Re: Killing processes

Hello deyaneria,

The logic of the do ... while loop is wrong. If the user answers “N”, the script still asks for a PID and then attempts to kill it! Also, you shouldn’t mix system with backticks (they are two ways of doing the same thing). Try something like this (untested):

sub kill_process
{
    print "Kill processes for the user? (y or n)?\n";
    my $ans = <>;

    while ($ans =~ /^Y/i)
    {
        print "Enter pid to kill:\n";
        my $pid = <>;
        chomp $pid;

        if (is_valid($pid))
        {
            `kill $pid`;
            print "Process $pid killed\n";
        }
        else
        {
            print "Process $pid is invalid\n";
        }

        print "Kill more processes for the user? (y or n)?\n";
        my $ans = <>;
    }
}
[download]

(You will need to implement sub is_valid too.)

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

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Re^2: Killing processes
by deyaneria (Acolyte) on Mar 20, 2015 at 16:17 UTC

I see what your saying but since I have previously listed all the processes running for the user, you are already pulling the pid from a valid list so I don't see the need for the is_valid, I know the code for that wasn't listed but it was a previous part of the code. So do I still need validate it? I guess i might need to in case of typo?

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Re^3: Killing processes

by Athanasius (Archbishop) on Mar 20, 2015 at 16:55 UTC

I guess i might need to in case of typo?

Yes, exactly. But since you already have an array of valid PIDs, it might be a better idea to change the logic of the subroutine and present each PID to the user instead. Like this:

my @pids = ...;

...

kill_processes(\@pids);

...

sub kill_processes
{
    my $pids = shift;

    for my $pid (@$pids)
    {
        print "Kill process $pid? ([y]es, [n]o, [q]uit)?\n";
        my $ans = <>;

        last if     $ans =~ /^Q/i;
        next unless $ans =~ /^Y/i;

       `kill $pid`;
        print "Process $pid killed\n";
    }
}
[download]

Using this approach there is no possibility of a user-input typo. And as a bonus, the loop logic is simpler.

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

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[d/l]

Re^4: Killing processes

by deyaneria (Acolyte) on Mar 20, 2015 at 17:19 UTC

Thanks you guys are amazing...I love the fact I can ask here when my teacher can't seem to understand the issue:)

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