251 lines
6.4 KiB
Bash
251 lines
6.4 KiB
Bash
#!/bin/bash
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# This script configures running chronyd to use NTP servers obtained from
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# DHCP and _ntp._udp DNS SRV records. Files with servers from DHCP are managed
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# externally (e.g. by a dhclient script). Files with servers from DNS SRV
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# records are updated here using the dig utility. The script can also list
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# and set static sources in the chronyd configuration file.
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chronyc=/usr/bin/chronyc
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chrony_conf=/etc/chrony.conf
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chrony_service=chronyd.service
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helper_dir=/var/run/chrony-helper
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added_servers_file=$helper_dir/added_servers
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network_sysconfig_file=/etc/sysconfig/network
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dhclient_servers_files=/var/lib/dhclient/chrony.servers.*
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dnssrv_servers_files=$helper_dir/dnssrv@*
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dnssrv_timer_prefix=chrony-dnssrv@
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chrony_command() {
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$chronyc -a -n -m "$1"
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}
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is_running() {
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chrony_command "tracking" &> /dev/null
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}
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is_update_needed() {
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for file in $dhclient_servers_files $dnssrv_servers_files \
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$added_servers_file; do
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[ -e "$file" ] && return 0
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done
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return 1
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}
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update_daemon() {
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local all_servers_with_args all_servers added_servers
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if ! is_running; then
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rm -f $added_servers_file
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return 0
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fi
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all_servers_with_args=$(
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cat $dhclient_servers_files $dnssrv_servers_files 2> /dev/null)
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all_servers=$(
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echo "$all_servers_with_args" |
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while read server serverargs; do
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echo "$server"
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done | sort -u)
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added_servers=$( (
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cat $added_servers_file 2> /dev/null
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echo "$all_servers_with_args" |
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while read server serverargs; do
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[ -z "$server" ] && continue
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chrony_command "add server $server $serverargs" &> /dev/null &&
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echo "$server"
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done) | sort -u)
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comm -23 <(echo -n "$added_servers") <(echo -n "$all_servers") |
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while read server; do
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chrony_command "delete $server" &> /dev/null
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done
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added_servers=$(comm -12 <(echo -n "$added_servers") <(echo -n "$all_servers"))
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[ -n "$added_servers" ] && echo "$added_servers" > $added_servers_file ||
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rm -f $added_servers_file
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}
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get_dnssrv_servers() {
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local name=$1
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if ! command -v dig &> /dev/null; then
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echo "Missing dig (DNS lookup utility)" >&2
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return 1
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fi
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(
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. $network_sysconfig_file &> /dev/null
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output=$(dig "$name" srv +short +ndots=2 +search 2> /dev/null)
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[ $? -ne 0 ] && return 0
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echo "$output" | while read prio weight port target; do
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server=${target%.}
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[ -z "$server" ] && continue
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echo "$server port $port ${NTPSERVERARGS:-iburst}"
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done
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)
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}
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check_dnssrv_name() {
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local name=$1
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if [ -z "$name" ]; then
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echo "No DNS SRV name specified" >&2
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return 1
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fi
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if [ "${name:0:9}" != _ntp._udp ]; then
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echo "DNS SRV name $name doesn't start with _ntp._udp" >&2
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return 1
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fi
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}
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update_dnssrv_servers() {
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local name=$1
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local srv_file=$helper_dir/dnssrv@$name servers
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check_dnssrv_name "$name" || return 1
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servers=$(get_dnssrv_servers "$name")
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[ -n "$servers" ] && echo "$servers" > "$srv_file" || rm -f "$srv_file"
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}
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set_dnssrv_timer() {
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local state=$1 name=$2
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local srv_file=$helper_dir/dnssrv@$name servers
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local timer=$dnssrv_timer_prefix$(systemd-escape "$name").timer
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check_dnssrv_name "$name" || return 1
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if [ "$state" = enable ]; then
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systemctl enable "$timer"
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systemctl start "$timer"
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elif [ "$state" = disable ]; then
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systemctl stop "$timer"
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systemctl disable "$timer"
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rm -f "$srv_file"
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fi
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}
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list_dnssrv_timers() {
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systemctl --all --full -t timer list-units | grep "^$dnssrv_timer_prefix" | \
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sed "s|^$dnssrv_timer_prefix\(.*\)\.timer.*|\1|" |
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while read -r name; do
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systemd-escape --unescape "$name"
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done
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}
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prepare_helper_dir() {
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mkdir -p $helper_dir
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exec 100> $helper_dir/lock
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if ! flock -w 20 100; then
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echo "Failed to lock $helper_dir" >&2
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return 1
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fi
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}
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is_source_line() {
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local pattern="^[ \t]*(server|pool|peer|refclock)[ \t]+[^ \t]+"
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[[ "$1" =~ $pattern ]]
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}
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list_static_sources() {
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while read line; do
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is_source_line "$line" && echo "$line" || :
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done < $chrony_conf
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}
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set_static_sources() {
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local new_config tmp_conf
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new_config=$(
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sources=$(
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while read line; do
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is_source_line "$line" && echo "$line"
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done)
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while read line; do
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if ! is_source_line "$line"; then
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echo "$line"
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continue
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fi
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tmp_sources=$(
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local removed=0
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echo "$sources" | while read line2; do
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[ "$removed" -ne 0 -o "$line" != "$line2" ] && \
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echo "$line2" || removed=1
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done)
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[ "$sources" == "$tmp_sources" ] && continue
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sources=$tmp_sources
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echo "$line"
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done < $chrony_conf
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echo "$sources"
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)
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tmp_conf=${chrony_conf}.tmp
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cp -a $chrony_conf $tmp_conf &&
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echo "$new_config" > $tmp_conf &&
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mv $tmp_conf $chrony_conf || return 1
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systemctl try-restart $chrony_service
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}
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print_help() {
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echo "Usage: $0 COMMAND"
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echo
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echo "Commands:"
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echo " update-daemon"
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echo " update-dnssrv-servers NAME"
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echo " enable-dnssrv NAME"
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echo " disable-dnssrv NAME"
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echo " list-dnssrv"
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echo " list-static-sources"
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echo " set-static-sources < sources.list"
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echo " is-running"
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echo " command CHRONYC-COMMAND"
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}
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case "$1" in
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update-daemon|add-dhclient-servers|remove-dhclient-servers)
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is_update_needed || exit 0
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prepare_helper_dir && update_daemon
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;;
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update-dnssrv-servers)
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prepare_helper_dir && update_dnssrv_servers "$2" && update_daemon
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;;
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enable-dnssrv)
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set_dnssrv_timer enable "$2"
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;;
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disable-dnssrv)
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set_dnssrv_timer disable "$2" && prepare_helper_dir && update_daemon
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;;
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list-dnssrv)
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list_dnssrv_timers
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;;
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list-static-sources)
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list_static_sources
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;;
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set-static-sources)
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set_static_sources
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;;
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is-running)
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is_running
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;;
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command|forced-command)
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chrony_command "$2"
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;;
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*)
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print_help
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exit 2
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esac
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exit $? |