Re(3) shebang line

Not sure, exactly where I picked this stuff up; somewhere along the way, I suppose. You could probably use a decent UNIX and/or shell (sh/csh/ksh/bash/etc.) handbook. Check the library or bookstores, I suppose (can't remember any specific titles to recommend).

dmm

You can give a man a fish and feed him for a day ...
Or, you can teach him to fish and feed him for a lifetime

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Re: Re(3) shebang line by riffraff (Pilgrim) on Jan 04, 2002 at 04:56 UTC
Mostly correct, but with some caveats. First, when asked to execute a file, the kernel reads in the first 32 characters, minimum, not just the first two. Some of the older OS's only read the first 32 characters (POSIX spec, perhaps?), but I believe linux reads in 256. Then it checks if the first two characters if that line are #!, and if so, executes the program given by the path following the #!, up until the max characters that it read. Also, I believe it only looks at the first set of switches ('#!/usr/bin/perl -ixv' would get passed, but '#!/usr/bin/perl -i -x -v' would get passed as '#!/usr/bin/perl -i'). There's a little bit more to it, but those are the basics. update: Disregard this. If I would have just looked around a bit, I would have noticed that everybody else basically said the same thing...	[reply]

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Re: Re(3) shebang line
by riffraff (Pilgrim) on Jan 04, 2002 at 04:56 UTC

First, when asked to execute a file, the kernel reads in the first 32 characters, minimum, not just the first two. Some of the older OS's only read the first 32 characters (POSIX spec, perhaps?), but I believe linux reads in 256. Then it checks if the first two characters if that line are #!, and if so, executes the program given by the path following the #!, up until the max characters that it read. Also, I believe it only looks at the first set of switches ('#!/usr/bin/perl -ixv' would get passed, but '#!/usr/bin/perl -i -x -v' would get passed as '#!/usr/bin/perl -i').

There's a little bit more to it, but those are the basics.

update: Disregard this. If I would have just looked around a bit, I would have noticed that everybody else basically said the same thing...

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