Pass python script output to another programs stdin

I have an application that takes input, either from the terminal directly or I can use a pipe to pass the output of another program into the stdin of this one. What I am trying to do is use python to generate the output so it's formatted correctly and pass that to the stdin of this开发者_运维知识库 program all from the same script. Here is the code:

#!/usr/bin/python
import os 
import subprocess
import plistlib
import sys

def appScan():
    os.system("system_profiler -xml SPApplicationsDataType > apps.xml")
    appList = plistlib.readPlist("apps.xml")
    sys.stdout.write( "Mac_App_List\n"
    "Delimiters=\"^\"\n"
    "string50 string50\n"
    "Name^Version\n")
    appDict = appList[0]['_items']
    for x in appDict:
        if 'version' in x:
           print x['_name'] + "^" + x['version'] + "^"
        else:
           print x['_name'] + "^" + "no version found" + "^"
proc = subprocess.Popen(["/opt/altiris/notification/inventory/lib/helpers/aex-     sendcustominv","-t","-"], shell=False, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
proc.communicate(input=appScan())

For some reason this subprocess I am calling doesn't like what is coming into stdin. However if I remove the subprocess items and just have the script print to stdout and then call the script from the terminal (python appScan.py | aex-sendcustominv), aex-sendcustominv is able to accept the input just fine. Is there any way to take a functions output in python and send it to the stdin of an subprocess?

The problem is that appScan() only prints to stdout; appScan() returns None, so proc.communicate(input=appScan()) is equivalent to proc.communicate(input=None). You need appScan to return a string.

Try this (not tested):

def appScan():
    os.system("system_profiler -xml SPApplicationsDataType > apps.xml")
    appList = plistlib.readPlist("apps.xml")
    output_str = 'Delimiters="^"\nstring50 string50\nName^Version\n'
    appDict = appList[0]['_items']
    for x in appDict:
        if 'version' in x:
           output_str = output_str + x['_name'] + "^" + x['version'] + "^"
        else:
           output_str = output_str + x['_name'] + "^" + "no version found" + "^"
    return output_str

proc = subprocess.Popen(["/opt/altiris/notification/inventory/lib/helpers/aex-     sendcustominv","-t","-"], shell=False, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
proc.communicate(input=appScan())