Perl how to properly handle System Commands (including Timeout with Kill & capture of RC/STDERR/STDOUT)

Question

From a Perl script I want to execute various system commands and process the output in my script.

The script will be run automatically, so I want to make sure that no commands are hanging etc.

I'm open to any kind of feedback.

My requirements for the command execution:

• Timeout -> If command runs longer than XX Seconds, it should kill its process(es)
• If command returns information, it should not have to wait for end of timeout
• I want to capture the exit status, STDERR, STDOUT in the script.

Here is an example I worked out from an other stackoverflow question: Kill a hung child process

What's not working for me at the moment:

• cannot capture exit status of executed command
• cannot capture STDERR of executed command

Code:

my $cmd = "sleep 15"; # other tests i use -> "echo bla" and "alkjdsf"
my $TIMEOUT = 10;

my $pid = open my $proc, '-|', "$cmd";

if (fork() == 0) {
    my $poor_mans_alarm = "sleep 1,kill 0,$pid ||exit for 1..$TIMEOUT;kill 9,$pid";
    # run poor man's alarm in a background process
    exec($^X, '-e', "$poor_mans_alarm");
}

my $process_output = "";
while (<$proc>) {
   $process_output .= $_;
}

If you either have a trick for this code or recommend a completely different solution, let me know.

Thanks and cheers

---

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Addition:

Got a working Example with IPC::Open3, But for future reader please Check out IPC::Run which has a Timeout Functionality included, as mentioned by James Green.

Working example with IPC::Open3:

my $pid = open3(\*WRITE, \*READ,\*ERROR,"$command");

if (fork() == 0) {
    my $poor_mans_alarm = "sleep 1,kill 0,$pid ||exit for 1..10;kill 9,$pid";
    # run poor man's alarm in a background process
    exec($^X, '-e', "$poor_mans_alarm");
}


# get all the STDOUT and STDERR from the Child.
while (<READ>) {
   $output .= $_;
}

while (<ERROR>) {
   $output .= $_;
}

waitpid($pid, 0);
if ($?) {
    $rc = $? >> 8;
    if ($rc != 1){
        print "Some error $?\n";
    }
}

Answer 1

It looks like IPC::Run provides pretty much everything you're after, including timeouts and capture of both STDOUT and STDERR. Docs are at https://metacpan.org/pod/IPC::Run including some usage examples.