pipe and fork - communicating with your children
this example from a Well House Consultants training course
Source code: t3 Module: Y303
# A demonstration of how a process can be forked and
# the parent and child can later communicate via a
# pipe set up prior to forking. Signals and / or
# buffer tests on the file handle (not shown in this
# example) can be used to check whether or not parent
# and child have data to exchange without one of them
# blocking on a read
from os import *
status = -1
pingaling = popen("ping -q -c2 "+ip,"r")
line = pingaling.readline()
if not line: break
igot = re.findall(lifeline,line)
status = int(igot)
lifeline = re.compile(r"(\d) packets received")
# Single process ...
print "hello - multipinger"
# becomes two processes!
iptest = raw_input("What IP to test ")
if iptest == "": break
rend, wend = pipe()
gerald = fork()
if not gerald:
print "testing ",iptest
about = lifetest(iptest)
print "tested ",iptest
rz = "Result %s %d\n" % (iptest,about)
# convert file descriptor to file handle
whand = fdopen(wend,'w',0)
print "Off for a nice hot curry"
rhand = fdopen(rend,'r',0)
report = rhand.readline()
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