man perlrun

-p   causes Perl to assume the following loop around your program, which makes it iterate over filename arguments somewhat like sed:
    LINE:
       while (<>) {
           ...             # your program goes here
        } continue {
        print or die "-p destination: $!\n";
        }

   If a file named by an argument cannot be opened for some reason, Perl warns you about it, and moves on to the next file.  
   Note that the lines are printed automatically.  An error occurring during printing is treated as fatal.  
   To suppress printing use the -n switch.  A -p overrides a -n switch.

   "BEGIN" and "END" blocks may be used to capture control before or after the implicit loop, just as in awk.
....
-0[octal/hexadecimal]
   specifies the input record separator ($/) as an octal or hexadecimal number.  
   If there are no digits, the null character is the separator.  
   Other switches may precede or follow the digits.  For example, if you have a version of find which 
   can print filenames terminated by the null character, you can say this:

                find . -name ’*.orig’ -print0 │ perl -n0e unlink

   The special value 00 will cause Perl to slurp files in paragraph mode.  
   The value 0777 will cause Perl to slurp files whole because there is no legal byte with that value.

   If you want to specify any Unicode character, use the hexadecimal format: "-0xHHH...", 
   where the "H" are valid hexadecimal digits.  (This means that you cannot use
   the "-x" with a directory name that consists of hexadecimal digits.)

....
-e commandline
    may be used to enter one line of program.  If -e is given, Perl will not look for a filename in the argument list.  
    Multiple -e commands may be given to build up a multi-line script.  
   Make sure to use semicolons where you would in a normal program.