Take "ps", for example. The BSD "ps" program is fundamentally different to the Linux "ps" program. It's also, quite importantly, different to what the Linux "ps" manual erroneously claims the BSD "ps" to be.
* https://manpages.debian.org/testing/procps/ps.1.en.html
* http://man.openbsd.org/ps
* http://netbsd.gw.com/cgi-bin/man-cgi?ps
* https://freebsd.org/cgi/man.cgi?query=ps
* https://unix.stackexchange.com/a/511530/5132
Take "ps", for example. The BSD "ps" program is fundamentally different to the Linux "ps" program. It's also, quite importantly, different to what the Linux "ps" manual erroneously claims the BSD "ps" to be.
* https://manpages.debian.org/testing/procps/ps.1.en.html
* http://man.openbsd.org/ps
* http://netbsd.gw.com/cgi-bin/man-cgi?ps
* https://freebsd.org/cgi/man.cgi?query=ps
* https://unix.stackexchange.com/a/511530/5132