getprotoent(3N) 														   getprotoent(3N)

NAME

       getprotoent(), getprotobynumber(), getprotobyname(), setprotoent(), endprotoent() - get, set, or end protocol entry

SYNOPSIS

   _XOPEN_SOURCE_EXTENDED only
DESCRIPTION

       The  and functions each return a pointer to a structure of type protoent containing the broken-out fields of a line in the network protocol
       data base,

       The members of this structure are:

	      The official name of the protocol.

	      A null-terminated list of alternate names for the protocol.

	      The protocol number.

       Functions behave as follows:

	      Reads the next line of the file, opening the file if necessary.

	      Opens and rewinds the file.
				  If the stayopen flag is non-zero, the protocol data base is not closed after each call to  (either  directly	or
				  indirectly through one of the other calls).

	      Closes the file.

	      Each sequentially searches from the beginning of the file until a matching
				  protocol  name  (among  either  the  official names or the aliases) or protocol number is found, or until EOF is
				  encountered.

       In a multithreaded application, and use thread-specific storage that is re-used in each call.  The return value should be unique  for  each
       thread and should be saved, if desired, before the thread makes the next call.

       For  enumeration  in multithreaded applications, the position within the enumeration is a process-wide property shared by all threads.  may
       be used in a multithreaded application, but resets the enumeration position for all threads.  enumerates protocol entries: successive calls
       to  will  return  either  successive protocol entries or NULL.  If multiple threads interleave calls to the threads will enumerate disjoint
       subsets of the protocol database.

       If the system is running the Network Information Service (NIS), and get the protocol information from the NIS server  (see  ypserv(1M)  and
       ypfiles(4)).

   Name Service Switch-Based Operation
       The  library  routines  and their reentrant counterparts, internally call the name service switch to access the "protocols" database lookup
       policy configured in the file (see nsswitch.conf(4)).  The lookup policy defines the order and the criteria of the supported name  services
       used to resolve protocol names and numbers.

RETURN VALUE

       and return a null pointer(0) on EOF or when they are unable to open

OBSOLESCENT INTERFACES

       The  above  reentrant  interfaces have been moved from to They are included to support existing applications and may be removed in a future
       release.  New multithreaded applications should use the regular APIs without

       The reentrant interfaces performs the same operation as their regular counterpart (those without the suffix.)  However, and  expect  to	be
       passed the address of a parameter and will store the address of the result at this supplied parameter.  An additional parameter, an address
       to struct protoent_data, which is defined in the file cannot be a NULL pointer.

       The reentrant routines return if the operation is unsuccessful, or, in the case of if the end of the services list has  been  reached.	is
       returned otherwise.

EXAMPLES

       The following code excerpt counts the number of protocols entries:

WARNINGS

       Programs  that  use  the  interfaces  described	in this manpage cannot be linked statically because the implementations of these functions
       employ dynamic loading and linking of shared objects at run time.

AUTHOR

       was developed by Sun Microsystems Inc.

FILES

SEE ALSO

       ypserv(1M), nsswitch.conf(4), protocols(4), ypfiles(4), thread_safety(5).

STANDARDS CONFORMANCE

																   getprotoent(3N)