Obtaining structure definitions using man pages

Question

Is it possible to view structure definitions using man pages the way we can see function definitions in UNIX?

For instance, for network programming, we use a structure called struct sockaddr_in . Is there anyway to see how sockaddr_in has been defined in the library using man pages?

Any help will be appreciated! Thanks!

Answer 1

For any given header:

echo '#include <netinet/in.h>' | gcc -E - | less

Which generates of relevant interest:

# 225 "/usr/include/netinet/in.h" 3 4
struct sockaddr_in
  {
    sa_family_t sin_family;
    in_port_t sin_port;
    struct in_addr sin_addr;


    unsigned char sin_zero[sizeof (struct sockaddr) -
      (sizeof (unsigned short int)) -
      sizeof (in_port_t) -
      sizeof (struct in_addr)];
  };

This can be done using any compiler with a preprocessor option (every C compiler I know of can do this).

Answer 2

It depends on the function. For example, you can get the definition of struct sockaddr by looking at the man page of bind(2).

Unfortunately, there's no man page specifically for struct sockaddr.

Other ways to get this information would be to search for it the appropriate header files.

Answer 3

man-pages is just a files written by human or generated by wish of human. Usually all related structures is mentioned in man-pages with functions they used with. Sometimes you can find pages for header-files ( time.h(0p) ). Sometimes there is pages for a whole libraries ( libsensors(3) ). Sometimes there is actual pages for structures ( XAnyEvent(3) ).

You may want to check apropos and whatis. Sometimes they able to find pages related with what you are looking for.