I agree. I also prefer command line arguments (or even config files) instead of environment variables, in all three cases: when developing software that others

I agree. I also prefer command line arguments (or even config files) instead of environment variables, in all three cases: when developing software that others run, running software that others have developed, and running software I've developed. In addition to what's said in the post, environment variables have one more significant, practical shortcoming: if an application 'foo' takes a FOO_LOGDIR (which defaults to /var/log/foo if unset) and you accidentally slip it a FOO_LODGIR=/run/log/foo - it will silently accept and ignore it, while you will be scratching your head why is the logging not behaving as expected, until you discover the typo. Naturally, 'foo' could ensure no FOO_* with unknown names are set. But I've yet to see an application like this in practice, while nearly every single flag parsing library out there immediately errors out on unknown flags.