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Why does the "she-bang" begin with a #!, like #!/bin/bash? I have always accepted that this how it is done, but is there a reason behind it?

Why start with #; isn't that usually a comment? Or is it the point that it should be comment?

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Wikipedia has a fairly detailed history of #! (as much as dmr remembers…), including an explanation of why the # (yes, the line had to be ignored by existing shells). – Gilles Jul 13 '11 at 13:08
Missed to check wikipedia :) – Johan Jul 13 '11 at 13:30
I just wish the shells were smart enough to strip an extraneous CR/LF if it is there... ;) – Aaron D. Marasco Jul 14 '11 at 1:02

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Typically shebang refers to just the #! (! is typically called "bang", and it looks like "she" is a corruption of either "SHArp" or "haSH" for #) -- the whole line is called a shebang line

It does intentionally start with a comment character for backwards-compatibility with things that don't know how to handle it; the ! is presumably just to distinguish it from a random comment starting the file, so a file that begins with # this is my script! doesn't try to run the this is my script! interpreter

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Bang ! is often used in other contexts to indicate a command to be executed. For example in vim or other programs with their own command lines, bang is often the escape character that makes them run the command in a system shell instead of their internal interface. – Caleb Jul 27 '11 at 11:32
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It needs to be a comment because only this way it will also work to run a script like "interpretername scriptname". I do not know about the origin of the "!".

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Even if you just run ./scriptname, the interpreter still sees the she-bang line, so it still needs to be a comment. – psusi Jul 13 '11 at 18:18
Or to be more detailed: the shebang: '#!' is designed not to be seen by the interpreter -- thus it must start with the comment char '#'. Instead, it is 'seen' (and interpreted) by the kernel 'exec[lv]*' set of system calls. – arielf May 13 at 20:12

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