Run part of a bash script as a different user

Question

Is there a way to make part of a script run as a different (non-root) user? If it helps , the part to be run as a different user occurs at the end of the script

Edit :
OS -> Ubuntu 9.04

possible duplicate of [Howto switch / chage user id witin a bash script to execute commands in the same script?](http://superuser.com/questions/468161/howto-switch-chage-user-id-witin-a-bash-script-to-execute-commands-in-the-same) — Dan Dascalescu, Jul 11 '14 at 10:35

score 57 · Accepted Answer · edited Apr 13 '17 at 12:14

57

Use the sudo command in the script.

In the form:

sudo -u username command

the sudo command runs command as the user username.

If the script is being run as root, I don't think it will prompt for a password. Otherwise, this article discusses how to use sudo with password in one command line?, and this article discusses how to use sudo without password?

edited Apr 13 '17 at 12:14

Community

1

answered Jan 09 '10 at 04:53

pcapademic

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This is nice and easy, but is there a way to do this for a group of commands instead of one at a time? – Andrew Dec 05 '13 at 23:08
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write a bash script, make it executable `chmod +x script.sh` and then just `sudo -u username script.sh` – 55651909-089b-4e04-9408-47c5bf Jun 11 '14 at 15:05
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@Andrew I was wondering this myself and the following worked for me: sudo -u ic sh -c 'cmd1 && cmd2' – Karussell May 29 '17 at 14:26
Also include the `i` option if you want to acquire the user's environment – neoDev Nov 21 '17 at 06:17

AXE Labs · Answer 2 · 2013-03-29T15:58:29.417

12

# I=like:

#test if running bash as a different user works
sudo -u nobody bash -c : && RUNAS="sudo -u nobody"

echo 1: $USER

#Runs bash with commands between '_' as nobody if possible
$RUNAS bash<<_
echo 2: \$USER
_

echo 3: $USER

# ./run

1: root
2: nobody
3: root

edited Mar 29 '13 at 15:58

answered Mar 28 '13 at 18:38

AXE Labs

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Could you add some explanatory text? – Kazark Mar 28 '13 at 19:21
Manish explains in the suggested edit: https://superuser.com/review/suggested-edits/1095251 – AXE Labs Dec 22 '21 at 18:39
Use '_' instead of _ to expand the variables within – Rein F Oct 05 '22 at 02:28

score 8 · Answer 3 · edited Mar 20 '17 at 10:17

8

This answer is good, but the serverfault advice is slightly dangerous - would allow anyone to run anything as root! So I'm posting here because I can't format the comment.

I would recommend using visudo to give the permissions you need as precisely as you can. Type visudo and add a line like:

username hostname = NOPASSWD: /full/path/to/command1, full/path/to/command2

If you do need to run this same thing on many hosts, you could open it up with:

username ALL = NOPASSWD: /full/path/to/command1, full/path/to/command2

But I would **not* use either:

username ALL=(ALL) NOPASSWD: ALL

or username hostname = ALL

The sudoer man page has lots of gory details

edited Mar 20 '17 at 10:17

Community

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answered Jan 09 '10 at 06:33

DaveParillo

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Would it work for a command available to a particular user only ? – Manish Mathai Jan 09 '10 at 09:42
You can specify that only particular users can run the command (in the examples above, replace `username` with the username who should be able to run the command). If the executable you want to run is only executable by one particular user, that's fine too - just pass that username in the `sudo -u username commandline` line of the script. – James Polley Jan 09 '10 at 10:31
@Manish. Yes. What the sudoers file says is "Allow this username on this host to run command1 without having to provide a password. – DaveParillo Jan 09 '10 at 17:23

score 4 · Answer 4 · edited Jan 06 '19 at 04:07

4

For sonarqube:

sudo -u sonar /usr/bin/sonar start

where sonar is the name of user used to run the command /usr/bin/sonar start

edited Jan 06 '19 at 04:07

Community

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answered Oct 08 '13 at 07:53

burtsevyg

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score 4 · Answer 5 · answered Nov 29 '13 at 14:07

This way, end of a script will be executed by different user (root). Please note the $[LINENO+2] and exit $? calls. These are required to make the end of the script to execute just once and to preserve the exit code of the sudo call.

#!/bin/bash                                                                                                                                                                                                                                  
echo $USER                                                                                                                                                                                                                                      

# pipe the rest of this script via a sudo call                                                                                                                                                                                                                                         
tail -n +$[LINENO+2] $0 | exec sudo bash                                                                                                                                                                                                     
exit $?                                                                                                                                                                                                                                     
echo $USER
exit 1

score 2 · Answer 6 · answered Jan 09 '10 at 21:37

2

not so sure about it, but if you want that ONLY the end of that script will run as a different user, you could add su someuser before the end of the script.

Am I missing something?

Hope that helps,

Regards

answered Jan 09 '10 at 21:37

dag729

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I think this is the most appropriate answer, having all other answers suggesting sudo, which is often not installed by default on some minimal linux installations. – Tim Jan 07 '18 at 03:04
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`su someuser` will start a new shell, it won't execute the rest of the script. – Just a student Feb 14 '20 at 15:43
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Yeah this won't work, it'll just go into a new shell then do nothing forever, the rest of the script won't be executed – Shardj Jan 25 '22 at 12:43

Run part of a bash script as a different user

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