Python Library for Linux Process Management

Python library for Linux process management

To start/stop python sub processes you can use the subprocess module.
To check whether they are running you might use psutil:

>>> import psutil
>>> pid = 1034  # some pid
>>> psutil.pid_exists(pid)
True
>>>

...or this (it will also check if the PID has been reused):

>>> p = psutil.Process(pid)
>>> p.is_running()
True
>>>

is there a way to start/stop linux processes with python?

Have a look at the subprocess module.
You can also use low-level primitives like fork() via the os module.

process management with python: execute service or systemd or init.d script

I found a way using systemd dbus interface. Here is the code:

import dbus
import subprocess
import os
import sys
import time

SYSTEMD_BUSNAME = 'org.freedesktop.systemd1'
SYSTEMD_PATH = '/org/freedesktop/systemd1'
SYSTEMD_MANAGER_INTERFACE = 'org.freedesktop.systemd1.Manager'
SYSTEMD_UNIT_INTERFACE = 'org.freedesktop.systemd1.Unit'

bus = dbus.SystemBus()

proxy = bus.get_object('org.freedesktop.PolicyKit1', '/org/freedesktop/PolicyKit1/Authority')
authority = dbus.Interface(proxy, dbus_interface='org.freedesktop.PolicyKit1.Authority')
system_bus_name = bus.get_unique_name()

subject = ('system-bus-name', {'name' : system_bus_name})
action_id = 'org.freedesktop.systemd1.manage-units'
details = {}
flags = 1            # AllowUserInteraction flag
cancellation_id = '' # No cancellation id

result = authority.CheckAuthorization(subject, action_id, details, flags, cancellation_id)

if result[1] != 0:
    sys.exit("Need administrative privilege")

systemd_object = bus.get_object(SYSTEMD_BUSNAME, SYSTEMD_PATH)
systemd_manager = dbus.Interface(systemd_object, SYSTEMD_MANAGER_INTERFACE)

unit = systemd_manager.GetUnit('cups.service')
unit_object = bus.get_object(SYSTEMD_BUSNAME, unit)
#unit_interface = dbus.Interface(unit_object, SYSTEMD_UNIT_INTERFACE)

#unit_interface.Stop('replace')
systemd_manager.StartUnit('cups.service', 'replace')

while list(systemd_manager.ListJobs()):
    time.sleep(2)
    print 'there are pending jobs, lets wait for them to finish.'

prop_unit = dbus.Interface(unit_object, 'org.freedesktop.DBus.Properties')

active_state = prop_unit.Get('org.freedesktop.systemd1.Unit', 'ActiveState')

sub_state = prop_unit.Get('org.freedesktop.systemd1.Unit', 'SubState')

print active_state, sub_state

Which is the best way to get a list of running processes in unix with python?

This works on Mac OS X 10.5.5. Note the capital -U option. Perhaps that's been your problem.

import subprocess
ps = subprocess.Popen("ps -U 0", shell=True, stdout=subprocess.PIPE)
print ps.stdout.read()
ps.stdout.close()
ps.wait()

Here's the Python version

Python 2.5.2 (r252:60911, Feb 22 2008, 07:57:53) 
[GCC 4.0.1 (Apple Computer, Inc. build 5363)] on darwin

Simple remote process monitoring with Python

The Fabric library may be of interest to you.

Windows process management using Python

On Windows, you can use WMI:

import win32com.client

def find_process(name):
    objWMIService = win32com.client.Dispatch("WbemScripting.SWbemLocator")
    objSWbemServices = objWMIService.ConnectServer(".", "root\cimv2")
    colItems = objSWbemServices.ExecQuery(
         "Select * from Win32_Process where Caption = '{0}'".format(name))
    return len(colItems)

print find_process("SciTE.exe")

Monitor Process in Python?

There are a couple of options,

1: the more crude but obvious would be to do some text processing against:

os.popen('tasklist').read()

2: A more involved option would be to use pywin32 and research the win32 APIs to figure out what processes are running.

3: WMI (I found this just now), and here is a vbscript example of how to query the machine for processes through WMI.

Is there a way to change effective process name in Python?

Simply put, there's no portable way. You'll have to test for the system and use the preferred method for that system.

Further, I'm confused about what you mean by process names on Windows.

Do you mean a service name? I presume so, because nothing else really makes any sense (at least to my non-Windows using brain).

If so, you need to use Tim Golden's WMI interface and call the .Change method on the service... at least according to his tutorial.

For Linux none of the methods I found worked except for this poorly packaged module that sets argv[0] for you.

I don't even know if this will work on BSD variants (which does have a setproctitle system call). I'm pretty sure argv[0] won't work on Solaris.

Total memory used by Python process?

Here is a useful solution that works for various operating systems, including Linux, Windows, etc.:

import os, psutil
process = psutil.Process(os.getpid())
print(process.memory_info().rss)  # in bytes 

Notes:

• do pip install psutil if it is not installed yet

• handy one-liner if you quickly want to know how many MB your process takes:

  import os, psutil; print(psutil.Process(os.getpid()).memory_info().rss / 1024 ** 2)
  

• with Python 2.7 and psutil 5.6.3, it was process.memory_info()[0] instead (there was a change in the API later).

---

Related Topics