Strange SIGINT propagation between Parent/Child sh scripts Post: 302359361

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Top Forums Shell Programming and Scripting Strange SIGINT propagation between Parent/Child sh scripts Post 302359361 by danie.ludick on Tuesday 6th of October 2009 10:56:08 AM

10-06-2009

Registered User

Strange SIGINT propagation between Parent/Child sh scripts

Good day,

I am trying to add signal handling capabilities to some of my scripts. Unfortunately, I am having some difficulty with the manner in which signals are propagated between parent/child processes. Consider the following example:

I have the following "parent" script:

Code:

#!/usr/bin/sh

child_id=0

SIGINT_handler()
{
     echo "SIGINT caught in Parent"
     if [  $child_id  -ne 0 ]
         then
            echo Parent sendingi: kill -n 2 $child_id
            kill -n 2 $child_id
     fi
}


echo parent running
trap 'echo parent exiting; exit' 0
trap 'SIGINT_handler' 2                            # Pass Signal 2 to child but don't die
./child &
child_id=$!
echo 'child_id = ' $child_id

# Wait until child-process exits
wait $child_id
WAIT_STATUS=$?
echo Wait Status recorded when parent continues: $WAIT_STATUS

echo Parent Still Running after the child exits!
sleep 1000

which calls the following "child" script (as a background process):

Code:

#!/usr/bin/sh

echo child started. pid is $$
#trap 'echo child exiting; exit 0' 0
trap 'echo child got signal 2; exit 0' 2
sleep 1000

When I execute the "parent" process with a ">./parent",
I observe that the expected behavior. I then send a
SIGINT to the "parent" via a ">kill -s SIGINT <ppid>" and
get the following screen output:

Quote:

SIGINT caught in Parent
Parent sending: kill -n 2 20944
Wait Status recorded when parent continues: 130
Parent Still Running after the child exits!

When I look at the processes that are still active, I see
that the child (and its sleep) has not been killed at all -
all that happened was that the sleep-process of the parent
was activated.

I would appreciate it if anybody has some idea what is happening
here.

danie.ludick

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LEARN ABOUT HPUX

create_child

create child(1m)														  create child(1m)

NAME

       create child - Creates a child pointer at the master replica of the parent directory

SYNOPSIS

       cdscp create child child-name clearinghouse clearinghouse-name

ARGUMENTS

       The full name of the child pointer.  The full name of a clearinghouse that contains a replica of the child directory.

DESCRIPTION

       The create child command creates a child pointer at the master replica of the parent directory.	When CDS looks up a name in the namespace,
       it uses child pointers to locate directory replicas.  Use the set cdscp preferred clearinghouse command	before	issuing  this  command	to
       ensure that the request is directed to the master replica.

   Privilege Required
       You must have insert permission to the parent directory.

NOTES

       Use  the  create  child	command  only  to  re-create a child pointer that is accidentally deleted. This command is designed only for trou-
       bleshooting.

       This command will fail if the associated directory does not exist.  If the associated directory exists, this command will  return  success-
       fully.

       This command is replaced at Revision 1.1 by the dcecp command and may not be provided in future releases of DCE.

EXAMPLE

       The  following  command	creates the child pointer in the parent directory /.:/subsys.  It uses the replica located at the /.:/subsys/NY_CH
       clearinghouse to fill in its replica set.

       cdscp> create child /.:/subsys clearinghouse /.:/subsys/NY_CH

RELATED INFORMATION

       Commands: delete child(1m), list child(1m), show child(1m)

																  create child(1m)

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