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.