How to print the top 10 users by the number of processes?

How could I print the to开发者_运维知识库p 10 users on a linux distribution by the number of processes they have running? I have managed to do this using a shell script, but now I'm interested at how I can do this using Python.

Parsing the output of ps aux is not very pleasant, and can be tricky because the format is not guaranteed to be the same on all Linux systems.

Installing a third-party tool like psutil or PSI should make things easy and portable.

If you are looking for a Linux-only solution without installing a third-party module, then the following might help:

On modern Linux systems, all processes are listed in the /procs directory by their pid. The owner of the directory is the owner of the process.

import os
import stat
import pwd
import collections
import operator

os.chdir('/proc')
dirnames=(dirname for dirname in os.listdir('.') if dirname.isdigit())
statinfos=(os.stat(dirname) for dirname in dirnames)
uids=(statinfo[stat.ST_UID] for statinfo in statinfos)
names=(pwd.getpwuid(uid).pw_name for uid in uids)
counter=collections.defaultdict(int)
for name in names:
    counter[name]+=1
count=counter.items()
count.sort(key=operator.itemgetter(1),reverse=True)
print('\n'.join(map(str,count[:10])))

yields

('root', 130)
('unutbu', 55)
('www-data', 7)
('avahi', 2)
('haldaemon', 2)
('daemon', 1)
('messagebus', 1)
('syslog', 1)
('Debian-exim', 1)
('mysql', 1)