I like the opportunity to get fancy, but I noticed an odd reaction of the sysread(). Using: 

my $result;
while (select my $rd = $rin, undef, undef, 60) {
    my $bytes = sysread *CMD, substr($result, -1), 4096;
    last if 1 > $bytes;
}

...

print "I am finished with my task.  My results are: \n";
print $result."\n";

[download]
My output is: 

I am finished with my task.  My result are:

Pinging google.com [216.239.37.99] with 32 bytes of data:
Reply from 216.239.37.99:bytes=32 time=36ms TTL=244

Ping statistics for 216.239.37.99:
    Packets: Sent = 15, Received = 15, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 36ms, Maximum = 37ms, Average = 36ms

[download]
What happened to all of the other lines from the ping (should be 15 result lines)? I would expect it to be: 

I am finished with my task.  My result are:

Pinging google.com [216.239.37.99] with 32 bytes of data:

Reply from 216.239.37.99: bytes=32 time=37ms TTL=244
Reply from 216.239.37.99: bytes=32 time=36ms TTL=244
Reply from 216.239.37.99: bytes=32 time=36ms TTL=244
Reply from 216.239.37.99: bytes=32 time=36ms TTL=244
Reply from 216.239.37.99: bytes=32 time=36ms TTL=244
Reply from 216.239.37.99: bytes=32 time=36ms TTL=244
Reply from 216.239.37.99: bytes=32 time=36ms TTL=244
Reply from 216.239.37.99: bytes=32 time=36ms TTL=244
Reply from 216.239.37.99: bytes=32 time=36ms TTL=244
Reply from 216.239.37.99: bytes=32 time=36ms TTL=244
Reply from 216.239.37.99: bytes=32 time=36ms TTL=244
Reply from 216.239.37.99: bytes=32 time=36ms TTL=244
Reply from 216.239.37.99: bytes=32 time=37ms TTL=244
Reply from 216.239.37.99: bytes=32 time=37ms TTL=244
Reply from 216.239.37.99: bytes=32 time=37ms TTL=244

Ping statistics for 216.239.37.99:
    Packets: Sent = 15, Received = 15, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 36ms, Maximum = 37ms, Average = 36ms

[download]
What happens that makes the $result apparently overwrite the output of the *CMD? I would still want to output the live results and set the variable, so would it be best to use the concatenation? I can't print $result in the loop, since that would contain all of the output, not just that loop's progress.

Also, why is the sysread() length set to 4096. Does that have a significant value?

Thanks!

In reply to Re^4: SIGINT and system calls by Anonymous Monk
in thread SIGINT and system calls by Anonymous Monk

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