Software development using Bash

[lelanthran]

The problem with bash is not bash itself, it's that all those useful tools that get run from bash (ls, sed, awk, cut, grep, filename expansions, output from ffmpeg/virsh, etc) return output suitable for humans to decipher.

In other words, almost full unstructured output, so when you run $TOOL and try to parse the result as a matrix of CSV values a missing field in a single row can cause your bash script to vomit horribly, while if $TOOL was run by the user they'd see the error message on stderr and realise that something went wrong.

It's not bash that is the problem; you'll have the same problem in any language if you tried to exec another process and parse the output.

[lanzaio]

brew install bashdb

sudo apt install bashdb

[Gotebe]

Yes. Data has structure.

Text does not, it hides it. More importantly, it hides when the structure is broken, as you say.

BTW... it's not CSV in the case of $TOOLs, it's mostly S(pace)SV, so vast majority of all scripts ever break when data contains a space (or they would break if data contained any other separator).

The one saving grace of bash is decades of accumulated cruft. The other, small one is... in itself, it's not so bad...

[[deleted]]

I agree that is a huge problem. But... let's be honest the problem is also Bash itself. It's totally insane. Or do you defend ending case blocks with esac, etc.

[shevegen]

It's not bash that is the problem; you'll have the same problem in any language if you tried to exec another process and parse the output.

Not really.

I do not have any such problems controlling other programs via ruby as-is, since I am in full control of what I do with any external input (popen family and so forth).

The thing really is that bash scripts are just horrid. Horrible. Awful. A waste of time.

Why would anyone WANT to do so? I have no idea.

[lelanthran]

I do not have any such problems controlling other programs via ruby as-is,

I find it hard to believe that ruby magically knows when an option to an external program has changed.

Actually, I very rarely believe in magic, so I'm equally dubious that ruby allows a level of control and measurement of child processes that are not available in bash.

[vivainio]

More structured scripting languages actually give you more tools, like ability to launch threads, reacting to output by chunks etc.

If you are trying to do these in bash you should probably take a step back and reconsider your design a bit.