????1.????
????????linux?????????з???????
????2.???
????(1)linux??ntpdate??tcp??udp??http??У?????п????????????????????汾??????????????????????????????Щ??????????????linux???????????????У????д???shell?????????????????????е?????????????????裬д??shell???
????????????????20????????????3?????
??????:???????д??????????test.sh????????:

 

echo $(date +"%H:%M" ) > /root/home/timeSyn/test.txt
time1=$(date -d '3 minutes' +"%H:%M" )
echo $time1 > /root/home/timeSyn/test1.txt
date -s "$time1"
exit

??????????????????? crontab -e???????shell????????????????:

 

*/20 * * * *  /root/test/test.sh

??????????????????′????????????????

 

/sbin/service crond restart
ok!