`fid-kill` doesn't send a kernel signal to the process but since _murex_ is
a multi-threaded shell with a single signal, `fid-kill` will send a
cancellation context to any builtins executing (which covers builtins,
aliases, public and private functions and any external executables running
which were launched within the current _murex_ shell).

The FID (function ID) sent is not the same as a POSIX (eg Linux, macOS, BSD)
PID (process ID). You can obtain a FID from `fid-list`.