I have an Execute Shell Script action that sets a local variable. If the commands in the script return nothing (an empty string), then the action errors out. For example: this works (the 'ps' command returns text that contains the string "root"):
ps -cA -o user,pid,command | grep "root"
but this version causes an error ("garbage" is not found in the 'ps' result):
ps -cA -o user,pid,command | grep "garbage"
An empty (null) string should be as valid as any other string. If I add an 'echo x' before the 'ps', the action still errors out. Why does a null string result cause an error?