NAME

       getservent, getservbyname, getservbyport, setservent, endservent - get service entry

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <netdb.h>

       struct servent *getservent(void);

       struct servent *getservbyname(const char *name, const char *proto);
       struct servent *getservbyport(int port, const char *proto);

       void setservent(int stayopen);
       void endservent(void);

DESCRIPTION

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

       The  getservbyname()  function returns a servent structure for the entry from the database
       that matches the service name using protocol proto.  If proto is NULL, any  protocol  will
       be matched.  A connection is opened to the database if necessary.

       The  getservbyport()  function returns a servent structure for the entry from the database
       that matches the port port (given in network byte order) using protocol proto.   If  proto
       is  NULL,  any  protocol  will  be  matched.   A  connection  is opened to the database if
       necessary.

       The setservent() 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 getserv*() functions.

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

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

           struct servent {
               char  *s_name;       /* official service name */
               char **s_aliases;    /* alias list */
               int    s_port;       /* port number */
               char  *s_proto;      /* protocol to use */
           }

       The members of the servent structure are:

       s_name The official name of the service.

       s_aliases
              A NULL-terminated list of alternative names for the service.

       s_port The port number for the service given in network byte order.

       s_proto
              The name of the protocol to use with this service.

RETURN VALUE

       The getservent(), getservbyname(), and getservbyport() functions return  a  pointer  to  a
       statically  allocated servent structure, or NULL if an error occurs or the end of the file
       is reached.

FILES

       /etc/services
              services database file

ATTRIBUTES

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

       ┌────────────────┬───────────────┬────────────────────────────────────────────────────────┐
       │Interface       │ Attribute     │ Value                                                  │
       ├────────────────┼───────────────┼────────────────────────────────────────────────────────┤
       │getservent()    │ Thread safety │ MT-Unsafe race:servent race:serventbuf locale          │
       ├────────────────┼───────────────┼────────────────────────────────────────────────────────┤
       │getservbyname() │ Thread safety │ MT-Unsafe race:servbyname locale                       │
       ├────────────────┼───────────────┼────────────────────────────────────────────────────────┤
       │getservbyport() │ Thread safety │ MT-Unsafe race:servbyport locale                       │
       ├────────────────┼───────────────┼────────────────────────────────────────────────────────┤
       │setservent(),   │ Thread safety │ MT-Unsafe race:servent locale                          │
       │endservent()    │               │                                                        │
       └────────────────┴───────────────┴────────────────────────────────────────────────────────┘
       In  the  above  table,  servent  in  race:servent  signifies  that if any of the functions
       setservent(), getservent(), or endservent() are used in parallel in different threads of a
       program, then data races could occur.

STANDARDS

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

SEE ALSO

       getnetent(3), getprotoent(3), getservent_r(3), services(5)