Ooot.   Page 92 of the Ram says it all - chomp and $_.
Mutter, mutter... too many books stacked on my desk... mumble, mumble...

1  #!/usr/bin/perl -w
2  use strict;
3
4  $file = "/path/file";
5  @lines = ();
6  open (<FH>, "< $file") or die "Cannot open $file for read: $!";
7  while (<FH>) {
8      chomp;
9      push (@lines, $_);
10      }
11 close FH or die "Cannot close $file: $!"; 
12
13 print join(',', @lines);    # now it works
[download]