There are two possible error scenarios for CallPgrep.  One indicates a broken system (no pgrep command) and one is a normal error state of pgrep meaning no processes found for the criteria given (in this case the parent pid does not exist or the process simply has no children).  The later case is quite usefull to know about so I added a static error for this case.
There are two possible error scenarios for CallPgrep.  One indicates a broken
system (no pgrep command) and one is a normal error state of pgrep
meaning no processes found for the criteria given (in this case the parent
pid does not exist or the process simply has no children).  The later case
is quite usefull to know about so I added a static error for this case.

influxdb/gopsutil,influxdb/gopsutil