Re: fork and exit needed?
On Tue, 28 Nov 2006 04:30:09 -0600, Nick Craig-Wood [EMAIL PROTECTED] wrote: I'm not sure how you do open stdout to /dev/null in python though! I suspect something like this... import posix posix.close(1) posix.open(/dev/null, posix.O_WRONLY) Thanks everyone, but no go :-/ Neither the above nor sys.stdout = open(os.devnull, 'w') trigger the application. This is a script that is launched by the Asterisk open-source PBX server when a call comes in. Its goal is to broadcast some messages to a Windows caller ID application that is installed on all client hosts so that they know who's calling. Before I go ask in an Asterisk forum, is there some Python-related issue that experienced Python developers can spot in this rewrite of a Perl script that works? Here's the original Perl script: http://www.voip-info.org/wiki/view/Asterisk+NetCID Here's my Python rewrite: http://codecomplete.free.fr/asterisk/python_cid.txt Yes, I changed the UDP port from 42685 to 42687 so that my development client host is the only one getting the broadcast :-) Thank you! -- http://mail.python.org/mailman/listinfo/python-list
Re: fork and exit needed?
On Thu, 30 Nov 2006 15:38:11 +0100, Vincent Delporte [EMAIL PROTECTED] wrote: Here's my Python rewrite: http://codecomplete.free.fr/asterisk/python_cid.txt More information. Here's what Asterisk says when I call in: *CLI -- Executing LookupCIDName(SIP/fxo-0844e458, ) in new stack -- Changed Caller*ID name to Work -- Executing AGI(SIP/fxo-0844e458, ncid.python.agi|087077|Bureau Freebox) in new stack -- Launched AGI Script /var/lib/asterisk/agi-bin/ncid.python.agi Failed to execute '/var/lib/asterisk/agi-bin/ncid.python.agi': Exec format error -- AGI Script ncid.python.agi completed, returning 0 FWIW, I wrote the original in a Windows text editor, and copy-pasted the script in Asterisk by sshing into the server. CRLF vs. CR issue? Something else? Thanks. -- http://mail.python.org/mailman/listinfo/python-list
Re: fork and exit needed?
On Thu, 30 Nov 2006 15:48:53 +0100, Vincent Delporte [EMAIL PROTECTED] wrote: -- Launched AGI Script /var/lib/asterisk/agi-bin/ncid.python.agi Failed to execute '/var/lib/asterisk/agi-bin/ncid.python.agi': Exec format error Stupid me :-/ Forgot the all-important #!/usr/bin/python Sorry for the disturbance.. -- http://mail.python.org/mailman/listinfo/python-list
Re: fork and exit needed?
Vincent Delporte wrote: On Thu, 30 Nov 2006 15:38:11 +0100, Vincent Delporte [EMAIL PROTECTED] wrote: Here's my Python rewrite: http://codecomplete.free.fr/asterisk/python_cid.txt First line of your script should be: #! /usr/bin/env python which is how Linux knows what interpreter to use for the script. HTH, Mike -- Mike C. Fletcher Designer, VR Plumber, Coder http://www.vrplumber.com http://blog.vrplumber.com -- http://mail.python.org/mailman/listinfo/python-list
Re: fork and exit needed?
On Thu, 30 Nov 2006 10:18:24 -0500, Mike C. Fletcher [EMAIL PROTECTED] wrote: which is how Linux knows what interpreter to use for the script. Thanks. That's what I found out after a bit more research. I didn't pay attention to this because it's not needed to run under Windows, and I was focusing on the fork() and stdout thing. -- http://mail.python.org/mailman/listinfo/python-list
Re: Really closing stdout (was: fork and exit needed?)
Mitja Trampus [EMAIL PROTECTED] wrote: Nick Craig-Wood wrote: I'm not sure how you do open stdout to /dev/null in python though! I suspect something like this... import posix posix.close(1) posix.open(/dev/null, posix.O_WRONLY) Yes, you're close enough... The explanations are here: http://www.google.com/search?q=python%20close%20stdout, I like this one in particular: http://www.python.org/infogami-faq/library/why-doesn-t-closing-sys-stdout-stdin-stderr-really-close-it/ If you explicitly want to leave file descriptors 0-2 present (Do you gain anything by not closing them? If you know, do tell...), It is traditional I think... From the unix FAQ, http://www.erlenstar.demon.co.uk/unix/faq.txt :- 6. `close()' fds 0, 1, and 2. This releases the standard in, out, and error we inherited from our parent process. We have no way of knowing where these fds might have been redirected to. Note that many daemons use `sysconf()' to determine the limit `_SC_OPEN_MAX'. `_SC_OPEN_MAX' tells you the maximun open files/process. Then in a loop, the daemon can close all possible file descriptors. You have to decide if you need to do this or not. If you think that there might be file-descriptors open you should close them, since there's a limit on number of concurrent file descriptors. 7. Establish new open descriptors for stdin, stdout and stderr. Even if you don't plan to use them, it is still a good idea to have them open. The precise handling of these is a matter of taste; if you have a logfile, for example, you might wish to open it as stdout or stderr, and open `/dev/null' as stdin; alternatively, you could open `/dev/console' as stderr and/or stdout, and `/dev/null' as stdin, or any other combination that makes sense for your particular daemon. but pointing do /dev/null, you could do: null = os.open(os.devnull,os.O_WRONLY) os.dup2(null,0) os.dup2(null,1) os.dup2(null,2) os.close(null) Untested. Ah, dup2() was on the tip of my mind's tongue ;-) You could write it like this, and then it even works on Windows! import os import sys import time print os.getpid() null = os.open(os.devnull,os.O_RDWR) os.dup2(null, sys.stdin.fileno()) os.dup2(null, sys.stdout.fileno()) os.dup2(null, sys.stderr.fileno()) os.close(null) print You won't see this print sys.stderr, Or this time.sleep(60) -- Nick Craig-Wood [EMAIL PROTECTED] -- http://www.craig-wood.com/nick -- http://mail.python.org/mailman/listinfo/python-list
Re: fork and exit needed?
In [EMAIL PROTECTED], Vincent Delporte wrote: Anyone knows if those lines are necessary, why, and what their alternative is in Python? --- open STDOUT, '/dev/null'; sys.stdout = open(os.devnull, 'w') Ciao, Marc 'BlackJack' Rintsch -- http://mail.python.org/mailman/listinfo/python-list
Re: fork and exit needed?
Marc 'BlackJack' Rintsch [EMAIL PROTECTED] wrote: In [EMAIL PROTECTED], Vincent Delporte wrote: Anyone knows if those lines are necessary, why, and what their alternative is in Python? open STDOUT, '/dev/null'; sys.stdout = open(os.devnull, 'w') This doesn't have the desired effect If you run this import os,sys,time print os.getpid() sys.stdout = open(os.devnull, 'w') time.sleep(60) It prints its pid. $ ls -l /proc/32004/fd total 4 lrwx-- 1 ncw ncw 64 Nov 28 09:55 0 - /dev/pts/17 lrwx-- 1 ncw ncw 64 Nov 28 09:55 1 - /dev/pts/17 lrwx-- 1 ncw ncw 64 Nov 28 09:55 2 - /dev/pts/17 l-wx-- 1 ncw ncw 64 Nov 28 09:55 3 - /dev/null That quite clearly shows that stdout isn't /dev/null which is required for proper deamonisation under unix. I'm not sure how you do open stdout to /dev/null in python though! I suspect something like this... import posix posix.close(1) posix.open(/dev/null, posix.O_WRONLY) -- Nick Craig-Wood [EMAIL PROTECTED] -- http://www.craig-wood.com/nick -- http://mail.python.org/mailman/listinfo/python-list
Re: fork and exit needed?
Nick Craig-Wood wrote: If you run this import os,sys,time print os.getpid() sys.stdout = open(os.devnull, 'w') time.sleep(60) It prints its pid. and not only that, if you run print world, print hello it prints hello world in the wrong order! /F -- http://mail.python.org/mailman/listinfo/python-list
Re: fork and exit needed?
Dennis Lee Bieber [EMAIL PROTECTED] wrote: On Tue, 28 Nov 2006 04:30:09 -0600, Nick Craig-Wood [EMAIL PROTECTED] declaimed the following in comp.lang.python: If you run this import os,sys,time print os.getpid() sys.stdout = open(os.devnull, 'w') time.sleep(60) It prints its pid. I would hope so, as you performed the print BEFORE reassigning stdout... That is what I intended. I wanted the pid to look in /proc/pid/fd to see what file descriptors were really open. import os,sys,time print pre:, os.getpid() sys.stdout = open(os.devnull, 'w') print post:, os.getpid() time.sleep(60) (Granted, I'm on WinXP; I also suspect the original stdout is still open in the background, maybe dualled with stderr?) Yes that is the point - the original stdout is still open. I don't think this discussion is relevant to windows though - windows has its own way of making daemons. -- Nick Craig-Wood [EMAIL PROTECTED] -- http://www.craig-wood.com/nick -- http://mail.python.org/mailman/listinfo/python-list
Re: Really closing stdout (was: fork and exit needed?)
Nick Craig-Wood wrote: open STDOUT, '/dev/null'; sys.stdout = open(os.devnull, 'w') $ ls -l /proc/32004/fd total 4 lrwx-- 1 ncw ncw 64 Nov 28 09:55 0 - /dev/pts/17 lrwx-- 1 ncw ncw 64 Nov 28 09:55 1 - /dev/pts/17 lrwx-- 1 ncw ncw 64 Nov 28 09:55 2 - /dev/pts/17 l-wx-- 1 ncw ncw 64 Nov 28 09:55 3 - /dev/null I'm not sure how you do open stdout to /dev/null in python though! I suspect something like this... import posix posix.close(1) posix.open(/dev/null, posix.O_WRONLY) Yes, you're close enough... The explanations are here: http://www.google.com/search?q=python%20close%20stdout, I like this one in particular: http://www.python.org/infogami-faq/library/why-doesn-t-closing-sys-stdout-stdin-stderr-really-close-it/ If you explicitly want to leave file descriptors 0-2 present (Do you gain anything by not closing them? If you know, do tell...), but pointing do /dev/null, you could do: null = os.open(os.devnull,os.O_WRONLY) os.dup2(null,0) os.dup2(null,1) os.dup2(null,2) os.close(null) Untested. More info on file descriptors and python here: http://docs.python.org/lib/os-fd-ops.html Mitja -- http://mail.python.org/mailman/listinfo/python-list
Re: fork and exit needed?
On Tue, 28 Nov 2006 08:30:03 -0600, Nick Craig-Wood [EMAIL PROTECTED] wrote: import os,sys,time print pre:, os.getpid() sys.stdout = open(os.devnull, 'w') print post:, os.getpid() time.sleep(60) (Granted, I'm on WinXP; I also suspect the original stdout is still open in the background, maybe dualled with stderr?) Yes that is the point - the original stdout is still open. I don't think this discussion is relevant to windows though - windows has its own way of making daemons. Thanks everyone. I'll see if the Python script runs OK in an Asterisk PBX on Linux. -- http://mail.python.org/mailman/listinfo/python-list
fork and exit needed?
Hi I'm a Python newbie, and would like to rewrite this Perl scrip to be run with the Asterisk PBX: http://www.voip-info.org/wiki/view/Asterisk+NetCID Anyone knows if those lines are necessary, why, and what their alternative is in Python? --- open STDOUT, '/dev/null'; fork and exit; --- Thank you. -- http://mail.python.org/mailman/listinfo/python-list
Re: fork and exit needed?
Vincent Delporte wrote: Hi I'm a Python newbie, and would like to rewrite this Perl scrip to be run with the Asterisk PBX: http://www.voip-info.org/wiki/view/Asterisk+NetCID Anyone knows if those lines are necessary, why, and what their alternative is in Python? open STDOUT, '/dev/null'; Either redefine stdout to an open file object for /dev/null or run the script as script.py /dev/null fork and exit; something like: if os.fork(): sys.exit(0) Tells the parent to exit after the fork while the child keeps running. These are both steps in becoming a daemon (the comp.unix.programmer FAQ, while skewed toward C, explains why some of these steps are needed). -- http://mail.python.org/mailman/listinfo/python-list
