Error occurs when you insert a number in 'n' options.

./main.py -n 408

The process name is not vaild.
Traceback (most recent call last):
File "./main.py", line 35, in
main()
File "./main.py", line 25, in main
p = Psman(pinfo)
File "/home/wf/hub/psman/psman.py", line 19, in init
self.stat_file_field = self.get_process_info()
File "/home/wf/hub/psman/psman.py", line 33, in get_process_info
with open('/proc/%s/stat' % self.pid, 'rb') as f:
IOError: [Errno 2] No such file or directory: '/proc/-1/stat'