Editing Shell script (section)

{{short description|Script written for an operating system shell}}
{{About|scripting in Unix-like systems|batch programming in DOS, OS/2 and Windows|Batch file|batch programming in Windows PowerShell shell|Windows PowerShell#Scripting|programming in the shells (cmd.exe) in operating systems of the Windows NT/2000 series|cmd.exe| shell programming, by means of files called Command Scripts or Procedures on Vax/VMS machines|DIGITAL Command Language}}
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[[File:FreeBSD 10 vi RC Firewall.png|thumb|Editing a [[FreeBSD]] shell script for configuring [[ipfirewall]] ]]
A '''shell script''' is a [[computer program]] designed to be run by a [[Unix shell]], a [[command-line interpreter]].<ref>{{ citation | last1 = Kernighan | first1 = Brian W. | author-link = Brian Kernighan | last2 = Pike | first2 = Rob | author2-link = Rob Pike | title = The UNIX Programming Environment | publisher = Prentice Hall, Inc. | year = 1984 | chapter = 3. Using the Shell | page = 94 | quote = The shell is actually a programming language: it has variables, loops, decision-making, and so on. | isbn = 0-13-937699-2 }}</ref> The various dialects of shell scripts are considered to be [[command language]]s. Typical operations performed by shell scripts include file manipulation, program execution, and printing text. A script which sets up the environment, runs the program, and does any necessary cleanup or logging, is called a '''wrapper'''.

The term is also used more generally to mean the automated mode of running an operating system shell;  each operating system uses a particular name for these functions including batch files (MSDos-Win95 stream, [[OS/2]]), command procedures (VMS), and shell scripts ([[Windows NT]] stream and third-party derivatives like [[4NT (shell)|4NT]]—article is at [[cmd.exe]]), and mainframe operating systems are associated with a number of terms.

Shells commonly present in Unix and Unix-like systems include the [[Korn shell]], the [[Bourne shell]], and [[GNU Bash]]. While a Unix operating system may have a different default shell, such as [[Zsh]] on [[macOS]], these shells are typically present for backwards compatibility.