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What does UID root and GID root mean?


Please give me some examples...


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Are you refering to "setuid root" and "setgid root" ? – Mei Jun 1 '10 at 21:48
up vote 7 down vote accepted

UID stands for user ID, and GID stands for group ID. They are numeric identifiers associated by a UNIX or Linux system with an user or group account, respectively (e.g. 0 or 5160). Systems also use human-readable users and groups for convenience (e.g. root or adm).

Users represent an individual person or role, whereas groups represent a collection of people or roles. Each is used by the system to manage who gets access to resources like files, processes, etc.

On many systems, you'll find that users and groups (confusingly) might be named the same thing, even though they have different functions. Also, some people (confusingly) use UID or GID to mean the same as user or group instead of the numeric IDs. You can find all the names and IDs, and how they are mapped to each other in files like /etc/passwd and /etc/group which you can read about in the appropriate man pages.

So, "UID root" (mistakenly) means the root user, and "GID root" (mistakenly) means the root group.

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UID root says the file is owned and fully controlled by the user root. GID root says that members of the group root can control the file as per the group permissions.

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It could also be the user httpd is impersonating, just going on the question's tags. – Chris S Jun 1 '10 at 20:24

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