is a magic file (specifically, a .COM file). It is, essentially, DOS.

Unlike *nix, DOS's commands are embedded in Want to hack dir so it replaces all instances of e with 3, so you can be a h4x0r? Tough luck. You have to modify to do that, and ain't open source.

On the other hand, is rather efficient in that, along with a few helper files (most notably CONFIG.SYS, and AUTOEXEC.BAT), it provides a basic OS with scripting (sort of) in less than 300k of memory. Or, it used to. Nowadays, you'd better have extended memory set up right if you want to sneeze.

An excellent example of monolithic coding.

From wharfinger: not *all* dos commands are in; just most. and it runs like-named batch files before built-ins, if the .bat is in %path%. Sorry, wharfinger, I removed your mandatory microsoft rant. ;)