1 .\" Copyright 2003 walter harms (walter.harms@informatik.uni-oldenburg.de)
3 .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
4 .\" Distributed under GPL
7 .\" Modified 2003-04-04 Walter Harms
8 .\" <walter.harms@informatik.uni-oldenburg.de>
10 .\" Slightly polished, aeb, 2003-04-06
12 .TH RTIME 3 2014-05-28 "GNU" "Linux Programmer's Manual"
14 rtime \- get time from a remote machine
17 .B "#include <rpc/auth_des.h>"
19 .BI "int rtime(struct sockaddr_in *" addrp ", struct rpc_timeval *" timep ,
20 .BI " struct rpc_timeval *" timeout );
23 This function uses the Time Server Protocol as described in
24 RFC\ 868 to obtain the time from a remote machine.
26 The Time Server Protocol gives the time in seconds since
27 00:00:00 UTC, 1 Jan 1900,
28 and this function subtracts the appropriate constant in order to
29 convert the result to seconds since the
30 Epoch, 1970-01-01 00:00:00 +0000 (UTC).
34 is non-NULL, the udp/time socket (port 37) is used.
35 Otherwise, the tcp/time socket (port 37) is used.
37 On success, 0 is returned, and the obtained 32-bit time value is stored in
39 In case of error \-1 is returned, and
43 All errors for underlying functions
53 The number of returned bytes is not 4.
56 The waiting time as defined in timeout has expired.
58 .SS Multithreading (see pthreads(7))
61 function is thread-safe.
63 Only IPv4 is supported.
67 versions support only TCP.
68 Try the example program with
72 Libc5 uses the prototype
75 int rtime(struct sockaddr_in *, struct timeval *, struct timeval *);
81 .IR <rpc/auth_des.h> .
84 in glibc 2.2.5 and earlier does not work properly on 64-bit machines.
86 This example requires that port 37 is up and open.
88 that the time entry within
92 The program connects to a computer called "linux".
93 Using "localhost" does not work.
94 The result is the localtime of the computer "linux".
102 #include <rpc/auth_des.h>
105 static int use_tcp = 0;
106 static char *servername = "linux";
111 struct sockaddr_in name;
112 struct rpc_timeval time1 = {0,0};
113 struct rpc_timeval timeout = {1,0};
114 struct hostent *hent;
117 memset(&name, 0, sizeof(name));
119 hent = gethostbyname(servername);
120 memcpy(&name.sin_addr, hent\->h_addr, hent\->h_length);
122 ret = rtime(&name, &time1, use_tcp ? NULL : &timeout);
124 perror("rtime error");
126 time_t t = time1.tv_sec;
127 printf("%s\\n", ctime(&t));
139 This page is part of release 3.79 of the Linux
142 A description of the project,
143 information about reporting bugs,
144 and the latest version of this page,
146 \%http://www.kernel.org/doc/man\-pages/.