Some of the jobs I submit to the grid take a long time (say, 30-60 minutes) and I would like to check on their status without having to log back into the labs.

I was hoping I could run shell_exec('qstat') in PHP and display its output on a web page. While shell_exec() works with other commands—e.g. echo shell_exec('whoami') correctly displays my tool's username on the webpage—for reasons I cannot explain, the output of shell_exec('qstat') is always blank. When I run qstat on the CLI at that same time, it does show me the familiar table output of ongoing jobs.

Any idea why that is the case? Has anyone already created a solution for fetching a list of active jobs from the grid and displaying it on a web-based status page for your tool?