getservbyport

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

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

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  data-
       base  (see  services(5)) and returns a servent structure containing the
       broken-out fields from the entry.  A connection is opened to the  data-
       base 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 or-
       der) 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  at-
       tributes(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    |
       |endservent()    |               | locale                    |
       +----------------+---------------+---------------------------+
       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 oc-
       cur.

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

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

COLOPHON
       This page is part of release 5.05 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                     GETSERVENT(3)