print "Enter a directory´s path to work with all files in a folder or a single file path\n\n";
chomp(my $input = <STDIN>);

if ($input =~ /./){      ### attempt of recognizing a file extention

... process file

}elsif ($input =~ /[^.]/){  #### attempt of recognizing just a folder but i know it wont work always

... process folder

}

##</code><code>##

print "Enter a directory´s path to work with all files in a folder or a single file path\n\n";
chomp(my $input = <STDIN>);

if (-f $input){      # $input is the name of an existing file

... process file

}elsif (-d $input){  # $input is the name of an existing folder

... process folder

}