signals

I have a script running on the background of my linux server and I would like to catch signals like reboot or anything that would kill this script and instead save any importante information before actually exiting. I think most of what I need to catch is, SIGINT, SIGTERM, SIGHUP, SIGKILL. How do catch any of these signals and have it execute an exit function otherwise keep executing whatever it was doing ? pseudo perl code: #!/usr/bin/perl use stricts; use warnings; while (true) { #my happy code is running #my happy code will sleep for a few until its breath is back to keep running. } #ops I

Back in the day when I was young and Unix was the new thing, creating a process that did not get killed when you logged out was a challenge. We used the nohup command to protect our persistent processes from the HUP signal. If we weren't careful, our processes would get killed when we logged off, or even closed the shell we started them from. Fast forward to today and I find I am surprised that the default appears to be exactly the opposite. On both Ubuntu and Red Hat systems I find that I can put nearly any process in the background, kill the parent shell, log off, anything and it just keeps

I am using SDL for an OpenGL application, running on Linux. My problem is that SDL is catching SIGINT and ignoring it. This is a pain because I am developing through a screen session, and I can't kill the running program with CTRL-C (the program the computer is running on is connected to a projector and has no input devices). Is there a flag or something I can pass to SDL so that it does not capture SIGINT? I really just want the program to stop when it receives the signal (ie when I press ctrl-c). Ctrl-C at the console generates an SDL_QUIT event. You can watch for this event using SDL

I have a Go program hosting a simple HTTP service on localhost:8080 so I can connect my public nginx host to it via the proxy_pass directive, as a reverse proxy to serve part of my site's requests. This is all working great, no problems there. I want to convert the Go program to host the HTTP service on a Unix domain socket instead of a local TCP socket for improved security and to reduce the unnecessary protocol overhead of TCP. PROBLEM : The problem is that Unix domain sockets cannot be reused once they are bind() to, even after program termination. The second time (and every time after) I

Setting the bash pipefail option (via set -o pipefail ) allows the script to fail if a non-zero error is caught where there is a non-zero error in any step of a pipe. However, we are running into SIGPIPE errors (error code 141), where data is written to a pipe that no longer exists. Is there a way to set bash to ignore SIGPIPE errors, or is there an approach to writing an error handler that will handle all error status codes but, say, 0 and 141? For instance, in Python, we can add: signal.signal(signal.SIGPIPE, signal.SIG_DFL) to apply the default behavior to SIGPIPE errors: ignoring them (cf.

I want ssh to forward the SIGTERM signal to the remote command. ssh root@localhost /root/print-signal.py Get PID of ssh: ps aux| grep print-signal Kill the matching ssh process: kill pid-of-ssh Unfortunately only the ssh process itself gets the signal, not the remote command ( print-signal.py ). The remote command does not terminate :-( How can I make ssh "forward" the SIGTERM signal to the remote command? I think you can do the following : ssh root@localhost /root/print-signal.py **Get PID of python file running ** ps aux| grep print-signal Kill the matching ssh process: ssh root@localhost

I am wrapping a fastcgi app in a bash script like this: #!/bin/bash # stuff ./fastcgi_bin # stuff As bash only executes traps for signals when the foreground script ends I can't just kill -TERM scriptpid because the fastcgi app will be kept alive. I've tried sending the binary to the background: #!/bin/bash # stuff ./fastcgi_bin & PID=$! trap "kill $PID" TERM # stuff But if I do it like this, apparently the stdin and stdout aren't properly redirected because it does not connect with lighttpds mod_fastgi, the foreground version does work. EDIT: I've been looking at the problem and this happens