??????????????????
????************************************************************************************
????cron?????linux?μ?????й????????????????????????????????????????Cron ??Linux?????÷???????????????????????????μ???????????????????
????/sbin/service crond start //???????
????/sbin/service crond stop //??????
????/sbin/service crond restart //???????
????/sbin/service crond reload //????????????
???????????????????????????????????????
??????/etc/rc.d/rc.local?????????β?????
????/sbin/service crond start
????????Cron?????????????????????????????????????????Cron???????????????????????
????1.?????crontab?????
????cron??????crontab???????趨cron?????????????????????Щ???????????
????crontab -u //?趨????????cron???????root???????????????????????????
????crontab -l //?г???????cron????????????
????crontab -r //???????????cron????
????crontab -e //??????????cron????
?????????root???????cron?????crontab -u root -l
?????????磬root?????fred??cron?????crontab -u fred -r
???????cron??????????????????Щ??????????????crontab -u root -e
????????vi???????????????????????????????*/1 * * * * ls >> /tmp/ls.txt
??????????????????????????趨????????????????е???????????е???????????????Щ????д???????????棬??????????????????????????????????????д???????????·?????????趨??????????????????????*??????????????????????Χ????????￡?
???????? (0-59)
????С?(0-23)
????????(1-31)
?????·?(1-12)
????????(0-6) //0??????????
??????????????м???????????????"*"??"/"??"-"??"??"??*???????е?????Χ????????"/"????????????"*/5"????5????λ??"-"?????????????????????"??"????????????????????????????????????
???????????6??
????-----------------
????0 6 * * * echo "Good morning." >> /tmp/test.txt //?????echo???????????????κ?????????cron???κ??????email??root?????????
?????????С?
????-----------------
????0 */2 * * * echo "Have a break now." >> /tmp/test.txt
????????11??????8??????????С?????????
????-----------------
????0 23-7/28 * * * echo "Have a good dream????" >> /tmp/test.txt
????????μ?4???????????????????????????11??
????-----------------
????0 11 4 * 1-3 command line
????1??1??????4??
????-----------------
????0 4 1 1 * command line
??????α???????????cron???ú?cron?????/var/spool/cron????????????????????????????????cron?????????????????У????????????????????????????crontab -e ??????cron????????????????????????????????????????????????????????????????cron????
????2.??/etc/crontab ???????cron
????cron??????????????????/var/spool/cron??????????????????????/etc/crontab??????????????????????????cron???????Щ???顣??crontab??????????????????????/etc/crontab?????????????????????????????
????SHELL=/bin/bash
????PATH=/sbin:/bin:/usr/sbin:/usr/bin
????MAILTO=root //?????????????????????????????????????????????
????HOME=/      //????????е?·?????????????
????# run-parts
????01 * * * * root run-parts /etc/cron.hourly //?С????/etc/cron.hourly?????
????02 4 * * * root run-parts /etc/cron.daily //??????/etc/cron.daily?????
????22 4 * * 0 root run-parts /etc/cron.weekly //????????/etc/cron.weekly?????
????42 4 1 * * root run-parts /etc/cron.monthly //???????/etc/cron.monthly?????
??????????"run-parts"???????????????????????????????????д????е???????????????????????????