utils_sys.py: Add function for finding process PIDS

Added small utility function get_pids_for(<list>). This
function reads the output of 'ps aux' and gets the pids
for any process in <list>.

Signed-off-by: Slancaster1 <[email protected]>

virttest/utils_sys.py

@@ -72,3 +72,30 @@ def get_host_bridge_id(session=None):
 
     host_bridges = re.findall(hostbridge_regex, output)
     return host_bridges if host_bridges else []
+
+
+def get_pids_for(process_names, session=None):
+    """
+    Given a list of names, retrieve the
+    PIDs for matching processes
+    Sort of equivalent to: 'ps aux | grep name'
+    :param process_names: List of process names to look for
+    """
+
+    status, ps_cmd = cmd_status_output("ps aux", shell=True, session=session)
+    if status != 0 or not ps_cmd:
+        return []
+
+    ps_output = ps_cmd.split("\n")
+    relevant_procs = [
+        proc
+        for proc in ps_output
+        for wanted_name in process_names
+        if wanted_name in proc
+    ]
+
+    relevant_procs = [line.split() for line in relevant_procs]
+    relevant_pids = [int(proc[1]) for proc in relevant_procs]
+    relevant_pids.sort()
+
+    return relevant_pids