On Mon, Apr 13, 2009 at 04:49, Michael Alipio <[email protected]> wrote:
snip
> my $pid = fork ();
You must check to see if $pid is defined. If it isn't
then fork failed. The parentheses are oddly placed and
unnecessary.
> if ($pid == 0){
> exec ("top");
Again with the odd parentheses placement. Function
calls should look like this
func($blah, $blah);
Control structures should look like this
while (1) {
if ($it_is_true) {
That space is one of the ways humans use to tell
function calls and control structures apart.
> }else{
There is no need to make this an else statement, exec
replaces the current process, so the child can never
reach the rest of the code
> my $time = 0
You are missing a semi-colon at the end of this statement.
> while (<1>){
You are trying to read from a non-existent filehandle
named 1, I assume you meant to say
while (1) {
to get an infinite loop. This is also why your script
will never end: this while loop has no exit condition
and no calls to last in its body.
> sleep 1;
> $time++;
> if ($time == 10){
Why all of this mess instead of a simple sleep 10?
> kill 9, $pid;
SIGKILL is the kill of last resort, try SIGTERM instead.
It is also a good idea to reap the child with waitpid at
this point. Right after this statement is where a call
to last should go.
> }
> }
> }
It might be a good idea to run "stty sane" to fix the
terminal (top leaves it in a bad state if killed).
#!/usr/bin/perl
use strict;
use warnings;
die "could not fork" unless defined(my $pid = fork);
if ($pid == 0) {
exec "top";
die "could not exec top";
}
sleep 3;
kill 15, $pid;
waitpid $pid, 0;
#fix the terminal after killing top
system "stty", "sane";
--
Chas. Owens
wonkden.net
The most important skill a programmer can have is the ability to read.
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