sudo for single command in bash script

Question

This may be a stupid question.

I have a script that I want to be portable between Mac OS X and a Linux box I use. In OS X, a command in the script requires sudo, where on the Linux box, it does not.

Long story short, how does one run one command in a script with sudo, while then removing the elevated privileges for the rest of the script?

I have tried to use

su -

and

su -c

but they both seem to error out. (They say "sorry" and move on, I assume because it is trying to run as root and root does not have a password).

I know there has to be a silly and easy way to do this, what does everyone suggest?

Mild Fuzz · Accepted Answer · 2013-06-14 10:22:09Z

7

You can 'revoke' the sudo permission (actually: close the sudo time window early) by doing:

sudo -k

Also, you can configure sudo to only allow elevated permissions on certain commands, or even to impersonate non-root for specific commands. See man sudoers. The examples section makes it exceedingly clear that there is virtually no limit to the configurability of sudo (roles, hosts, commands, allow escaping, allow sudo target users, exceptions to allowed things, password less authorization etc etc).

Hopefully an interesting example in your context:

The user fred can run commands as any user in the DB Runas_Alias (oracle or sybase) without giving a password.
   fred           ALL = (DB) NOPASSWD: ALL

If you can't / don't really want to meddle with /etc/sudoers (visudo!) then I suggest using something like

{
     trap "sudo -k" EXIT INT QUIT TERM
     sudo ls # whatever
}

edited Jun 14, 2013 at 10:22

Mild Fuzz

31.3k34 gold badges106 silver badges152 bronze badges

answered May 7, 2011 at 9:35

sehe

400k49 gold badges475 silver badges673 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

rick Over a year ago

this was exactly what i needed. run the command, then run sudo -k. thanks very much.

Adam Rosenfield · Accepted Answer · 2011-05-07 04:32:33Z

0

Try sudo su instead of su to change back to a regular user.

answered May 7, 2011 at 4:32

Adam Rosenfield

402k102 gold badges524 silver badges600 bronze badges

2 Comments

rick Over a year ago

when i try "sudo su umount /dev/disk1", i get "su: unknown login: umount". looking through man sudo, i can only conclude it is looking for a user named "umount"?

Adam Rosenfield Over a year ago

@rick: Yes, it's looking for a user named umount. su is for changing to a different user (usually root) and can only be run as root, so the argument that it takes is a username. sudo is for running one single command as a different user. In your example, you're saying you want to run the command su umount /dev/disk1 as root, which then says you want to change to the user umount (with an extra ignored argument).

Gordon Davisson · Accepted Answer · 2011-05-07 15:05:59Z

0

Use sudo without su:

#!/bin/bash
whoami  # Runs under your regular account
sudo whoami  # Runs as root
whoami  # Runs under your regular account again

Here's the output when I run it:

$ ./sudotest
gordon
Password:
root
gordon

answered May 7, 2011 at 15:05

Gordon Davisson

128k16 gold badges141 silver badges168 bronze badges

Collectives™ on Stack Overflow

sudo for single command in bash script

3 Answers 3

1 Comment

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related