SIG management in PERL

[Enrico Venturi]

Hello colleagues,
my 1st PERL program is almost completed ;-)

I'd like to set up a signal handler for SIGCHLD exception;
I knew that the hash SIG array should be initialized in such a way:
$SIG(CHLD) = \& my_handler;

The question is:
what have I to do / declare / include to let my program know the SIG hash?? (It's a global hash variable)

thanks
enrico

[H.Merijn Brand (procura · Accepted solution]

Simple answer: nothing. It's an internal global (magic) hash :)

$SIG{CHLD} = sub { print STDERR "Got sig CHLD\n" };

note that you used the wrong parens. %SIG is a hash, so you will have to use braces.

Enjoy, Have FUN! H.Merijn

[A. Clay Stephenson]

All you have to do is treat it as a hash.

$SIG{CHLD} = \&my_handler;

another example to ignore hangup's:
$SIG{HUP} = 'IGNORE';

[Enrico Venturi]

Ok, thanks a lot!
Now I'm receiving continuously signals about children unknown who die .....
Why????? ;-)

[A. Clay Stephenson]

I'm going to go way out on a limb here and tell you "because you have child processes that dying". For example, if you spawn an external command a SIGCHLD is sent when it terminates. Bear in mind, the default behavior for SIGCHLD is to ignore it. It's more typical to choose another signal with which to communicate with a parent process.

[H.Merijn Brand (procura]

Are you using system (), qx//, open "|-", or open "-|" ?

All these cause child processes to be started

# man perlipc

Enjoy, Have FUN! H.Merijn