Ok, got it now, and it works properly :)

unless (defined ($pid = fork)) 
{
    die "cannot fork: $!";
}

unless ($pid)  
{
    my @args=();
    @args=("$pipeline/EXE/searchXY", "-5", "UEB2K005I", "locate", "234
+", "156", "4", "Print");
    system(@args);
    exit;                        # the child stops here
}

open(FIFO, "<$pipeline/OUT/locateXY");

my $line;
while ($line = <FIFO>)
{
    print "rep $line";
    #or whatever here
}
close(FIFO);
waitpid($pid, 0); #clean up
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Now I just need a good reference/tutorial on fork to understand this properly :)

P.S. At some points you may want to add the two following lines, at appropriate places, before and after you use the above code, respectively:

system "/usr/bin/mkfifo $pipeline/OUT/locateXY";

system "chmod 777 $pipeline/OUT/locateXY"; #as needed

system "rm $pipeline/OUT/locateXY"; #to clean up if required
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