The Bourne Again Shell Was First Released in

What is fustigate (Bourne Once again Beat out)?

Bash (Bourne Again Shell) is the gratuitous and enhanced version of the Bourne shell distributed with Linux and GNU operating systems. Bash is similar to the original, merely has added features such every bit command-line editing.

Created to improve on the earlier Bourne beat (named sh), Bash includes features from the Korn beat out and the C shell. Bash is intended to conform to the vanquish standard specified equally part of IEEE POSIX. A command language script written for the Bourne shell should as well run in the fustigate trounce.

Fustigate is released under the GNU General Public License (GPL), and it is bachelor for virtually versions of Unix and Linux and versions have been ported to MS-DOS and Windows.

As explained in the Bash Reference Manual, the name bash is an acronym of "Bourne-again Crush" which is a pun on Stephen Bourne, author of the Bourne trounce. Bash is a superset of the earlier beat out, and generally compatible with Bourne shell programs.

What is a beat out?

In computing, a beat program provides admission to an operating organisation'southward components. The shell gives users (or other programs) a way to get "inside" the system; the shell defines the boundary between inside and outside.

There are two types of operating system shells:

Command-line interface (CLI) shells like bash offer users a curtailed and efficient mode of interacting with the Bone, without requiring the overhead of a graphic user interface.
Graphical user interface (GUI) shells, such as Windows and macOS, are considered easier for beginners to use, but normally as well offer programs that emulate a CLI-based shell for arrangement administrators or other ability users who prefer to interact at a command prompt.

Bash is the most usually used CLI shell for Unix-based OSes, including Linux.

What is bash used for?

Bash, similar other CLIs, is used for whatever computer application that requires precision when working with files and data, specially where large numbers of files or large quantities of data need to be searched, sorted, manipulated or processed in any fashion.

Some of the almost common Fustigate use cases include:

System administrators use Fustigate to manage systems systematically and reproducibly. Organization administrators use Bash to troubleshoot systems that are not functioning every bit desired or expected by logging in to systems and reviewing arrangement configurations and network connections. Organisation administrators also rely on Bash scripts to distribute software updates and patches, to monitor running systems, and to update and configure systems.
Software developers rely on Fustigate for many evolution tasks. Bash tin be used to automate software evolution tasks such as code compilation, debugging source code, modify management and software testing.
Network engineers use Bash to examination, configure and optimize network performance on organizational networks.
Information science researchers apply Fustigate to manage enquiry systems and to acquit out research on those systems.
Hobbyists and power users use Bash to interact with their systems, execute programs and maintain their systems.

Bash is commonly used interactively, but it can too be used to write shell scripts. Nearly any computer task can be automatic using a Bash script. Fustigate scripts tin can be run on-demand or scheduled to run periodically.

How does bash piece of work?

At beginning sight fustigate appears to be a uncomplicated control/response organisation, where users enter commands and fustigate returns the results after those commands are run. All the same, bash is as well a programming platform and users are enabled to write programs that accept input and produce output using crush commands in trounce scripts.

One of the well-nigh bones bash commands, ls, does one thing: listing directory contents. Past itself this command lists only the names of files and subdirectories in the current working directory.

Output from bash ls command without parameters — Output from the fustigate ls command includes only file and directory names.

The ls control has numerous parameters that modify how the results are displayed. Some frequently used parameters used with the ls command include:

ls command-line arguments (parameters)	Purpose
-l	Use a longer, more detailed, list format to include file permissions, file owner, group, size and date/time of creation.
-a	Listing all files and subdirectories, even those that are ordinarily intended to be hidden.
-south	Brandish the size of each file.
-h	Display file and subdirectory sizes in human-readable format using Chiliad, M, Thousand and and so on to point kilobytes, megabytes and gigabytes.
-R	Recursive listing of all files and subdirectories under the electric current working directory.

Used all together, these parameters give the user a much clearer sense of what files and subdirectories are in a directory, when they have last been changed and past whom.

Bash piping pipes — Use pipes to filter out the desired data from bash commands.

Bash enables combining commands past pipage output of one command to exist used as the input for another command. For case, this command can be used to listing all files on a file organization using the -R parameter to specify the listing should be recursive:

[electronic mail protected]:/$ 1s -1ashR

The response to this control, peculiarly when issued from the system root directory, contains too many entries for humans to parse hands. This is where pipes can come into play, in this case, the user can pipe the output from the ls command to the Fustigate text pattern matching command, grep.

The pipe symbol (vertical bar, or "|") directs output from the directory listing into the grep command to return only files and subdirectories with filenames that include the specified text design. This command:

[email protected]:/$ 1s -1ashR |grep 'filename.txt'

returns only files that include the string 'filename.txt' and then this control tin can exist used to locate a specific file.

Some things that are much easier to do interactively from the fustigate command line include:

file and directory management;
checking on network configuration;
editing a configuration file (or any text file); and
showing the difference betwixt two files.

Types of bash commands include:

Elementary commands, which usually are run past themselves or with parameters and variables. For example, the ls command takes parameters as well as variables relating to the directories or files to exist listed.
Pipes, which are used to link the output of one or more commands every bit input to other commands.
Lists, which enable users to run multiple commands in sequence.
Compound commands, which enable script programming and include loops (for repeating a command a specific number of times) and provisional constructs (for running commands simply when a specific condition is met).

Control-line editing is one special fustigate characteristic not ever available with other CLIs. Bash retains a command history, which tin can exist accessed by pressing the up pointer key. This makes it easier to precisely rerun a control. These prior commands can too be modified at the command line, using special keys to re-create, paste, delete or alter a prior command.

Bash is one of the foundations of mod system and network assistants, and new users face a learning curve when using information technology. Yet, in one case learned, bash skills are forever: a time-traveling arrangement administrator from 1992 would likely be able to go right dorsum to work on a modern Linux system, using bash. Learn more near how Fustigate scripting from this tutorial on creating a fustigate shell that accepts arguments when it runs.

This was terminal updated in Dec 2021

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