The one embedded in the source code is an octal number string literal to Perl. The other is a string to Perl, as it comes from @ARGV.

If you want to treat incoming parameters as octal, see the oct function.

Updated: s/number string/number literal/, suggested by LanX

1. a scalar variable can be a number or a string (or a reference ...)
2. There are various literal notations in code
3. literals like "txt" , 'txt' , q(txt) , ... will produce the same string txt
4. literals like 016 , 0xE , 14 will produce the same number (well integer) 14
5. a string might look like a literal notation of a number like "016" , but literal notation inside strings will not be interpreted
6. an implicit string to number conversion will always be decimal, hence "016" + 3  == 19 not 17
7. if you want another base, you need to convert the string explicitly by yourself
8. one (dangerous) way is eval("016") == 14

I hope it's clearer now.

Arguments are received as strings. The second is equivalent to

perl -le '$n="0666"; print $n'
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perl -le '$n=q(0666); print $n'
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