I would like to run a shell script on the web server and use its output to fill the labels of a radio list. I'm thinking to use the beforeQuestionRender hook. Is there an example (php) for this? Thanks!

beforeQuestionRender can not be used with shell script : it happen each time a question is shown in HTML …

A shell script can update label in DB why not.

For "shell script" see www.limesurvey.org/manual/Plugin_events#CLI_Events

Thanks so much for your help. I am able to run shell scripts now, through
$output = shell_exec($shFile);

But getting the lines from $output to the options of a list question is still a challenge. I'm trying toolsDomDocument. If you have samples please give me some pointers.