Short of tediously cross-referencing man pages, is there a way to determine whether a script contains commands/options that either do not exist or behave differently on BSD systems? (Compared to a GNU/Linux system the script was originally intended for.)

For example, neither OpenBSD find nor FreeBSD find has a printf option. Or for OpenBSD rmdir there is no verbose option (to list removed directories), whilst FreeBSD rmdir has only the shorthand -v, so if a script contains --verbose it must be changed.

ShellCheck could do this with the right rules, but "it's not currently supported and there's quite a few details to be worked out". (I'm not sure what those details might be; given appropriate data it seems straightforward to me.)

Do BSD people currently have any methods for handling this?

The only way I can think of is test for OS:

OS=`uname -s`

But in reality, if you want the script to be portable, avoid all bash specific items and stick to POSIX.

My threads always seem to attract responders who clearly haven't read what I actually wrote. It is very frustrating.

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I expect I will end up having to write something which parses the documentation and/or sourcecode for POSIX/GNU/Busybox/OpenBSD/FreeBSD userland tools to extract a list of commands and supported arguments for each, restructure to a suitable format, then learn enough Haskell to patch ShellCheck with an extra parameter and rule(s) and whatever else is needed.

If I'm lucky maybe someone else will have done that before it next becomes relevant, but I'm not holding my breath.

I totally agree with you, that is annoying. From the other hand I don't think that tool is available, at least I have never heard anything similar. If you want to use it on different hosts you need to make it portable, or you need to make it manage all the differences. At least that's what I made. At the end you will get the answer "if you want the script to be portable, avoid all bash specific items and stick to POSIX."
Or another way to use a common language, which works identically everywhere (perl, python, ...).

I believe using standard 'sh' rather than one with added features would work as it would be POSIX, which all system should be able to use.

Also, use standard tools such as 'sed', 'awk', 'grep', etc, or as above, 'perl'.

1 members found this post helpful.

You should ask your question at the FreeBSD forums.