/etc/network/if-up.d/ntpdate is in ntpsec-ntpdate 1.1.0+dfsg1-1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 | #!/bin/sh
set -e
PATH=/sbin:/bin:/usr/sbin:/usr/bin
# This is a heuristic: The idea is that if a static interface is brought
# up, that is a major event, and we can put in some extra effort to fix
# the system time. Feel free to change this, especially if you regularly
# bring up new network interfaces.
if [ "$METHOD" = static ]; then
OPTS="-b"
fi
if [ "$METHOD" = loopback ] || [ "$METHOD" = none ]; then
exit 0
fi
# Check whether ntpdate was removed but not purged; it's useless to wait for
# it in that case.
if [ ! -x /usr/sbin/ntpdate-debian ] && [ -d /usr/sbin ]; then
exit 0
fi
(
# This is for the case that /usr will be mounted later.
if [ -r /lib/udev/hotplug.functions ]; then
. /lib/udev/hotplug.functions
wait_for_file /usr/sbin/ntpdate-debian
fi
if [ -e /usr/sbin/openntpd ]; then
service='openntpd'
else
service='ntp'
fi
invoke-rc.d --quiet $service stop >/dev/null 2>&1 || true
# Avoid running more than one at a time
flock -n /run/lock/ntpdate /usr/sbin/ntpdate-debian -s $OPTS 2>/dev/null || :
invoke-rc.d --quiet $service start >/dev/null 2>&1 || true
) &
|