The Collaborative International Dictionary of English v.0.48:

Shebang \She*bang"\, n. [Cf. Shebeen.]
   1. A jocosely depreciative name for a dwelling or shop; a
      primitive dwelling; a shanty. [Slang, U.S.]
      [1913 Webster]

   2. The structure of an object, process, organization, or
      anything viewed as complicated; -- used primarily in the
      phrase

   the whole shebang; as, it comes with unnecessary frills,
      but you have to buy the whole shebang. [informal]
      [PJC]

   3. (computers) [Possibly derived from shell bang; the
      character ! is referred to in some computer contexts as
      bang.] The character sequence #!, which frequently begins
      shell scripts in a Unix system.
      [PJC]