bash vs csh vs others - which is better for application maintenance?

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What Linux shell should I use?

I am starting to get proficient in a Linux environment and i'm trying to pick a weapon of choice in terms of command shell scripting (as i'm still a big n00b at this) that will help me (and others) manage, test and administer a set of server side applications running on a *NIX environment.

My question is: What is(are) the preferred command shell(s) out there when the following criteria are considered:

1. How easy is it to learn/understand for a junior dev who has never had an exposure to shell scripting?

2. Is there a big pool of developers out there that know this shell script?

3. Is it safe and easy to use - will script errors be silent or give intelligent error output, will it let the uninitiated shoot them selves in the foot?

4. How portable is it? - Can i expect the same script to run in OpenSolaris as well as Redhat, FreeBSD? (granted command syntax and options for specific OS will change accordingly)

5. How standard is it? Is it expected to be included on most distro's of *NIX or does it have to be installed additionally?

I understand that there are camps out there who hold strong feelings for/against specific command shells, i am just looking for an informed opinion.

Answer 1

These days, just about any non-embedded (or large embedded) operating system has a POSIX:2001 a.k.a. Single Unix v3 compatibility layer. This is native on unix platforms (Linux, Mac OS X, Solaris, *BSD, etc.) and installable on other platforms such as Windows and Android. POSIX specifies a shell language, usually known as POSIX sh. This language is derived from the Bourne shell.

Most unix systems have one of two implementations of POSIX sh: ksh or bash, which have additional useful features compared to POSIX. However some less mainstream systems (especially embedded ones) may have only POSIX-mandated features.

Given your objectives, I see three choices:

• Restrict yourself to POSIX sh. Pro: you don't have to worry about differing variants, since there's a standard and compliant implementations are readily available. Con: you don't benefit from bash and ksh's extensions.
• Use the intersection of ksh and bash. This is attractive in appearance, but it does mean you have to use two reference documents instead of just one — and even the features that bash and ksh have in common don't always use the same syntax. Figuring out which one you want to use on a given system is also a pain.
• Choose one of ksh or bash. Both bash and ksh are available on all unix-like platforms and on Windows. Both have an open source implementation (the only one for bash, ATT ksh93 for ksh) that can be installed on most platforms. I'd go for bash over ksh for two reasons. First, it's the default on Linux, so you'll find more people who're used to it. Second, there are systems that come with an older, less-featured implementation of ksh; even if you can install ksh93, it's another thing you have to think about when deploying.

Forget about csh for scripting, and forget about zsh if you want common default availability.

See also What are the fundamental differences between the mainstream *NIX shells?, particularly the “for scripting” part of my answer.

Note that shell programming involves other utilities beyond the shell. POSIX specifies those other utilities. “Bash plus other POSIX utilities” is a reasonable choice, distinct from “POSIX utilities (including sh)”.