kill-trap

basak · 08-21-2006, 03:02 PM

hi

In the "traptest" script below I want the script say "bye" and exit if it gets a SIGHUP signal.
In the "mycommand" script which is called from "traptest" I send the SIGHUP signal.

#!/bin/bash
#mycommand

calledprg=
while [ "$1" != "" ]; do
case $1 in
-s ) shift
calledprg=$1
;;
* ) exit 1

esac
shift
done

if [ "$calledprg" != "" ];then
pkill -s 1 $calledprg
fi
exit

#!/bin/bash
#traptest

PROGNAME=$(basename $0)
echo "$PROGNAME"
trap " echo "byeeeeeeeeeee" ; exit " SIGHUP

mycommand -s $PROGNAME
while :
do
echo "sleeeeppppp"
sleep 60
done

but I get

line 5: trap: have: invalid signal specification
line 5: trap: finished ; exit : invalid signal specification

what is wrong with these 2 scripts?

Also in some tutorials
they say SIGKILL should not be used if not urgent.Why?Instead of SIGKILL what would be used that makes sure that the program will be killed in any case?(in another script I used pkill -s 9 but I am not confident because of these comments

)

Thank u for reading all these

and thank u much more if u have any idea

jailbait · 08-21-2006, 03:56 PM

Change the line:

trap " echo "byeeeeeeeeeee" ; exit " SIGHUP

to:

trap ' echo "byeeeeeeeeeee" ; exit ' SIGHUP

--------------------
Steve Stites

basak · 08-21-2006, 04:46 PM

Thanks ,but there is still the problem that "mycommand" does not make "traptest" exit

basak · 08-21-2006, 06:48 PM

Code:

#!/bin/bash
#traptest

PROGNAME=$(basename $0)
echo "$PROGNAME"
trap ' echo "byeeeeeeeeeee" ; exit ' SIGHUP


mycommand -s $PROGNAME
while :
do
echo "sleeeeppppp"
sleep 60
done

Code:

#!/bin/bash
#mycommand

calledprg=
while [ "$1" != "" ]; do
case $1 in
-s ) shift
calledprg=$1
;;
* ) exit 1

esac
shift
done

#--------------------------
# some other work done here
# 
#--------------------------
if [ "$calledprg" != "" ];then
pkill -s 1 $calledprg   ##sends the SIGHUP signal to traptest
fi
exit

that looked better I guess

Traptest never gets out of the while loop even though it should exit when "mycommand" sends it the SIGHUP signal..

jailbait · 08-21-2006, 08:05 PM

I followed your logic through to this line:

pkill -s 1 $calledprg ##sends the SIGHUP signal to traptest

In that line the value of $calledprg is "bash" so you are not trying to pkill traptest, you are trying to pkill bash. You are sending SIGHUP to bash and bash is ignoring you.

I suggest that you forget about basename and use pid. Have traptest send its pid to mycommand and have mycommand pkill the ppid.

-----------------------
Steve Stites

basak · 08-22-2006, 05:05 AM

I am sorry but passing the PID does not solve the problem..Can the problem be due to the fact that mycommand runs in a subshell when it is called ,and passing traptest's PID or name is useless because in the subshell shell in which mycommand runs there is no such running program to kill ...???????????

jailbait · 08-22-2006, 09:41 AM

"I am sorry but passing the PID does not solve the problem."

Could you post the code where you passed the pid and it didn't work?

-------------------
Steve Stites

basak · 08-23-2006, 10:10 AM

Code:

#!/bin/bash
#traptest

trap " echo "byeeeeeeeeeee" ; exit " SIGHUP

mypid=$(ps | grep traptest |awk '{print $1}')
mycommand -s $mypid
while :
do
echo "sleeeeppppp"
sleep 5
done

Code:

#!/bin/bash
#mycommand

calledprg=
while [ "$1" != "" ]; do
             case $1 in
             -s ) shift
                  calledprg=$1
                  ;;
              * ) exit 1

   esac
   shift
   done

if [ "$calledprg" != "" ];then
kill -SIGHUP $calledprg
fi
exit

thank u for your help jailbait

Also can the problem be that "mycommand" sends the signal to "traptest" when its in sleeping mode and its pid is not the same any more???(I could not figure out why this signal handling does not work

I have been trying everything during these last two days,but I have nothing in the end

((

basak · 08-23-2006, 10:12 AM

+
I could not use the "pidof" command due to system settings,it is not available to my bash shell..

basak · 08-23-2006, 03:02 PM

basak · 08-23-2006, 05:38 PM

can the problem be due to the fact that

Note that while a parent process gets the process ID of the child process, and can thus pass arguments to it, the reverse is not true. This can create problems that are subtle and hard to track down.

as written in

http://elibrary.fultus.com/technical.../internal.html

that "mycommand" is a child process and parent process "tarptest" can not pass its PID to a child process????????