This is not wrong, but perhaps some details about different types of errors may be helpful, such as that nonexistent usernames in -U are immediately fatal while an empty result (such as from only nonexistent process IDs in -p or only existing users that do not currently run any process in -U) still writes the header line (if not disabled) and also returns a non-zero exit status.

Closed by commit rS339957: ps(1): Add a standard exit status section (authored by 0mp). · Explain WhyOct 31 2018, 4:10 PM

This revision was automatically updated to reflect the committed changes.

@jilles do you think we could open another PR for your suggestions?

In D17146#366362, @jilles wrote:

This is not wrong, but perhaps some details about different types of errors may be helpful, such as that nonexistent usernames in -U are immediately fatal while an empty result (such as from only nonexistent process IDs in -p or only existing users that do not currently run any process in -U) still writes the header line (if not disabled) and also returns a non-zero exit status.

I've created a PR for this: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=232852

0mp mentioned this in rS358942: MFC r339957:.Mar 13 2020, 9:07 AM

0mp mentioned this in rS358943: MFC r339957:.