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owner and group look odd

ol muser
ol muser asked
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Last Modified: 2019-07-26
How come sometimes the owner and group for some files look odd on my file system?
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Dr. KlahnPrincipal Software Engineer
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Commented:
This is not un-typical for files brought into the system using tar.  tar stores a file's owner and group as it was stored in the original file system.  So let's say there was a system where user number 20827 was "bill" and his group was "development", group number 3383.  Bill makes a tar copy of a software package, gzips it and uploads it for distribution to users.

But on your system there is probably no user number 20827 and no group number 3383.  tar loads the files into your system with their original owner and group IDs.  Your system has no idea what those numbers correspond to, so it simply displays the numbers instead.

If you find the user number and group numbers annoying, use chown to change them to something which exists on your system.  But be sure to choose something that won't break protections.
David FavorFractional CTO
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Distinguished Expert 2019

Commented:
Could be tar,

Considering the high uid + gid, could also be a removed user.

Could also be a virtual user for a mail system.

Dump out /etc/passwd + /etc/group to see if you have any other close uid or gid numbers. If there are similar ids, then might be a deleted user.

You can look at path of files to determine if this is a virtual user. For example, if this uid/gid owns many Maildir files.
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Commented:
Assuming it's not from a tar , higher numbers like that indicate LDAP joined or AD joined user accounts.  You may have temporarily lost connection to AD or LDAP at the moment of your ls command.   Linux and Unix tend to start at lower numbers unless you actually have that many local users on your systems.

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