> for instance you can use : instead of #! and, if I remember correctly, the OS will use "the default shell" when I learned unix around 1980, you had to start

> for instance you can use : instead of #! and, if I remember correctly, the OS will use "the default shell" when I learned unix around 1980, you had to start a shell script file with a single # on a line by itself, and there was no bang option... but I want to say there was a way to select sh vs csh, though I can't recall it... maybe you had to start with a couple lines of Bourneshell, and that part would relauch csh on the same file. can't remember though. A dozen years later that was a common technique to launch perl scripts tho I don't recall why.