116

All I need to do is to run a specific script as a particular user who does have the nologin/false shell indicated in /etc/passwd.

I would run the script as root and this should run as another user. Running:

~# su -c "/bin/touch /tmp/test" testuser

would work, but I need a valid shell for the testuser. I know I can disable the password with passwd -d testuser and leave the shell to /bin/bash this way would secure a little bit but I need to have nologin/false shell.

Basically what I need is what crontab does when we set jobs to be running as a particular user, regardless this one has nologin/false shell.

p.s I found this thread Executing a command as a nologin user, but I have no idea how to concatenate the command su -s /bin/sh $user to the script I need to run.

ivanleoncz
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Tommaso
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8 Answers8

153

You can use the -s switch to su to run a particular shell

su -s /bin/bash -c '/path/to/your/script' testuser

(Prepend sudo to the above if testuser is a passwordless user.)

Dominic Cronin
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user9517
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  • What if su is root:root -rwsr-x--- ? – Patryk Mar 10 '15 at 00:24
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    What if the user doesn't have a password? – CMCDragonkai May 18 '15 at 10:12
  • @CMCDragonkai That is left as an exercise for the student. – Wesley May 18 '15 at 18:41
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    @Wesley Found out that you need to be root to run that command for passwordless user. – CMCDragonkai Aug 16 '15 at 10:53
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    @lain, If the user is supposed to not have a shell, the process related to the command should not be a child of a bash process. Thus, you should also use exec to replace the shell with the script. And if you like to make the script a child of init, you just use &, as an example su -s /bin/bash -c 'exec /path/to/your/script &' test – Facundo Victor Apr 27 '16 at 12:59
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    Since I have spent last 20 minutes working out how to achieve the same result using runuser, I'd like to point out that su -s SHELL parameter renders runuser command pretty much useless :) Thanks Jan! – Jiri Jul 21 '16 at 18:06
  • @CMCDragonkai use sudo: sudo su -s ... – Calimo Dec 12 '16 at 12:45
  • If called from root, runuser is preferable. It is compatible whith su. – user3132194 Mar 12 '18 at 11:30
  • Anyone know the mac way to do this? -s isn't an option – Ray Foss Jul 19 '18 at 14:29
  • Just as a reminder, for me and others who work with Zabbix: this example is EXTREMELY USEFUL, when it comes to commands that require sudo permissions. Example: if you provide access to nginx -t to zabbix user via sudoers, and want to test the command sudo /usr/sbin/nginx -t. You can run su -s /bin/bash -c 'sudo /usr/sbin/nginx -t' zabbix, even when zabbix user has nologin as shell. – ivanleoncz May 26 '20 at 00:28
16

You can do this with sudo -u if you have it installed:

# whoami
root
# sudo -u apache whoami
apache
# getent passwd apache
apache:x:48:48:Apache:/var/www:/sbin/nologin
Handyman5
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  • How do you pass parameters to sudo -u apache whoami? – CMCDragonkai May 18 '15 at 10:11
  • @CMCDragonkai Any parameters after the command will be passed along. You can think of it like "sudo [-u apache] [whoami ]". – Handyman5 May 19 '15 at 06:27
  • I think using sudo -u is probably not a good idea for running commands as a nologin user, because it exposes the SUDO_USER in the environment who is the real one invokes the command. Maybe I am just overthinking it. – Meow Apr 30 '16 at 15:36
8

By providing the script as the argument to execute to /bin/sh:

su -s "/bin/sh /your/script/location" username
adaptr
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2

just realized :

su -s "/bin/bash" -c "/bin/touch /tmp/testuser" testuser

maybe there is a better way ?!

Tommaso
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2

actually, the best way to do this is via runuser

see the man page for details

this tool is used to deal with the situation as the developer said in his bolg

Whenever an service is running as root and wants to change UID using the shell it should use runuser.

http://danwalsh.livejournal.com/55588.html

i've post this answer in many palaces, forgive me if you find this annoying

Community
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Y00
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    Please do not post link-only answers to prevent link rot. Instead, add the most relevant information from the link to your answer or alternatively, post the link as a comment instead of an answer. See this http://serverfault.com/help/how-to-answer help center article for further information. – Federico Galli Feb 16 '18 at 10:01
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    @FedericoGalli the most relevant information is already added, there is no need to copy and paste the usage, the man page provides enough information – Y00 Feb 20 '18 at 08:27
-1

All you need is sudo:

sudo -u <user> -g <group> -- <command>

Michael Böckling
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-1

Use sudo -u to specify the user. Also use the -i flag to set environment variables of the target user too.

sudo -i -u user command
Wayne Shelley
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-2

Use su command with shell -s and -c command. As shown below

 su  exec -l -c '/bin/bash /etc/update_conf.sh' -s /bin/bash
chetan
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