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 connection 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  5.10  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                                                2020-12-21                                     GETPROTOENT(3)