getservent(3)              Library Functions Manual              getservent(3)

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.1-2008.

HISTORY
       POSIX.1-2001, 4.3BSD.

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

Linux man-pages 6.7               2023-10-31                     getservent(3)