> shebang (n.) - 1862, "hut, shed, shelter," popularized among soldiers in the U.S. Civil War, but like other Civil War slang (such as skedaddle) of uncertain origin.
> Perhaps an alteration of shebeen (q.v.), but shebang in the sense "tavern," a seemingly necessary transitional sense, is not attested before 1878 and shebeen seems to have been not much used in the U.S. Bartlett's 1877 edition describes it as "A strange word that had its origin during the late civil war. It is applied alike to a room, a shop, or a hut, a tent, a cabin; an engine house."
> Phrase the whole shebang first recorded 1869, but relation to the earlier use of the word is obscure. Either or both senses also might be mangled pronunciations of French char-à-banc, a bus-like wagon with many seats.
> Perhaps an alteration of shebeen (q.v.), but shebang in the sense "tavern," a seemingly necessary transitional sense, is not attested before 1878 and shebeen seems to have been not much used in the U.S. Bartlett's 1877 edition describes it as "A strange word that had its origin during the late civil war. It is applied alike to a room, a shop, or a hut, a tent, a cabin; an engine house."
> Phrase the whole shebang first recorded 1869, but relation to the earlier use of the word is obscure. Either or both senses also might be mangled pronunciations of French char-à-banc, a bus-like wagon with many seats.
https://www.etymonline.com/word/shebang