Switch to other user instead root while using sudo

You can't easily do what you ask (i.e. make sudo startup.sh run as a named non-root user). What you can do, though, is one or both of the following

1. Tell users to use sudo -u tomcat /path/to/startup.sh instead of sudo /path/to/startup.sh, and disallow the latter anyway

   Add this line to your sudoers (remember visudo) such that tomcat here is the target user account. Change the first ALL to a list of users if there are only certain people allowed to run the script as the target user

    ALL ALL=(tomcat) /path/to/startup.sh 

2. Make the script perform the sudo, and disallow sudo -u root for the script. You'll need #1 (above). Ensure that tomcat here matches the tomcat in sudoers.

    #!/bin/bash # targetUser=tomcat if [[ $UID -ne "$(id -u "$targetUser")" ]] then exec sudo -u "$targetUser" "$0" "$@" exit 1 fi # ...script continues but as the $targetUser... 

   This allows people to run /path/to/startup.sh (or even just startup.sh if it's in the $PATH) and not worry about the sudo part.

You can use sudo with a -u switch.

Example:

sudo -u tomcat whoami