You could do something like this:
#!/usr/bin/perl -w
use strict;
my @fh;
# open all files
for my $i (0..$#ARGV) {
open $fh[$i], "<", $ARGV[$i] or die $!;
}
while (1) {
my @lines;
# read one line from each file
push @lines, scalar readline $fh[$_] for 0..$#ARGV;
last unless defined $lines[0];
chomp @lines;
print join(",", @lines), "\n";
}
$ ./950649.pl infile1 infile2 infile3 ... > outfile
(Note that you have to use readline with "complex" file handle expressions like $fh[$i], as <$fh[$i]> wouldn't work here.)