Most are probably familiar with the command diag sys top, to find processes that consume too high CPU/memory.

To find a specific PID of a processes, a command was introduced in v6 (I think), that allows you to search for PIDs for a given process.
Under follows an example of finding the PIDs for httpsd and subsequently killing them.

FortiGate60E # diag sys process pidof httpsd
24631
24638
24639

FortiGate60E # diag sys kill 9 24631
FortiGate60E # diag sys kill 9 24638
FortiGate60E # diag sys kill 9 24639
FortiGate60E #
FortiGate60E # diag sys process pidof httpsd
24644

FortiGate60E #