busybox/examples/var_service/ntpd/run

#!/bin/bash
# (using bashism (arrays) in dhcp config)

#exec >/dev/null
exec 2>&1
exec </dev/null

user=root
pool="us.pool.ntp.org" # replace "us" with your country code

service="${PWD##*/}"
rundir="/var/run/service/$service"
default_p_opt="-p 0.$pool -p 1.$pool -p 2.$pool -p 3.$pool"


# Make sure rundir/ exists
mkdir -p "$rundir" 2>/dev/null
chown -R "$user:" "$rundir"
chmod -R a=rX "$rundir"
rm -rf rundir 2>/dev/null
ln -s "$rundir" rundir


echo "* Checking network"
test -f /var/run/service/fw/up || exec sleep 7
sleep 5  # to let it settle

# Grab config from dhcp
cfg=-1
for f in rundir/*.ntpconf; do
        test -f "$f" || continue
        . "$f"
done

# Select peers
p_opt=""
cfg=0
while test x"${ntpip[$cfg]}" != x""; do
        p_opt="$p_opt -p ${ntpip[$cfg]}"
        let cfg=cfg+1
done
test x"$p_opt" == x"" && p_opt="$default_p_opt"

if test x"$p_opt" == x""; then
	echo "* No NTP peers configured, stopping"
	sv o .
	exec sleep 1
fi


# Let others know that we are up
date '+%Y-%m-%d %H:%M:%S %Z' >rundir/up

# Go go go
echo "* Starting ntpd[$$]"
exec \
env - PATH="$PATH" \
softlimit \
setuidgid "$user" \
ntpd -ddnNl -S ./ntp.script $p_opt