Linux – Should I use `sudo` or `su` in a startup script

linuxsusudosysvinit

I have a personal program, that has a server/client design.

The server daemon part of it, should be run as its own limited user, and the program was not designed to drop its root privileges (if started as root) like some Linux programs do.

So my question, in its startup script in /etc/init.d/, should I use sudo or su to run this daemon as another user? Does it make a difference? Will either of the two even work? Something else?

The operating system is a custom GNU/Linux one, built using "Linux From Scratch" instructions, and does have both programs running correctly.

Best Answer

If you can easily alter the program so that it drops its privileges, then this is the best approach. Switching user ID in the startup scripts is kludgey and rather inflexible, even if it does "work".

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I run sudo directly from the script:

if [ $EUID != 0 ]; then
    sudo "$0" "$@"
    exit $?
fi

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Where is this information stored?

It's probably under /var/db/sudo or /var/run/sudo and you'll probably find directories of usernames with files under them ordered by tty number.

The actual privileges granted, including how long the sessions lasts before you have to enter your password again depends on how sudoers is setup. There's settings to grant/restrict a lot of different things, but those aren't stored in these files which only store timestamps. How long a session lasts, or when sudo needs to prompt for your password again, is determined by a delta of current time and the session timestamp in this directory, and how long sudo is setup to allow a session to last.

Best Answer

Related Solutions

Bash – Prompt for Sudo Password and Programmatically Elevate Privilege in Bash Script

Linux – How does sudo remember you already entered root’s password

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