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
   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    │
   │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
   occur.

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 4.09 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/.

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