netbsd man page for getprotobynumber

GETPROTOENT(3)						   BSD Library Functions Manual 					    GETPROTOENT(3)

NAME
     getprotoent, getprotobynumber, getprotobyname, setprotoent, endprotoent -- get protocol entry

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <netdb.h>

     struct protoent *
     getprotoent();

     struct protoent *
     getprotobyname(const char *name);

     struct protoent *
     getprotobynumber(int proto);

     void
     setprotoent(int stayopen);

     void
     endprotoent(void);

DESCRIPTION
     The getprotoent(), getprotobyname(), and getprotobynumber() functions each return a pointer to an object with the following structure con-
     taining the broken-out fields of a line in the network protocol data base, /etc/protocols.

	   struct  protoent {
		   char    *p_name;	   /* official name of protocol */
		   char    **p_aliases;    /* alias list */
		   int	   p_proto;	   /* protocol number */
	   };

     The members of this structure are:

	   p_name     The official name of the protocol.

	   p_aliases  A zero terminated list of alternative names for the protocol.

	   p_proto    The protocol number.

     The getprotoent() function reads the next line of the file, opening the file if necessary.

     The setprotoent() function opens and rewinds the file.  If the stayopen flag is non-zero, the net data base will not be closed after each
     call to getprotobyname() or getprotobynumber().

     The endprotoent() function closes the file.

     The getprotobyname() function and getprotobynumber() sequentially search from the beginning of the file until a matching protocol name or
     protocol number is found, or until EOF is encountered.

RETURN VALUES
     Upon success, getprotoent(), getprotobyname(), and getprotobynumber() return a pointer to the protoent structure as described above.  A NULL
     pointer is returned on EOF or error.

FILES
     /etc/protocols

SEE ALSO
     protocols(5)

HISTORY
     The getprotoent(), getprotobynumber(), getprotobyname(), setprotoent(), and endprotoent() functions appeared in 4.2BSD.

BUGS
     These functions use a static data space; if the data is needed for future use, it should be copied before any subsequent calls overwrite it.
     Only the Internet protocols are currently understood.

BSD
								   July 15, 2011							       BSD