Hi
Johan Geldenhuys wrote:
> Hugo,
>
> I see that 'os.execcvp()' doesn't actually make two seperate processes.
> This is what I have working now:
> """
>
> import os, signal, time
> pid = os.fork()
> print 'pid; ',pid
> if pid == 0: #child process
> #os.execvp('tcpdump', ['tcpdump', '-i modem0 > cap1.txt'])
> os.execvp('ping', ['ping', '127.0.0.1 -c 30 > cap.txt'])
The following line (sleep)is superluous, as it is no longer your python
script after calling exec()
Your process (in this case the child process)is replaced with a copy of
ping in memory.
> time.sleep(5)
> kill(pid)
>
> def kill(pid, signal=signal.SIGTERM):
> print "trying to kill pid...", pid
> os.kill(pid, signal)
> os.waitpid(pid, 0)
> print "Killed %d"%pid
> """
>
> The ping command is executed but the part where it must put the replies
> in the file is not recognized. How do I use the addisional arguments to
> be seen?
>
Mmm no, this line:
> os.execvp('ping', ['ping', '127.0.0.1 -c 30 > cap.txt'])
uses *shell redirection*.. guess who has to interpret the whole > thing..
As you are using no shell, the '>' argument is passed to the ping
program, which knows nothing of handling it the way you expect it.
What you're doing is equivalent to (in my workstation)
[EMAIL PROTECTED]:~# ping 192.168.0.8 ">" cap.txt
ping: unknown host >
You have to call a shell if you want to use redirection, otherwise you
will have to use python to send all of ping's output to a file (which
would be a nice exercise, IMHO ;) )
Hugo
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