Send output from a python server back to client

Question

Hello,

I now have a small java script server working correctly, called by:

<?php
  $handle = fsockopen("udp://78.129.148.16",12345);
  fwrite($handle,"vzctlrestart110");
  fclose($handle);
?>

On a remote server the following python server is running and executing the comand's

#!/usr/bin/python
import os
import socket
print "  Loading Bindings..."
settings = {}
line = 0
for each in open('/root/actions.txt', 'r'):
 line = line + 1
 each = each.rstrip()
 if each != "":
   if each[0] != '#':
     a = each.partition(':')
     if a[2]:
       settings[a[0]] = a[2]
     else:
       print "    Err @ line",line,":",each
print "  Starting Server...",
port = 12345
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.bind(("", port))
print "OK."
print "  Listening on port:", port
while True:
    datagram = s.recv(1024)
    if not datagram:
        break
    print "Rx Cmd:", datagram
    if settings.has_key(datagram):
      print "Launch:", settings[datagram]
      os.system(settings[datagram]+" &")
s.close()

Is it possible to easily send the output of the command back, when the server is started and is running a command the output is shown in the ssh window, however I want this output to be sent back to the browser of the original client, maybe setting the browser to wait for 15 seconds and then check for any data received via the socket.

I know I am asking quite a lot, however I am creating a PHP script which I have a large knowledge about, however my python knowledge lacks greatly.

Thanks, Ashley

Answer 1

Yes, you can read the output of the command. For this I would recommend the Python subprocess module. Then you can just s.write() it back.

Naturally this has some implications, you would probably have to let your PHP script run for a while longer since the process may be running slow.

# The pipe behaves like a file object in Python.
process = Popen(cmd, shell=True, stdout=PIPE)
process_output = ""
while process.poll():
     process_output += process.stdout.read(256)
s.write(process_output)

# Better yet.
process = Popen(cmd, shell=true, stdout=PIPE)
stdout, stderr = process.communicate() # will read and wait for process to end.
s.write(stdout)

Integrated into your code:

# ... snip ...
import subprocess
con, addr = s.accept()
while True:
    datagram = con.recv(1024)
    if not datagram:
        break
    print "Rx Cmd:", datagram
    if settings.has_key(datagram):
        print "Launch:", settings[datagram]
        process = subprocess.Popen(settings[datagram]+" &", shell=True, stdout=subprocess.PIPE)
        stdout, stderr = process.communicate()
        con.send(stdout)
    con.close()
s.close()

Answer 2

Here's an example of how to get the output of a command:

>>> import commands
>>> s =  commands.getoutput("ls *")
>>> s
'client.py'