Re^2: Windows run an exe print its output and cut it off after a time

[BrowserUk]

in reply to Re: Windows run an exe print its output and cut it off after a time
in thread Windows run an exe print its output and cut it off after a time

"Emulated" or not, alarm works fine on Windows. As do both forms of piped open:

C:\test>perl -E"alarm 5; say(),sleep(1) for 1 .. 10"
1
2
3
4
5
Terminating on signal SIGALRM(14)

C:\test>perl -E"$p=open I, '-|', 'ver'; say <I>"

Microsoft Windows [Version 6.0.6001]


C:\test>perl -E"$p=open O, '|-', 'find \"1\"'; say O for 1 .. 10"
1
10

[VinsWorldcom]

Well blow me down, BrowserUK is correct. I've never gotten alarm() to work reliably on Windows - perhaps because I'm not that versed in Signals and didn't know what I was doing or was trying on a system call without the eval/die as described in alarm; however, alarm() added in my original script works:

use strict;
use warnings;

my $pid = open(my $fileHandler, '-|', "./test.exe" );

my $DONE = 0;
$SIG{ALRM} = sub { $DONE = 1 };
alarm 2;

while (<$fileHandler>) {
    print "$_\r"; # \r to not overrun output screen buffer
    last if ($DONE)
}

print "\nTimeout! - Time to kill pid: $pid\n"

And the output

VinsWorldcom@C:\Users\VinsWorldcom\tmp> TimeThis test.pl

TimeThis :  Command Line :  test.pl
TimeThis :    Start Time :  Fri Oct 12 13:01:09 2012

114601
Timeout! - Time to kill pid: 4700

TimeThis :  Command Line :  test.pl
TimeThis :    Start Time :  Fri Oct 12 13:01:09 2012
TimeThis :      End Time :  Fri Oct 12 13:01:12 2012
TimeThis :  Elapsed Time :  00:00:02.454

[kcott]

I thought alarm did work fine but the OP wrote "... alarm is not working in windows.". As I don't have a Windows Perl in front of me, I checked the doco. I wasn't trying to make any point by using the word emulated - that's just what the doco says: "alarm Emulated using timers ...".

Scrolling down the perlport page a bit after reading about alarm, I came across the open entry by chance. It seems the doco is just wrong with respect to piped open. perlport says it's "unsupported"; perlfork says it's "not yet implemented".

Thanks for the example code.

[BrowserUk]

that's just what the doco says: "alarm Emulated using timers ...".

In the sense that the OS has neither a native alarm API nor *nix-style signals, it is emulated.

But then again, under modern versions of *nix including linux, the original form of alarm is also "emulated with timers", so not so different.

perlport says it's "unsupported"; perlfork says it's "not yet implemented".

A lot of those more obscure docs have never been updated to reflect the current state of play unfortunately.