$ ls -l pm_user_input_file
ls: pm_user_input_file: No such file or directory

##</code><code>##

$ perl -Mstrict -Mwarnings -E '
    use autodie qw{:all};
    open my $fh, q{>}, q{pm_user_input_file};
    while (<>) {
        print {$fh} $_;
    }
'
1,2,3
q,w,e
a,s,d
z,x,c

##</code><code>##

$ ls -l pm_user_input_file
-rw-r--r--  1 ken  staff  24 19 Jun 23:49 pm_user_input_file

##</code><code>##

$ cat pm_user_input_file
1,2,3
q,w,e
a,s,d
z,x,c