GETPROTOENT(3)						     Linux Programmer's Manual						    GETPROTOENT(3)

NAME

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

SYNOPSIS

       #include <netdb.h>

       struct protoent *getprotoent(void);

       struct protoent *getprotobyname(const char *name);

       struct protoent *getprotobynumber(int proto);

       void setprotoent(int stayopen);

       void endprotoent(void);

DESCRIPTION

       The  getprotoent() function reads the next entry from the protocols database (see protocols(5)) and returns a protoent structure containing
       the broken-out fields from the entry.  A connection is opened to the database if necessary.

       The getprotobyname() function returns a protoent structure for the entry from the database that matches the protocol name name.	A  connec-
       tion is opened to the database if necessary.

       The  getprotobynumber()	function  returns a protoent structure for the entry from the database that matches the protocol number number.  A
       connection is opened to the database if necessary.

       The setprotoent() function opens a connection to the database, and sets the next entry to the first entry.  If stayopen	is  nonzero,  then
       the connection to the database will not be closed between calls to one of the getproto*() functions.

       The endprotoent() function closes the connection to the database.

       The protoent structure is defined in <netdb.h> as follows:

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

       The members of the protoent structure are:

       p_name The official name of the protocol.

       p_aliases
	      A NULL-terminated list of alternative names for the protocol.

       p_proto
	      The protocol number.

RETURN VALUE

       The  getprotoent(),  getprotobyname()  and getprotobynumber() functions return a pointer to a statically allocated protoent structure, or a
       null pointer if an error occurs or the end of the file is reached.

FILES

       /etc/protocols
	      protocol database file

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       +-------------------+---------------+------------------------------+
       |Interface	   | Attribute	   | Value			  |
       +-------------------+---------------+------------------------------+
       |getprotoent()	   | Thread safety | MT-Unsafe race:protoent	  |
       |		   |		   | race:protoentbuf locale	  |
       +-------------------+---------------+------------------------------+
       |getprotobyname()   | Thread safety | MT-Unsafe race:protobyname   |
       |		   |		   | locale			  |
       +-------------------+---------------+------------------------------+
       |getprotobynumber() | Thread safety | MT-Unsafe race:protobynumber |
       |		   |		   | locale			  |
       +-------------------+---------------+------------------------------+
       |setprotoent(),	   | Thread safety | MT-Unsafe race:protoent	  |
       |endprotoent()	   |		   | locale			  |
       +-------------------+---------------+------------------------------+
       In the above table, protoent in race:protoent signifies that if any of the functions setprotoent(),  getprotoent(),  or	endprotoent()  are
       used in parallel in different threads of a program, then data races could occur.

CONFORMING TO

       POSIX.1-2001, POSIX.1-2008, 4.3BSD.

SEE ALSO

       getnetent(3), getprotoent_r(3), getservent(3), protocols(5)

COLOPHON

       This  page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

GNU
								    2017-09-15							    GETPROTOENT(3)