ntpdate: add page (#6856)

pages/linux/ntpdate.md

@@ -0,0 +1,20 @@
+# ntpdate
+
+> Synchronize and set the date and time via NTP.
+> More information: <http://support.ntp.org/documentation>.
+
+- Synchronize and set date and time:
+
+`sudo ntpdate {{host}}`
+
+- Query the host without setting the time:
+
+`ntpdate -q {{host}}`
+
+- Use an unprivileged port in case a firewall is blocking privileged ports:
+
+`sudo ntpdate -u {{host}}`
+
+- Force time to be stepped using `settimeofday` instead of `slewed`:
+
+`sudo ntpdate -b {{host}}`