getprotobynumber(3)					     Library Functions Manual					       getprotobynumber(3)

NAME

       getprotobynumber, getprotobynumber_r - Get a protocol entry by number

LIBRARY

       Standard C Library (libc.so, libc.a)

SYNOPSIS

       #include <netdb.h>
       struct protoent *getprotobynumber(      int num);

       [Tru64  UNIX]  The following obsolete function is supported in order to maintain backward compatibility with previous versions of the oper-
       ating system.  You should not use it in new designs.  int getprotobynumber_r(	  int num,	struct protoent *proto,       struct  pro-
       toent_data *proto_data);

STANDARDS

       Interfaces documented on this reference page conform to industry standards as follows:

       getprotobyname():  XNS4.0

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

PARAMETERS

       Specifies the protocol number.

	      [Tru64  UNIX]  For  getprotobynumber_r()	only, this points to the protoent structure.  The netdb.h header file defines the protoent
	      structure.  [Tru64 UNIX]	For getprotobynumber_r() only, this is data for the protocols database.  The netdb.h header  file  defines
	      the protoent_data structure.

DESCRIPTION

       The getprotobynumber() function returns a pointer to a structure of type protoent. Its members specify data in fields from a record line in
       either the local /etc/protocols file or NIS distributed network protocols database file. To determine which file or files to search, and in
       which order, the system uses the switches in the /etc/svc.conf file.  The netdb.h header file defines the protoent structure.

       The  getprotobynumber() function searches the network protocols database file sequentially until a match with the num parameter occurs. The
       num parameter must specify the official protocol number. When EOF (End-Of-File) is reached without a match, a null pointer is  returned	by
       this function.

       When using the getprotobynumber() function, use the endprotoent() function to close the protocols file.

NOTES

       The  getprotobynumber()	function  returns a pointer to thread-specific data.  Subsequent calls to this or a related function from the same
       thread overwrite this data.

       [Tru64 UNIX]  The getprotobynumber_r() function is an obsolete reentrant version of the getprotobynumber() function.  It  is  supported	in
       order  to  maintain backward compatibility with previous versions of the operating system and should not be used in new designs.  Note that
       you must zero-fill the proto_data structure before its first access by either the setprotoent_r() or getprotobynumber_r() functions.

RETURN VALUES

       Upon successful completion, the getprotobynumber() function returns a pointer to a protoent structure.  If it fails or reaches the  end	of
       the network protocols database file, it returns a null pointer.

       [Tru64  UNIX]  Upon  successful	completion,  the getprotobynumber_r() function stores the protoent structure in the location pointed to by
       proto, and returns a value of 0 (zero).	Upon failure, it returns a value of -1.

ERRORS

       Current industry standards do not define error values for the getprotobynumber() function.

       [Tru64 UNIX]  If any of the following conditions occurs, the getprotobynumber_r() function sets errno to the corresponding value:

       The proto_data or proto parameter is invalid.  The search failed.

       In addition, if the getprotobynumber() or getprotobynumber_r() function fails to open the file, it sets errno to indicate the cause of  the
       failure.

FILES

       The  DARPA Internet network protocols name database file. Each record in the file occupies a single line and has three fields: the official
       protocol name, the protocol number, and protocol aliases.  The database service selection configuration file.

RELATED INFORMATION

       Functions: getprotobyname(3), getprotoent(3), setprotoent(3), endprotoent(3).

       Files: protocols(4), svc.conf(4).

       Networks: nis_intro(7).

       Standards: standards(5).  delim off

															       getprotobynumber(3)