Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

On Debian and Ubuntu (probably on other GNU systems too), when ps lists a process' user, it normally resolves its name, but when a process is running as a user which has a dash in its name, the user's numeric ID is shown instead. I think this is very annoying.

Is there a reason for this behavior or is this a bug and needs to be reported?

share|improve this question
I can't say I've ever noticed this, are you talking about the UID column ? – Iain Apr 13 '12 at 11:38
@lain yes, for example in ps au or ps -ef – aef Apr 13 '12 at 11:53
I don't see this. For example: www-data 20183 27367 0 Feb28 ? 00:02:45 nginx: worker process www-data 20184 27367 0 Feb28 ? 00:02:58 nginx: worker process www-data 20185 27367 0 Feb28 ? 00:02:50 nginx: worker process www-data 20186 27367 0 Feb28 ? 00:02:48 nginx: worker process – cjc Apr 13 '12 at 11:54
Do you have some weird alias or format option set? – cjc Apr 13 '12 at 11:55
up vote 4 down vote accepted

"ps" displays the UID number if the user name is too long for the display, On Debian systems which include the "Debian-exim" user it is common to see this as the UID instead. This is probably what you're seeing. The presence of a '-' is a red herring here, and it happens everywhere that uses procps, not just Debian and Ubuntu:

"Why do long usernames get printed as numbers?"

share|improve this answer
This had actually nothing to do with the dashes but with the length of the user names. Thanks for the information. – aef Aug 7 '12 at 13:51

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.