17 Dec
2011
17 Dec
'11
2:07 p.m.
>> How do you think an unix shell is starting an
excecutable file and
>> trough wich mechanism it knows what todo with an perl script, an
>> shell script, an C-shell scipt, [...]
>> In unix a shell is doing this,
> Actually, in the Unices I know well enough to know
where that is
> done, it's the kernel that does that, not the shell.
Yes, the shell is doing this trough the system calls.
No, I mean the kernel is doing it inside execve(). On the Unices I
know well enough to talk about in this regard, recognition of #!, of
ELF vs a.out vs whatever, etc, is done entirely in the kernel as part
of execing the executable. The shell is totally out of the loop.
[...] but the system call is not using any naming
conventions of file
extensions to do this.
True. It's entirely driven off file contents. I don't know of any OS
where execve() pays any attention to what's in the pathname beyond
handing it to the filesystem layer to locate the relevant file.
I usually have
to end up running it through a text-to-PS filter
because the printing subsystem insists on treating everything that
looks enough like PostScript as PostScript. :(
Oh man. Could you please take a
look to the print filters in the
printing system? This again has nothing todo wit unix as such.