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authorDavid Oberhollenzer <david.oberhollenzer@tele2.at>2018-09-21 12:41:42 +0200
committerDavid Oberhollenzer <david.oberhollenzer@tele2.at>2018-09-21 12:41:42 +0200
commit66dde441bc7ae0462363fd78250f297f9289ce20 (patch)
treeaea2e800ba767fecbd3995ecee0d5c23b19e18d1 /scripts/setntpdate.sh
parent33aa4cedff0f8d0a09f80460568c296da8d16d26 (diff)
Add helper script to update the time from NTP
Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>
Diffstat (limited to 'scripts/setntpdate.sh')
-rwxr-xr-xscripts/setntpdate.sh67
1 files changed, 67 insertions, 0 deletions
diff --git a/scripts/setntpdate.sh b/scripts/setntpdate.sh
new file mode 100755
index 0000000..c0ed1b4
--- /dev/null
+++ b/scripts/setntpdate.sh
@@ -0,0 +1,67 @@
+#!/bin/sh
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# Copyright (C) 2018 - David Oberhollenzer
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <https://www.gnu.org/licenses/>.
+#
+
+resolve() {
+ local domain="$1"
+ local server="$2"
+
+ if [ -x "$(command -v dig)" ]; then
+ if [ -z "$server" ]; then
+ dig +short "$domain"
+ else
+ dig +short "@$server" "$domain"
+ fi
+ return $?
+ fi
+
+ if [ -x "$(command -v drill)" ]; then
+ if [ -z "$server" ]; then
+ drill "$domain" | grep "^${domain}." | cut -d$'\t' -f5
+ else
+ drill "@$server" "$domain" | grep "^${domain}." |\
+ cut -d$'\t' -f5
+ fi
+ return $?
+ fi
+ exit 1
+}
+
+try_update() {
+ while read ip; do
+ if ntpdate -bu "$ip"; then
+ return 0
+ fi
+ done
+
+ return 1
+}
+
+pool="pool.ntp.org"
+dns="1.1.1.1"
+
+# try default DNS server first
+resolve "$pool" "" | try_update
+[ $? -eq 0 ] && exit 0
+
+# try fallback public dns server
+ping -q -c 1 "$dns" || exit 1
+
+resolve "$pool" "$dns" | try_update
+exit $?