Experimental python script to kill processes on unix-like systems.

freeport.py

#!/usr/bin/python -W ignore::DeprecationWarning
import sys
import os

"""
Experimental python script to kill processes on unix-like systems.

https://gist.github.com/2726360

Looks for all established connections on a given port and kills their processes.
First command line argument must be the portnumber.
"""

SIMULATION=False
DEBUG=False

#SIMULATION=True
#DEBUG=True

CR="\r"
LF="\n"

def freeport(port):


  if DEBUG:
    print "Freeing port %s ..." % port

  # get process numbers of processes with established connections on this port:
  processlist = established_by_port(port)
  if DEBUG:
    print processlist

  # cut out the process numbers:
  processnumbers = cut_bytes(processlist,9,14)

  if (len(processnumbers) == 0):
    if DEBUG:
      print "... no processes found. OK."
    sys.exit()

  # kill all these processes:
  if DEBUG:
    print "killing: %s ..." % processnumbers
  if not SIMULATION:
    processes_left=kill(processnumbers)

  # some hung processes would need -9 and/or sudo: 

  # get process numbers of processes STILL ALIVE with established connections on this port:
  processlist = established_by_port(sys.argv[1])
  if DEBUG:
    print processlist

  # cut out the process numbers:
  processnumbers = cut_bytes(processlist,9,13)

  if (len(processnumbers) == 0):
    if DEBUG:
      print "... all processess killed. OK."
    sys.exit()

  # kill all these processes:
  if DEBUG:
    print "sudo killing -9: %s ..." % processnumbers
  if not SIMULATION:
    processes_left=kill(processnumbers,force=1)

  if DEBUG:
    print "Done. %s processes could not be killed." % len(processs_left)


def rtrim_crlf(s):
  """ remove any cr or lf character from the end of s."""
  if s == None:
    return s
  while 1:
    if len(s) == 0:
      return s
    if s[-1:] in [CR,LF]:
      s = s[:-1]
    else:
      return s

def create_cut_list(nfrom,nto):
  if (nfrom is None) and (nto is None):
    raise("nfrom and nto cannot both be None")
  if nfrom == nto:
    list = "%s" % nfrom
  elif nfrom is None:
     list="-%s" % nto
  elif nto is None:
     list="%s-" % nfrom
  else:
     list="%s-%s" % (nfrom,nto)
  return list
  
def cut(lines=[],params=""):
  """call the cut command on unix-like systems"""
  cmd = "cut"
  if params != "":
    cmd = cmd + " " + params
  res = call(cmd,lines)
  return res
 
def cut_by(code,lines=[],nfrom=None,nto=None,complement=0):
  list = create_cut_list(nfrom,nto)
  params = "%s %s" % (code,list)
  if complement:
    params = params + " --complement"
  res = cut(lines,params)
  return res

def cut_bytes(lines=[],nfrom=None,nto=None,complement=0):
  """the bytes version of the cut command"""
  return cut_by("-b",lines,nfrom,nto,complement) 

def cut_byte(lines,n,complement=0):
  """only 1 byte"""
  return cut_bytes(lines,n,n,complement) 

def cut_fields(lines=[],nfrom=None,nto=None,complement=0):
  """the fields version of the cut command"""
  return cut_by("-f",lines,nfrom,nto,complement) 

def cut_field(lines,n,complement=0):
  """only 1 field"""
  return cut_fields(lines,n,n,complement) 

def cut_characters(lines=[],nfrom=None,nto=None,complement=0):
  """the chars version of the cut command"""
  return cut_by("-c",lines,nfrom,nto,complement) 

def call(cmd,more_lines=[]):
  """
  executes the commandline cmd as a new process p and passes more_lines (which must be a list of lines)
  as input to p. returns p's output as a list of lines.
  """

  fi,fo = os.popen2(cmd,'t')
  for l in  more_lines:
    fi.write(l+"\n")
  fi.close()
  rescr = fo.readlines()
  # remove the trailing newline chracters from the resulting lines:
  res = []
  for l in rescr:
    res.append(rtrim_crlf(l))
  fo.close()
  return res

def established_by_port(port):
  # returns a list of processes with established connections on the port
  cmd = "lsof -i :%s|grep ESTABLISHED" % port
  res = call(cmd)
  return res

def kill(process_list=[],force=0):
  # kill all processes by pids in the list
  for p in process_list:
    if force:
      call("sudo kill -9 %s" % p)
    else:
      call("kill -9 %s" % p)


if __name__ == '__main__':
  freeport (sys.argv[1])