I had several tests at the beginning of the script. These tests define the “low-level” functions based the capability of the shell. To test new features I “simply” ran all the necessary commands on the test environments (bash, busybox, toybox+mksh).

The script would error out if some necessary capability was missing from the host system. It also had a feature to switch shell if it found a better one (preferring busybox and its internal tools).

Yeah… It was tedious process. It was one of those “I’ll write a simple script. So simple that it’ll work on almost every posixy shell.”… rest is history.

I would then assume those scripts weren’t written properly to begin with.

But yes, shell scripts should be used (normally) to automate some simple tasks (file copying, backups…) or as an wrapper to exec some other program. I’ve written several shell scripts to automate things on my personal machines.

However shell script can be complex program while at the same time being (somewhat) easy to maintain:

• functions, use functions, alot
• • comment every function and describe what it expects in stdin or as an arguments
• • also comment what it outputs or sets

This way at least I don’t break my scripts, when I need to modify a function or some way extend my scripts. Keeping the UNIX philosophy inside shell scripts: let one function do one thing well.

And of course: YMMV. People have wastly different coding standards when it comes to personal little(?) projects.

• utilize awk if you need to process (=more complex than just grepping) large amounts of text.
• • make your awk code conform to at least busybox awk for compability

I once did a sh script that needed (because I wanted a challenge?) to be compatible with vanilla Android shell too. So I needed to test it with regular bash, busybox and mksh+toybox. That was ‘fun’.

I’ve had some initial plans to spllit the code out from that project and develop a “shell” library that would ease building shell scripts that are compatible with different systems… But I bet someone else has already done that.

$() instead of

So much this!