????????????????????????????????????Linux??????н???????á?Linux?μ??????????????crontab????м???????????У??????Windows????????Щ(????????ν?????)?????????????????????????ù????????????????????/var/spool/cron??????????濴????????÷???
????????????/etc/crontab?????
????$ cat /etc/crontab
????SHELL=/bin/bash
????PATH=/sbin:/bin:/usr/sbin:/usr/bin
????MAILTO=root
????HOME=/
????# run-parts
????01 * * * * root run-parts /etc/cron.hourly
????02 4 * * * root run-parts /etc/cron.daily
????22 4 * * 0 root run-parts /etc/cron.weekly
????42 4 1 * * root run-parts /etc/cron.monthly
????????????й?????cron???????е??????????SHELL????????????????SHELL????(???????bash shell)??PATH??????????????????·????Cron??????????????????????MAILTO???????????????????MAILTO????????????????(MAILTO="")?????????????????????????????HOME???????????????????
???????/etc/crontab?????????????????????:
????minute hour day month dayofweek command
????minute - ??0??59??????
????hour - ??0??23??????
????day - ??1??31?????? (??????????·????Ч????)
????month - ??1??12?????? (????Jan??Feb??д???·?)
????dayofweek - ??0??7????????0??7???????????? (????Sun??Mon??д?????)
????command - ?????е?????(????as ls /proc >> /tmp/proc?? ????????????????)
????root?????root????????????
????run-parts????????????????????У????е??????????μ????н??
???????????????????(*)??????п???????????*?????month??????????(???????????????????)?????
????????????????(-)????????У?????1-4?????????1??2??3??4
????????????????????磺3??4??6??8?????????????????
????????“/”??????????á?“/<interger>”????????????0-59/2????????????????Ρ????????????????????*/3??????????????·????????????
??????“#”??????????У???????С?
??????????cron?????????????????С??????????????У?????????/etc/cron.d??????????μ?????????????/etc/crontab???????????????
????# record the memory usage of the system every monday
????# at 3:30AM in the file /tmp/meminfo
????30 3 * * mon cat /proc/meminfo >> /tmp/meminfo
????# run custom scr??pt the first day of every month at 4:10AM
????10 4 1 * * /root/scr??pts/backup.sh
????????root?????????????????crontab???ü??????????????????crontab?洢????/var/spool/cron?￡????????????????????С?????????????????crontab??????????????????????crontab -e???????????VISUAL????EDITOR??????????????crontab???????????/etc/crontab??????????????￡?
????0 3 * * * /home/dbbackup/db1backup.sh backup
????0 4 * * * /home/dbbackup/db2backup.sh backup
??????????3?????/home/dbbackup/db1backup.sh backup??4?????/home/dbbackup/db2backup.sh backup??????????????????ο?????
????*/5 * * * * /home/dbbackup/db2backup.sh backup
???????????crontab???????????????????????????/var/spool/cron/username????????????????????????
????cron???????????????/etc/crontab??/etc/cron.d/??/var/spool/cron????μ????????????仯??????????洢???С????????crontab????????????????????????????????????????????crontab -e???????????????/etc/init.d/crond restart????????crond???????????????????????????????????????????????????????????????/etc/crontab????е?run-parts???????????????????/etc/crontab??????????????????У??????????run-parts?????????????????С?