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man: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
     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).
     allbox;  lbw15  lb  lbw25  l l l.  Interface Attribute Value T{ getser-
     vent() T}   Thread safety  T{ MT-Unsafe race:servent
     race:serventbuf locale T} T{ getservbyname() T}   Thread safety  T{ MT-
     Unsafe race:servbyname
     locale   T}   T{   getservbyport()   T}   Thread  safety  T{  MT-Unsafe
     race:servbyport
     locale T} T{ setservent(),
     endservent() T}   Thread safety  T{ MT-Unsafe race:servent
     locale T}
     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 4.16 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)

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