Hi,
I have this code:
die "Could not fork command1!" unless defined (my $command1_pid = fork);
if ($command1_pid == 0){
open EXTERNAL_PROG1, "external_prog1 |" or die "Can't run external_prog1";
while (<EXTERNAL_PROG1>){
if (/pattern/){
die "Could not fork command2" unless defined (my $command2_pid = fork);
die "Could not fork command3" unless defined (my $command3_pid = fork);
if ($command2_pid == 0){
`external_prog2`
}
}
waitpid($command2_pid,0);
if ($command3_pid == 0){
`external_prog3`;
}
waitpid($command3_pid, 0);
}
}
That is, run external_prog1 and watch the output.. as soon as it sees a
particular pattern, run two other external commands at the same time. However,
with the above code, I keep getting duplicated external_prog2 process everytime
i run the script. I need to track both PIDs of external_prog2 and 3 as I need
to kill them later in the code. However, i'm having trouble running them at the
same time.
if I will put a "kill 15, $command3_pid" right after the first waitpid, i will
surely kill one of those two command 2 process. I tried several places to put
"die" lines and "waitpids" but I couldn't get it right. It's either they don't
run at the same time or they will run but command 2 has a twin brother.
Any idea how to solve this chicken and egg problem?
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