topic Re: Set User Id in Operating System - Linux

Set User Id

Abhirama.M.V — Fri, 28 Dec 2007 05:21:07 GMT

hi,
please anyone can tell me about set user id.
How it works & what's the use of it?

Thanx in advance
Abhirama

Re: Set User Id

Stuart Browne — Fri, 28 Dec 2007 11:50:31 GMT

It really depends on what you're wanting to set the user id of.

If you're wanting to create a user with a specific UID, then 'useradd -u ' will create it.

If you want to launch a process as a given user, depending on the process, you can just 'su - -c '.

If it's a daemon process however (such as squid or apache), there's usually daemon configuration values which say which user they drop their privileges to ('cache_effective_user' and 'User' respectivly in these two cases).

If this isn't what you're after, more details please.

Re: Set User Id

Ivan Ferreira — Fri, 28 Dec 2007 15:32:17 GMT

If you talk about SUID bit, "chmod u+s", this means that a program will run with the privileges of the owner of the file instead of the user who runs the program.

For example, if /bin/rm is owned by root, without SUID bit, if user1 runs the command /bin/rm -fr /root, it will run as user1, and he won't be able to delete the files in /root as user1 has no permissions.

If /bin/rm is owned by root, and it has SUID bit enabled, if user1 runs the command /bin/rm -fr /root, it will run as "root" (the owner of the program), and will be able to delete the /root directory.

Re: Set User Id

skt_skt — Fri, 28 Dec 2007 18:42:57 GMT

What Ivan said sounds reflecing to your needs. Please explain your scenario.

Re: Set User Id

palaniappan.sp — Tue, 01 Jan 2008 11:51:37 GMT

Hi,

I hope this link will be helpful...
http://www.codecoffee.com/tipsforlinux/articles/028.html

Regds
Palani