On: Defensive BASH programming

[jakub_g]

Slightly off-topic but maybe some people will find it useful:

I used to write my various glue-things-together scripts in bash, but this quickly becomes a nightmare as the script grows, due to bash's corner cases, syntax, portability issues etc.

Recently I wrote my massive glue-things-together script with nodejs (since I already use node for many things) and it's much more maintainable and I couldn't be more happy. Node 0.12 has execSync which was the missing piece for making node the proper shell scripting platform.

If you are interested, you may want to check shelljs [1] and my snippets for robust `exec()` and `cd()` in node.

[1] https://github.com/shelljs/shelljs [2] https://gist.github.com/jakub-g/a128174fc135eb773631

[vacri → jakub_g]

Is it really a 'script' if you need to add a dir full of modules? I've always thought of 'scripts' as all-in-ones.

[jakub_g → vacri]

Well, you're right, it's a tradeoff. The 'script' is not standalone anymore, but it's a (script + package.json) and needs `npm install` to work properly. I still use bash for simple things, but if it grows too much and logic starts getting non-trivial, IMO it's a valid use case to switch.

[z3t4 → jakub_g]

I would love to write my bash scripts in node, but end up writing them in bash anyway ... How do you do something like this in node?

  sudo -u 2>&1 >> logfile | tee | echo

[grhmc → z3t4]

I'm assuming this isn't a real example of a thing you would want to do, because it doesn't make sense. (redirecting stderr to stdout, stdout to a file, then pipe to tee and echo?)

At any rate, you'd:

1. use some sort of popen()

2. use pipes and pass the same pipe to stdout as stderr

3. pass stdout of one popen to another's stdin

4. just use bash, because this gets so hairy and bash does it really well. When I want to use a complex pipeline of programs in non-bash programs, I'll frequently popen() to a bash script. This is ugly, but if you're really careful (shellshock?) it can be ok.