The following compilable C++ program catches signals as expected if it runs directly from shell /tmp/a.out.
However, this program fails to catch any signal and silently terminates if it is fired by Debian's start-stop-daemon. (My real life multiple threaded program does not silently terminates. Instead, segmentation fault occurs from pthread libray.) --------------- ( Better code formatted message can be found here: http://stackoverflow.com/questions/37076470/c-program-launched-by-start-stop-daemon-fails-to-catch-signals ) File "/tmp/t.cpp": #include <iostream> #include <signal.h> //sigaction, signal() #include <unistd.h> //sleep() #include <cstring> //memset() #include <cstdlib> //exit() static int caught_signal=-1; void signal_handler(int signal_number) { std::cerr << "Caught signal# " << signal_number << std::endl; caught_signal=signal_number; } void accept_signals() { struct sigaction actions; memset(&actions,0,sizeof(actions)); actions.sa_handler=signal_handler; int result; if( (result=sigaction(SIGTERM,&actions,NULL)) != 0 || (result=sigaction(SIGHUP,&actions,NULL)) != 0 ){ std::cerr << "sigaction() failed: " << result << std::endl; exit(EXIT_FAILURE); } } int main(int argc,char ** argv) { accept_signals(); while(true){ if(caught_signal >= 0){ switch(caught_signal){ case SIGHUP:{ std::cerr << "Reload" << std::endl; break; } default:{ //SIGTERM std::cerr << "Terminate" << std::endl; return 0; } } } sleep(1); } return 0; } --------------- File "/tmp/t.sh": #!/bin/sh ### BEGIN INIT INFO # Provides: progam # Default-Start: 2 3 4 5 # Default-Stop: 0 1 6 # Short-Description: My Program # Description: Test signals. ### END INIT INFO PATH=/sbin:/bin:/usr/sbin:/usr/bin DAEMON=/tmp/a.out NAME=progam DESC="My Program" SCRIPTNAME=/etc/init.d/$NAME PIDFILE=/tmp/progam.pid test -x $DAEMON || exit 0 #set -x . /lib/lsb/init-functions case "$1" in start) log_daemon_msg "Starting $DESC" $NAME start-stop-daemon --start --oknodo --quiet --pidfile $PIDFILE --exec $DAEMON -b -m -- log_end_msg $? ;; stop) log_daemon_msg "Stopping $DESC" $NAME start-stop-daemon --stop --retry TERM/10 --quiet --pidfile $PIDFILE --exec $DAEMON --remove-pidfile log_end_msg $? ;; reload|force-reload) log_daemon_msg "Reloading $DESC" $NAME start-stop-daemon --stop --signal HUP --retry 10 --quiet --pidfile $PIDFILE --exec $DAEMON log_end_msg $? ;; restart) log_daemon_msg "Restarting $DESC" $NAME $0 stop $0 start ;; status) status_of_proc -p "$PIDFILE" "$DAEMON" "$NAME" && exit 0 || exit $? ;; *) echo "Usage: $SCRIPTNAME {start|stop|restart|reload|force-reload|status}" >&2 exit 1 ;; esac exit 0 --------------- Running results: john@host:/tmp$ ./t.sh start [ ok ] Starting My Program: progam john@host:/tmp$ ps ax|grep a.out 8911 ? S 0:00 /tmp/a.out 8931 pts/4 S+ 0:00 grep a.out john@host:/tmp$ ./t.sh stop [ ok ] Stopping My Program: progam john@host:/tmp$ ps ax|grep a.out 8961 pts/4 S+ 0:00 grep a.out john@host:/tmp$ ./a.out& [1] 8963 john@host:/tmp$ ps ax|grep a.out 8963 pts/4 S 0:00 ./a.out 8967 pts/4 S+ 0:00 grep a.out john@host:/tmp$ kill -TERM 8963 john@host:/tmp$ Caught signal# 15 Terminate ps ax|grep a.out 8973 pts/4 S+ 0:00 grep a.out [1]+ Done ./a.out john@host:/tmp$ exit --------------- Why the program terminates, which I believe crashes, when signals arrive if it is launched by the aforementioned shell script? -- http://www.fastmail.com - Email service worth paying for. Try it for free
