Good info for writing bash scripts that are large enough to need debugging, but why would one do that in the first place? Python or Perl would be better choices at that point.
When you are fundamentally running shell commands, using python/perl really don't make a lot of sense. Use the best tool for the job. Note that for my dayjob I write python almost fulltime, but if I'm almost exclusively running shell commands, I'll write a shell script. Just because you can do something one way doesn't necessarily mean I should.
See I'm of the opinion that if you need arrays and associative arrays, bash is the wrong tool for the job. If you have a recent bash it has both of those, just seems wrong in such a clunky language with awful scoping.
I write a lot of bash scripts, but lately I've been doing most of my shell interop in Ruby instead. Backticks are pretty good and I can munge things in easier ways than bash or Python. And with `ruby -n`, the script is invoked line-by-line--perfect for processing piped content.
Use the best tool for the job. If you don't know bash/bourne shell well, use ruby/perl/python/etc. I started out as a sysadmin years ago and know bourne shell/bash very very well. It is all about what works best for the problem.
Sure. And don't get me wrong, I write a lot of bash scripts. =) I think any logic beyond string replacement is probably edging out of where it's a good idea, if only because other people then have to read my stuff later, but it's totally fine for that. I'm saying more that I think Ruby (or Perl) make more sense than Python given the tools it provides.
Bash is not just Bash but also sed, awk and all the other goodies. You can grow Bash scripts from the command line. You don’t have to worry about things, everything is a string is a number is a stream. One could go so far as to argue that shell pipes behave quite distinctly functional-programming-ly(?).
Plus it’s some sort of middle ground between “BDFL tells you to put a space there“ and “one day, archaeologists will find a script written in Perl, awk and csh and it will become the new millenium’s Rosetta stone“.
It's happened more than once that I've started something in bash, thinking it's a small enough job, only to see it growing in time - a lot. Sure, in theory you could rewrite it in Python, but you don't always have that luxury in practice.
Bottom line is - keep bash scripts small, but be prepared to deal with the cases when they grow like Jack's magic beanstalk.
