unistd.h

[RobinVossen]

Hello,

I got quite an easy question I guess.

Does unistd.h declare functions in the kernel or in the stdclib? Or in any other C file.
I need to know from the inside how some of the functions work.

So where does unistd redirect to?

Thanks

Cheers,
Robin

[Schmidt]

Hello,

I got quite an easy question I guess.

Does unistd.h declare functions in the kernel or in the stdclib? Or in any other C file.
I need to know from the inside how some of the functions work.

So where does unistd redirect to?

Thanks

Cheers,
Robin

as I remember, linux kernel uses libc itself...) but in any case, if you want to know how a function works, you can search it in kernel source, or just compile kernel in debug mode and use gcc by your hands I think it could be useful to read kernel docs too (something about unistd... Or just try 'man unistd' command ).

[Cabhan]

I don't fully understand your question.

unistd.h is a part of glibc, which is the GNU implementation of the C library. glibc is an external library loaded into pretty much every executable (ones compiled from C, at least), but it is not included in the kernel. Kernel programming uses a separate set of libraries that are kernel-specific, and kernel programming cannot use normal libc functions.

[Rubberman]

I don't fully understand your question.

unistd.h is a part of glibc, which is the GNU implementation of the C library. glibc is an external library loaded into pretty much every executable (ones compiled from C, at least), but it is not included in the kernel. Kernel programming uses a separate set of libraries that are kernel-specific, and kernel programming cannot use normal libc functions.

While true that glibc and libc are not used directly by the kernel, the kernel has it's own version of unistd.h and other common headers in linux-src-dir/include/linux, so in kernel code you would #include <linux/unistd.h> in order to get unistd.h functions. In any case, do read the docs.

[RobinVossen]

Thanks all,
I managed to override a default function from unistd.h

Thanks all real great =)