So long story short, I'm trying to run a linux perl script in Windows ( with few modifications ).

On Unix it works just fine, but on Windows I come to the conclusion that calling for system doesn't work the same as on Unix and so it doesn't create multiple processes.

Below is the code :

use strict;
use warnings;
open (FIN, 'words.txt'); while (<FIN>) {
   chomp;
   my $line = $_;
   system( "perl script.pl $line &" );
   
}
close (FIN);

So basically, I have 5 different words in "words.txt" which I want each and every one to be used one by one when calling for script.pl , which means :

word1 script.pl
word2 script.pl
word3 script.pl
etc

As of now it opens just the first word in words.txt and it loops with that one only. As I said, on Unix it works perfectly, but not on Windows.

I've tried to use "start" system( "start perl script.pl $line &" ); and it works...except it opens 5 additional CMDs to do the work. I want it to do the work on the same window.

If anyone has any idea how this can work on window, i'll really appreciate it.

Thanks!

CodePudding user response：

According to perlport :

system

(Win32) [...] system(1, @args) spawns an external process and immediately returns its process designator, without waiting for it to terminate. Return value may be used subsequently in wait or waitpid. Failure to spawn() a subprocess is indicated by setting $? to 255 << 8. $? is set in a way compatible with Unix (i.e. the exit status of the subprocess is obtained by $? >> 8, as described in the documentation).

I tried this:

use strict;
use warnings;
use feature qw(say);
say "Starting..";
my @pids;
for my $word (qw(word1 word2 word3 word3 word5)) {
    my $pid = system(1, "perl script.pl $word" );
    if ($? == -1) {
        say "failed to execute: $!";
    }
    push @pids, $pid; 
}

#wait for all children to finish
for my $pid (@pids) {
    say "Waiting for child $pid ..";
    my $ret = waitpid $pid, 0;
    if ($ret == -1) {
        say " No such child $pid";
    }
    if ($? & 127) {
        printf " child $pid died with signal %d\n", $? & 127;
    }
    else {
        printf " child $pid exited with value %d\n", $? >> 8;
    }
}
say "Done.";

With the following child script script.pl :

use strict;
use warnings;
use feature qw(say);
say "Starting: $$";
sleep 2 int(rand 5);
say "Done: $$";
sleep 1;
exit int(rand 10);

I get the following output:

Starting..
Waiting for child 7480 ..
Starting: 9720
Starting: 10720
Starting: 9272
Starting: 13608
Starting: 13024
Done: 13608
Done: 10720
Done: 9272
Done: 9720
Done: 13024
 child 7480 exited with value 9
Waiting for child 13344 ..
 child 13344 exited with value 5
Waiting for child 17396 ..
 child 17396 exited with value 3
Waiting for child 17036 ..
 child 17036 exited with value 6
Waiting for child 17532 ..
 child 17532 exited with value 8
Done.

Seems to work fine..

CodePudding user response：

You can use Win32::Process to get finer control over creating a new process than system gives you on Windows. In particular, the following doesn't create a new console for each process like using system("start ...") does:

#!/usr/bin/env perl
use warnings;
use strict;
use feature qw/say/;
# Older versions don't work with an undef appname argument.
# Use the full path to perl.exe on them if you can't upgrade
use Win32::Process 0.17; 

my @lines = qw/foo bar baz quux/; # For example instead of using a file
my @procs;
for my $line (@lines) {
    my $proc;
    if (!Win32::Process::Create($proc, undef, "perl script.pl $line", 1,
                                NORMAL_PRIORITY_CLASS, ".")) {
        $_->Kill(1) for @procs;
        die "Unable to create process: $!\n";
    }
    push @procs, $proc;
}

$_->Wait(INFINITE) for @procs;
# Or
# use Win32::IPC qw/wait_all/;
# wait_all(@procs);

As Yet Another Way To Do It, the start command takes a /b option to not open a new command prompt.

system("start /b perl script.pl $line");