Ubuntu – Run a shell script as another user that has no password

bashcommand linesudo

I would like to run a script from the main ubuntu shell as a different user that has no password.

I have full sudo privileges, so I tried this:

sudo su -c "Your command right here" -s /bin/sh otheruser

Then I have to enter my password, but I am not sure if that script is now really running under that user.

How can I confirm that the script is really running under that user now?

Best Answer

  • You can do that with su or sudo, no need for both.

    sudo -H -u otheruser bash -c 'echo "I am $USER, with uid $UID"' 
    

    The relevant parts of man sudo:

    -H   The -H (HOME) option requests that the security policy set
         the HOME environment variable to the home directory of the
         target user (root by default) as specified by the password
         database.  Depending on the policy, this may be the default
         behavior.
    
    -u user     The -u (user) option causes sudo to run the specified
          command as a user other than root.  To specify a uid
          instead of a user name, use #uid.  When running commands as
          a uid, many shells require that the '#' be escaped with a
          backslash ('\').  Security policies may restrict uids to
          those listed in the password database.  The sudoers policy
          allows uids that are not in the password database as long
          as the targetpw option is not set.  Other security policies
          may not support this.
    

    su can only switch user without providing a password if you are root. See Caleb's answer

    You can modify the /etc/pam.d/su file to allow su without password. See this answer.

    If you modified your auth file to the following, any user that was part of group somegroup could su to otheruser without a password.

    auth       sufficient pam_rootok.so
    auth       [success=ignore default=1] pam_succeed_if.so user = otheruser
    auth       sufficient   pam_succeed_if.so use_uid user ingroup somegroup
    

    Then test from terminal

    rubo77@local$ su otheruser -c 'echo "hello from $USER"'
    hello from otheruser