I need a linux user (lets call him "bob") who is allowed to run a list of commands which require root privileges. So let him be required to run /sbin/firstcommand and /sbin/secondcommand (which are part of the infamous bob-daemon¹) as root, as in sudo firstcommand. Without having to input a password.

This is what I've done to /etc/sudoers so far:

Cmnd_Alias BOBCOMMANDS = /sbin/firstcommand, /sbin/secondcommand

This leads to bob$ sudo firstcommand and bob$ sudo secondcommand successfully be run as root, but leaves no way to run i.e. bob$ sudo mount ... ..., even with providing a password, which feels perfect to me.

Now, I want the aforementioned bob-daemon¹ to run as user bob rather than root, because it only needs those privileges for the BOBCOMMANDS. In fact, whenever the bob$ firstcommand is issued, I want bob$ sudo firstcommand to be executed.

Looked to me like an alias could fix this: bob$ alias firstcommand="sudo firstcommand"; alias secondcommand="sudo secondcommand" actually worked, but I failed to make the aliases persistent without bob having a home directory.

The last thing I should mention is that this should be easily deployable to multiple machines, so I would prefer not to touch linux' existing system files, apart from having to create bob and changing sudoers.

Any solutions?

¹ simplified by me

  • How you start the daemon; with systemd ? or is it possible to set it up with systemd units? – Maze Mar 3 at 19:57

If this is for a daemon, the standard way of doing things is to put something like this in the init script file:

su -c '/command/to/start/actual/daemon' "$USER"

In the script file that should be run as bob, just put sudo in front of the pertinent commands.

Also, make sure you read this about enabling alias expansion in non-interactive Bash shells (e.g. the ones started by a script or daemon).

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  • Actually, the daemon handles user switching itself - started up as root, it does some bootstraps before forking and continuing to run as bob. Plus, I did not create the daemon and would like to avoid patching it for the sake of updatability … – LDericher Oct 28 '14 at 12:07

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