The Unix operating system has various shells which offer distinct features and better syntax than each other. The two most common shells of the Unix operating system are ash and bash. Both have different usage and functionalities in the operating system and interact with the device in unique forms.
Ash vs Bash
The main difference between Ash and Bash is that Ash is portable while Bash is not the most portable Unix shell. Ash does not provide any additional features like command history while Bash provides additional features like command history.
Ash was launched on 30th May 1989 by Kenneth Almquist. The derivation of the name of the Unix shell was from Almquist Shell. It is also known by other terms like “sh” or “a shell”. The platform on which Ash was launched is cross-platform. It is not a default Unix shell.
On the other hand, Bash was launched on 8th June 1989 by Brain Fox. The derivation of the name of the Unix shell was an acronym of Bourne Again Shell. The platform in which Bash was launched is GNU. It is a default Unix shell.
Comparison Table Between Ash and Bash
| Parameters of Comparison | Ash | Bash |
| Shell’s original name | Almquist Shell | Bourne Again Shell |
| Developers | Ash is developed by Kenneth Almquist | Bash is developed by Brian Fox |
| Scripting type | The shell scripting of Ash is the scripting that can be done in any shell | The Bash scripting is the type of scripting which is particularly done for bash |
| Ease in accessibility | The accessibility is comparatively less easy | The accessibility is quite easy |
| Default shell | Ash is not the default Unix shell | Bash is the default Unix shell |
What is Ash?
Ash is a Unix shell that is lightweight and is originally known as Almquist Shell. It is also known by other names like “a Shell” or “Sh”. The original developer of the Unix shell is Kenneth Almquist. The shell was developed in the late 1980s. The launch of the shell was initially as a clone of System V.4, which was also a variant of the Bourne shell.
The first release of Almquist Shell or Ash is on 30th May in the year 1989. The shell was written in C language. It had an operating system that was Unix- like. The platform on which the shell performed was cross-platform. The initial release of the Unix shell was through a posting to the Usenet newsgroup known as comp.sources.Unix. The moderation and approval were done by Rich Salz.
The description of the Unix shell Ash is given as an implementation of the shell of System V, which had most of the features of that existing shell and also provided additional features to the users. Ash is a virtually compatible, small, and very fast Unix shell with the standard specification of the POSIX.
The initial variants of Ash did not have many vital features like command history mechanism or line editing features. The original developer did not feel that these functionalities could be moved into the driver of the terminal. But the current variants of Ash provide all these features and even more. The original release of ash has also produced Myriad Forks.
What is Bash?
Bash is a type of Unix shell that was designed as free software for the GNU project which could replace the Bourne shell. It is a command language that was originally written by Brian Fox. The launch of the Unix shell was on 8th June in the year 1989. It was released in the version 5.1.16. The preview release version of Bash was in 5.2- alpha.
The usage of Unix shell has been as a default login shell for many Linux distributions. The availability of bash is also like Windows 10 through the windows subsystem design for Linux. The usage as a default user shell of the Unix shell is in Solaris 11. The other applications of Bash as a default shell are observed in the versions of Apple macOS which were released before macOS Catalina of 2019.
The Unix shell bash is written in C language. The operating systems used in the shell are macOS, Unix-like, and Windows. The platform which is used for bash is GNU. It is available in various languages and hence is commonly termed multilingual. Bash is also a command processor since it can run the commands in a text window to cause action.
The reading and execution of commands from a file are also available in bash and the process is known as a shell script. Bash also supports the gobbling of the file name, here documents, iteration, piping, control structures which are used in condition-testing, command substitution as well as variables. There are also a few basic features that are considered to be copied from other Unix shells. Bash also provides the users with numerous extensions.
Main Differences Between Ash and Bash
- Ash is considered predecessor of Bash while Bash is considered successor of Ash.
- The functionality of Ash is very less while the functionality of Bash is comparatively more and can be upgraded.
- Ash does not have any support for job control while Bash has support for job controls.
- Ash is a POSIX shell that is valid while Bash is an invalid POSIX shell.
- Ash is available only in the original language while Bash is available in extended versions of the language
Conclusion
Both the shells of the Unix operating system have different syntax. Ash is written as #! /bin/sh while bash is written as #!/bin/bash. The implementation of both the shells is different from each other. They have different POSIX standards and unique implementations.
The job of both the shell is to interpret the commands and then perform as an intermediary between the operating system in the inner mechanisms and the user. The users should understand every point of distinction between both the Unix shells so that the shells can be operated appropriately in places without any ambiguity.
References
- https://www.sciencedirect.com/science/article/pii/S0960852415012857
- https://www.sciencedirect.com/science/article/pii/S0304389411000677