a specific feature.[67][68] 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 stty external command to switch off/on echoing of input characters.[69] 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.

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 execve – System Interfaces Reference, The Single UNIX Specification, Issue 7 from The Open Group).

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.[70][71]

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.[72]

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.[73] 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.

PowerShell data sections can contain constants and expressions using a restricted subset of operators and commands.[74] PowerShell data sections are used when e.g. localized strings needs to be read from an external source while protecting against unwanted side effects.


Notes

  1. ↑ if compiled with -DACCT.
  2. ↑ MS-DOS and Windows component – covered by a valid license for MS-DOS or Microsoft Windows.
  3. ↑ OS/2 component – covered by a valid license for OS/2.
  4. ↑ Command extensions enabled, or "CMD /X".
  5. ↑ Windows component – covered by a valid license for Microsoft Windows.
  6. ↑ Microsoft PowerShell is installed by default on Windows 7 and later. It is an optional download for users of Windows Vista or Windows XP.
  7. ↑ 7.0 7.1 7.2 current versions from Jörg Schilling.
  8. ↑ Alt-Shift-8 or Alt-* will expand to the full matching list of filenames.
  9. ↑ Available through the DOSKEY add-on.
  10. ↑ Available in DR-DOS through HISTORY.
  11. ↑ Alternatively available through the DOSKEY add-on as well.
  12. ↑ Alternatively available in DR-DOS through HISTORY as well.
  13. ↑ TCC has special prompt functions for Yes, No, Cancel, Close, Retry.
  14. ↑ 14.0 14.1 14.2 Handled by rio, GNU readline, editline or vrl.
  15. ↑ The fish shell is an interactive character based input/output surface.
  16. ↑ Not available as a shell built-in. External FINDSTR /R command is available in most Windows releases.
  17. ↑ PowerShell leverages the full .NET regular expression engine which features named captures, zero-width lookahead/-behind, greedy/non-greedy, character classes, level counting etc.
  18. ↑ 18.00 18.01 18.02 18.03 18.04 18.05 18.06 18.07 18.08 18.09 18.10 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 expect tool).
  19. ↑ 19.0 19.1 19.2 19.3 19.4 19.5 19.6 19.7 19.8 The shell can use the 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.
  20. ↑ 20.00 20.01 20.02 20.03 20.04 20.05 20.06 20.07 20.08 20.09 20.10 20.11 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.
  21. ↑ 21.0 21.1 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.
  22. ↑ 22.0 22.1 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.
  23. ↑ 23.0 23.1 INPUT /P and INKEY /P echoes back asterisks for each typed character.
  24. ↑ 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.
  25. ↑ PowerShell script files (.ps1 files) are by default associated with the Notepad editor, not with the PowerShell execution engine. Invoking a .ps1 file will launch Notepad rather than executing the script.
  26. ↑ Startup scripts per computer/user can import modules and expose a subset the commands/functions available in the modules.

References

  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 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. ↑ "Chapter 2. Default Shell", FreeBSD Quickstart Guide for Linux Users, The FreeBSD Documentation Project, https://www.freebsd.org/doc/en_US.ISO8859-1/articles/linux-users/shells.html, retrieved 2015-07-24 
  5. ↑ IEEE and The Open Group (2008). IEEE 1003.1 Standard for Information Technology – Portable Operating System Interface (POSIX): Shell and Utilities, Issue 7. 
  6. ↑ As part of IEEE Std.1003.2-1992 (POSIX.2); integrated into IEEE Std.1003.1 with the 2001 revision.
  7. ↑ 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.
  8. ↑ Greer, Ken (1983-10-03). "C shell with command and filename recognition/completion". Newsgroup: net.sources. Retrieved 2010-12-29.
  9. ↑ "Hamilton C Shell Speeds Development Of OS/2 Applications". PC Week (1988-12-26 - 1989-01-02): 37. 1988-12-26. https://hamiltonlabs.com/archives/Hamilton-C-Shell-Speeds-Development-of-OS-2-Applications-Ann-Sussman-PC-Week-Dec-26-1988.pdf. Retrieved 2010-11-22. 
  10. ↑ Gomes, Ron (1983-06-09). "Toronto USENIX Conference Schedule (tentative)". Newsgroup: net.usenix. Retrieved 2010-12-29.
  11. ↑ Harris, Guy (1983-10-10). "csh question". Newsgroup: net.flame. Retrieved 2010-12-29.
  12. ↑ 12.0 12.1 ksh93(1) man page
  13. ↑ 13.0 13.1 Default shell in OpenBSD is ksh (pdksh).
  14. ↑ The zsh command line editor is fully configurable and can allow mouse support in various ways such as with Stéphane Chazelas's mouse.zsh.
  15. ↑ zsh(1) man page and subpages
  16. ↑ zshbuiltins(1) man page
  17. ↑ Lefevre, Vincent (2015-02-11). "multi-digit file descriptors". zsh-users (Mailing list). Retrieved 2021-12-23.
  18. ↑ "#782228 - busybox sh doesn't support multibyte characters in string handling - Debian Bug report logs". Bugs.debian.org. 2015-04-09. https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=782228. 
  19. ↑ "HP OpenVMS DCL Dictionary". http://h71000.www7.hp.com/doc/732final/9996/9996pro_contents.html. 
  20. ↑ Larabel, Michael (2021-03-23). "Plan 9 Copyright Transferred To Foundation, MIT Licensed Code Released". https://www.phoronix.com/scan.php?page=news_item&px=Plan-9-2021. 
  21. ↑ "Fish - The friendly interactive shell". 2005-05-17. https://lwn.net/Articles/136232/. 
  22. ↑ "d79c8f511573fb7710abc63b4236a40022914520". 2015-11-15. https://gitlab.redox-os.org/redox-os/ion/commit/d79c8f511573fb7710abc63b4236a40022914520. 
  23. ↑ "[Z Shell Completion System"]. Zsh.sourceforge.io. https://zsh.sourceforge.io/Doc/Release/Completion-System.html. 
  24. ↑ This applies only on reserved words and other syntactic features.
  25. ↑ e.g. via 3rd party such as zsh-autosuggestions
  26. ↑ zsh does not feature syntax highlighting, but a 3rd party project exists which offers this capability as an add-on: zsh-syntax-highlighting
  27. ↑ "Caldera OpenDOS 7.01/7.02 Update Alpha 3 IBMBIO.COM - README.TXT and BOOT.TXT - A short description of how OpenDOS is booted". 1997-10-02. http://www.uni-bonn.de/~uzs180/download/ibmbioa3.zip.  [1]
  28. ↑ 28.0 28.1 28.2 28.3 28.4 Shirk, Jason (15 February 2018). "PSReadLine: A bash inspired readline implementation for PowerShell". https://github.com/lzybkr/PSReadLine. 
  29. ↑ "Windows PowerShell 5.0". https://msdn.microsoft.com/en-us/powershell/scripting/core-powershell/core-modules/windows-powershell-5.0. 
  30. ↑ 30.0 30.1 30.2 30.3 30.4 30.5 "Windows PowerShell Integrated Scripting Environment (ISE)". Microsoft Technet. https://technet.microsoft.com/en-us/library/dd819514.aspx?f=255&MSPPError=-2147217396. 
  31. ↑ "Get-ChildItemColor". 18 March 2022. https://github.com/joonro/Get-ChildItemColor. 
  32. ↑ sdwheeler. "Write-Host (Microsoft.PowerShell.Utility) - PowerShell". docs.microsoft.com. https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/write-host. 
  33. ↑ 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.
  34. ↑ 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.
  35. ↑ The 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.
  36. ↑ The Show-Command cmdlet inspects the command definition and opens an interactive windows with a named input field for each parameter/switch
  37. ↑ 37.0 37.1 "fish: Documentation". Section Tab completion. http://fishshell.com/docs/current/index.html#completion. 
  38. ↑ "set_color - set the terminal color — fish-shell 3.1.2 documentation". https://fishshell.com/docs/current/cmds/set_color.html. 
  39. ↑ "abbr - manage fish abbreviations — fish-shell 3.1.2 documentation". https://fishshell.com/docs/current/cmds/abbr.html. 
  40. ↑ sdwheeler. "Start-Process (Microsoft.PowerShell.Management) - PowerShell" (in en-us). https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.management/start-process. 
  41. ↑ sdwheeler. "Start-Job (Microsoft.PowerShell.Core) - PowerShell" (in en-us). https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/start-job. 
  42. ↑ "zsh: 20. Completion System". Zsh.sourceforge.io. 2013-03-06. https://zsh.sourceforge.io/Doc/Release/Completion-System.html. 
  43. ↑ "Use PowerShell to Make Mandatory Parameters". Blogs.technet.com. 22 May 2011. http://blogs.technet.com/b/heyscriptingguy/archive/2011/05/22/use-powershell-to-make-mandatory-parameters.aspx. 
  44. ↑ sdwheeler. "What's New in the PowerShell 5.0 ISE - PowerShell" (in en-us). https://docs.microsoft.com/en-us/powershell/scripting/windows-powershell/whats-new/what-s-new-in-the-powershell-50-ise. 
  45. ↑ "GitHub - marlonrichert/zsh-autocomplete: 🤖 Real-time type-ahead completion for Zsh. Asynchronous find-as-you-type autocompletion." (in en). https://github.com/marlonrichert/zsh-autocomplete. 
  46. ↑ "Interactive use — fish-shell 3.3.1 documentation". https://fishshell.com/docs/current/interactive.html#autosuggestions. 
  47. ↑ Hahn, Harley (2009). Harley Hahn's guide to Unix and Linux. Boston: McGraw-Hill Higher Education. ISBN 978-0-07-313361-4. OCLC 184828059. https://www.worldcat.org/oclc/184828059. 
  48. ↑ Concurrent DOS 386 - Multiuser/Multitasking Operating System - User Guide. Digital Research. http://bitsavers.org/pdf/digitalResearch/concurrent/1126-2004-001_Concurrent_DOS_386_Users_Guide_Nov87.pdf. 
  49. ↑ "pv(1): monitor progress of data through pipe - Linux man page". Linux.die.net. http://linux.die.net/man/1/pv. 
  50. ↑ "fish: Tutorial". https://fishshell.com/docs/3.0/tutorial.html#tut_syntax_highlighting. 
  51. ↑ "zsh-users/zsh-syntax-highlighting: Fish shell like syntax highlighting for Zsh". https://github.com/zsh-users/zsh-syntax-highlighting. 
  52. ↑ sdwheeler. "PSReadLine Module - PowerShell" (in en-us). https://learn.microsoft.com/en-us/powershell/module/psreadline/. 
  53. ↑ "Ash Variants". http://www.in-ulm.de/~mascheck/various/ash/. 
  54. ↑ "Set - Environment Variable - Windows CMD". SS64.com. https://ss64.com/nt/set.html. 
  55. ↑ "How to loop through array in batch?". Stack Overflow. https://stackoverflow.com/questions/18462169/how-to-loop-through-array-in-batch. 
  56. ↑ The .NET System.Math class defines mathematical functions that can be used through the shortcut [Math], e.g. [Math]::Sin for the sinus function.[2]
  57. ↑ "Get closure with GetNewClosure". 2009-03-27. https://devblogs.microsoft.com/powershell/get-closure-with-getnewclosure/. 
  58. ↑ "string - manipulate strings — fish-shell 3.1.2 documentation". https://fishshell.com/docs/current/cmds/string.html. 
  59. ↑ Hamilton C shell Language reference: Wildcarding and pattern matching, Hamilton Laboratories, https://hamiltonlabs.com/UserGuide/31-Wildcarding.htm, retrieved 2013-10-29, "... Indefinite Directory: match any number of directory levels – zero or more – whatever it takes to make the rest of the pattern match." 
  60. ↑ 60.0 60.1 Beginning Portable Shell Scripting: From Novice to Professional. Expert's voice in open source. Apress. 21 November 2008 (published 2008). p. 149. ISBN 9781430210436. https://books.google.com/books?id=53zaxy423xcC. Retrieved 2014-09-17. "Brace expansion is available in ksh93, pdksh, bash, and zsh." 
  61. ↑ Zsh offers a variety of globbing options.
  62. ↑ sdwheeler. "about Operators - PowerShell". docs.microsoft.com. https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_operators. 
  63. ↑ "find a way to make 'psub --fifo' safe from deadlock · Issue #1040 · fish-shell/fish-shell". https://github.com/fish-shell/fish-shell/issues/1040. 
  64. ↑ "About Data Sections". Technet.microsoft.com. https://technet.microsoft.com/en-us/library/hh848302.aspx. 
  65. ↑ "Ubuntu Manpage: rc - shell". Manpages.ubuntu.com. 2003-07-17. http://manpages.ubuntu.com/manpages/precise/man1/rc.1.html. 
  66. ↑ "Encrypting Virtual Memory". Center for Information Technology Integration, University of Michigan. http://www.openbsd.org/papers/swapencrypt.ps. 
  67. ↑ "bash - GNU Bourne-Again SHell". https://www.gnu.org/software/bash/manual/html_node/Bash-Builtins.html. "read -s Silent mode. If input is coming from a terminal, characters are not echoed." 
  68. ↑ "Using the Read-Host Cmdlet". https://technet.microsoft.com/en-us/library/ee176935.aspx. "By adding the -assecurestring parameter you can mask the data entered at the prompt" 
  69. ↑ "Linux / Unix Command: stty". Linux.about.com. http://linux.about.com/od/commands/l/blcmdl1_stty.htm. 
  70. ↑ "man sh - shell, the standard command language interpreter / posix" (in fr). Pwet.fr. http://pwet.fr/man/linux/commandes/posix/sh. 
  71. ↑ "Bash Reference Manual: The Restricted Shell". Gnu.org. 2010-12-28. https://www.gnu.org/software/bash/manual/html_node/The-Restricted-Shell.html. 
  72. ↑ "New-PSSessionConfigurationFile". Technet.microsoft.com. https://technet.microsoft.com/en-us/library/hh849712.aspx. 
  73. ↑ Bash cookbook (1st ed.). Sebastopol, California, USA: O'Reilly Media. 2007. 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." 
  74. ↑ "About Data Sections". Microsoft. https://technet.microsoft.com/en-us/library/hh848302.aspx. 

External links



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