[stephenr]

Bash is known to have version/compatibility issues - Homebrew reports Bash 4.3, but Ubuntu only has 4.3 available for the most recent version - anything from before April will only get 4.2.

This is my whole point - targeting /bin/sh means targeting a POSIX compliant shell, which may be implemented by any number of different codebases, with a defined standard to meet. Posix mode in Bash 4.3 should be the same as Posix mode in Bash 3.9, etc. - targeting /bin/bash means targeting whatever specific bash oddities come with the version installed.

[eropple]

That's a fair point for bash ultra-power users. It doesn't really reflect on my use case. I don't exactly pull out all the stops. I use [[ ]] and set -e, which have very familiar semantics that haven't changed for a long time, and that's about it. I am very confident in my selection of "portable bash"-isms as far back as 3.2 (running 4.x on OS X has only come on recent, I added it a couple months ago).

Don't get me wrong: I could use /bin/sh. But I would have to write worse code to do it. I'll take the possibility of a bash regression over writing all my shell scripts in sh.