File owner is a number

[C_V]

Hey guys it is my understanding that when i file is owned by a numerical value the user has been deleted in the system. I check 1 particular file and its owned by 0 in which it is root as per the /etc/passwd the root uid is 0. then i saw other files in which the owner is 50 but i cant find any user with uid of 50. Any thoughts about this?

[Andres_13 · Accepted solution]

Hi, could you post an example, maybe ll output?

Regards!

[Patrick Wallek]

If the file has a number as an owner, then that is/was the UID of the user that own(s/ed) the file.

It is the UID and GID that is stored by the system to keep track of the owner and group of files. Commands like 'ls' use /etc/passwd and /etc/group to 'map' UID/GID to actual user and group names.

There are 2 cases that can cause you to see something like this:

1) The user has been deleted from the system. In this case the 'ls' command has no map (no entry in /etc/passwd) to correlate a UID to an actual user name.

2) If the permissions of the /etc/passwd file are too restrictive (if it is not readable by all, ie. at least 444 permissions) then a user may not have rights to read the file. In this case the user will see the UID as the owner for ALL files.

[Dennis Handly]

>but i cant find any user with uid of 50.

As mentioned, there are several ways this could happen.
1) User deleted. (Patrick)
2) You have installed numeric user/group names
3) Your NIS is bonkers.
4) pwgrd(1M) is broken?
5) Permission problems (Patrick)

You may fix 3) by:
/sbin/init.d/nis.client stop
/sbin/init.d/nis.client start

[Bill Hassell]

The reality is that all files are owned by numbers. That is all HP-UX needs for opwner and group. But to make things a bit more friendly, the passwd and group files translate the number into a name. You can create a file and assign it any number (within the owner/group limits) like this:

chown 1234:5678 myfile

In 'normal' operations, ownership is usually assigned using names (user and group), so possibly in the past, there was a user with an ID of 50, but the user was removed or the user's ID was changed (not a good idea but certainly can be done).

Now you said that you saw a file with an owner of 0 (I am assuming you are using ls -l). Since root must exist on a stable Unix system, if you see 0, then either root's user ID has been modified in /etc/passwd (big oops) or /etc/passwd has been 'protected' by removing read capability (a very bad idea). /etc/passwd and /etc/group must always be readable by everyone.

[Analyst]

Hi Nakihid,

>File owner is number.

As the previous writers ,mentioned.

When the user is deleted it retains with the UID, for tracking purpose.

Check the /etc/passwd entries , whether any changes happened.

check for any user modification/deletion.

see the example :-
drwxr-xr-x 2 500 test 96 Dec 3 06:53 user
-rw-r--r-- 1 500 test 0 Dec 3 06:53 ppp

Thanks,
Analyst.

[Venkatesh BL]

One more possiblity: Even if you have changed the user id of a user, the file will contain the old userid only.

Ex:-

OLD: (uid of c2user1 = 7569)
-rw-rw-rw- 1 c2user1 c2grp 0 Dec 3 08:45 aaaa



NEW:
-rw-rw-rw- 1 7569 c2grp 0 Dec 3 08:45 aaaa

As you can see, the uid on the file still refers to the old one.

[Jozef_Novak]

Hello,

this can also happen if the file was copied over from another system and the user that owned the file on the original system does not exist on the new one. In this case, the hint would be obvious, just create the user on the new system as well.

Jozef

[C_V]

Thanks for the replies guys!:)

[Steven Schweda]

> [...] all files are owned by numbers.

Exactly.

> As you can see, the uid on the file still
> refers to the old one.

Of course it does. The file owner is a
number, and you change that number, for that
file, using chown. Changing which user name
(if any) is associated with that number has
no effect on any file's owner (number).

[Venkatesh BL]

Sigfred Nakihid
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