Bash is incredibly useful, and I think more people should use it as a cross-platform default scripting language. That said, for the most compatible shell scripting, learn Bourne shell scripting. https://en.wikipedia.org/wiki/Bourne_shell
It drives me nuts when people say this. /bin/sh is not even Bourne in some distros (dash in Debian for instance), and bash is installed everywhere (unless you're running AIX, I think ksh is still default). There are some bash-isms that are good things and people shouldn't be afraid of. I think it is actually counter productive to tell people to write things in other languages if you need more complexity. If you're writing a script I think you should be weighing instead whether or not you should fully automate what you're doing. If you decide that's the case of course bash isn't going to be your go-to tool, but if you're writing a one-off script what's the point of telling people to use a more robust language if you can do the job with bash?
I don't understand why people are so opposed to bash in general when it's so powerful for how straightforward it is.
Dash is Bourne-compatible! And Bash is not installed everywhere. I can think of at least five systems i've used in the past five years that either didn't have Bash, or Bash was not the default shell, and even the path to Bash isn't the same on all systems (since it is technically an add-on). Anyway, I did not say use Bourne for more complexity, I said for more compatibility.
People are opposed to learning yet another tool. But here's the really funny thing about the "use a more robust language" argument: not only do they introduce more dependencies, they can introduce more bugs (due to increased complexity), and are almost always a maintenance headache. The one thing that's easy to maintain after 10 years is a shell script. Perl is a nightmare to maintain after 10 years (mostly due to the lack of good Perl programmers) and awk is just barely better.
Right I was thinking about that after I replied to your comment, that I let my point get away from me. I read so many other comments putting down bash I was pleading my case to them, not you, haha.
I did not realize dash was bourne compatible. Also, I'm curious what systems you've used didn't have bash installed by default, as I haven't used anything in a long long time that didn't have bash.
Solaris, BSD, HPUX, hell even stripped-down Linux installs (though sometimes it exists and is just in a weird path). Occasionally I need to bootstrap an OS installer and they never have Bash.
By default I write Bourne, and if I need the extra complexity/speed/etc i'll switch to Bash, but it's pretty rare that I need to use Bashisms.
Something else to consider is that many embedded Linux systems do not have bash, only sh (aka Bourne shell). It is often easier to use only Bourne shell-isms to get things to work in a cross-target fashion. That said, I prefer bash for most cross platform (as in cross OS platform) tasks that need a simple shell script of some kind.
I don't understand why people are so opposed to bash in general when it's so powerful for how straightforward it is.