????????? at ????????????????ε???????????е?????????????linux???????? cron (crond) ?????????????????Linux ??????????з????????????????????????????????????????? ????????????????????ü??????????? Linux ?????????????????????????? :crontab ???
???????crond???
????crond??linux???????????????????????????????Щ??????????????????windows?μ???????????????????????????????????????????????????crond?????crond??????????????????????е?????????????е????????????и?????
????Linux?μ???????????????????????????????????
???????????????????????????е??????????д????????????????????????/etc?????????crontab?????????????????????????????
????/etc/crontab??????????漸?У?
????[root@localhost ~]# cat /etc/crontab
????SHELL=/bin/bash
????PATH=/sbin:/bin:/usr/sbin:/usr/bin
????MAILTO=””HOME=/
????# run-parts
????51 * * * * root run-parts /etc/cron.hourly
????24 7 * * * root run-parts /etc/cron.daily
????22 4 * * 0 root run-parts /etc/cron.weekly
????42 4 1 * * root run-parts /etc/cron.monthly
????[root@localhost ~]#
???????????????????crond???????е???????????????SHELL??????????????????shell????????bash???????PATH???????????????????·??????????MAILTO?????????crond?????????????????????????????root????????MAILTO???????????????????????????????????????????е?HOME???????????????????????????????????????????б??????彫?????С?????????????????????
?????????????????????????е??????????????????????????????????????????? crontab ?????????????????????????????????crontab ????????????? /var/spool/cron???С???????????????????
?????????????????
?????????
????/etc/cron.deny
?????????
???????????????????????????crontab????
?????????
????/etc/cron.allow
?????????
?????????????????????????crontab????
?????????
????/var/spool/cron/
?????????
???????????crontab??????????????????????
????crontab???????壺
???????????????crontab????У????ж??????????????е??????δ????????????????????????????Σ???????????趨?Σ????????????е?????Σ???????￡?
????minute   hour   day   month   week   command
???????У?
????minute?? ???????????????0??59?????κ???????
????hour?????С??????????0??23?????κ???????
????day?????????????????1??31?????κ???????
????month??????·?????????1??12?????κ???????
????week???????????????????0??7?????κ????????????0??7???????????
????command?????е?????????????????????????????д?????????

?????????????????У???????????????????????
????????*???????????п???????????month????????????????????????????ε????????????????и??????????
????????????????????????????????????б??Χ?????磬“1??2??5??7??8??9”
?????и??-???????????????????и????????????Χ??????“2-6”???“2??3??4??5??6”
??????б???/????????????б???????????????????“0-23/2”??????С??????Ρ?????б????????????????????*/10?????????minute??Σ???????????????Ρ?
????????crond????
???????crontab??
????yum install crontabs
????????????????
????/sbin/service crond start //???????
????/sbin/service crond stop //??????
????/sbin/service crond restart //???????
????/sbin/service crond reload //????????????
??????crontab????????
????service crond status
??????????crontab????
????service crond start
??????crontab??????????????????????????????
????ntsysv
??????????????????
????chkconfig –level 35 crond on
????????crontab???????
????1??????????
????crontab [-u user] file
????crontab [-u user] [ -e | -l | -r ]
????2?????????
???????crontab ???????????????????????????????????? shell script????????????λ??????????С??????????????????????????????????????????????????????????????????
????3???????????
????-u user???????趨????????crontab???????磬“-u ixdba”????趨ixdba?????crontab??????????????root????????С?
????file??file?????????????????????file???crontab???????б??????????crontab?????????????????????????????crontab?????????????????????????????????????????crontab??
????-e????????????crontab???????????????????????????????????crontab?????
????-l?????????????crontab????????????????????????????????????crontab????????
????-r????/var/spool/cron???????????????crontab??????????????????????????????????crontab?????
????-i????????????crontab??????????????
????4?????÷?????
????1). ????????μ?crontab???
???????????cron?????????crontab????????????????????????????????????EDITOR??cron??????????????????????????crontab?????9 9 %??UNIX??LINUX????????vi??????????????????????$ HOME???μ?. profile??????????м?????????У?
????EDITOR=vi; export EDITOR
????????沢???????????????????<user> cron???????????<user>????????????磬 davecron?????????м??????μ??????
????# (put your own initials here)echo the date to the console every
????# 15minutes between 6pm and 6am
????0??15??30??45 18-06 * * * /bin/echo ‘date’ > /dev/console
???????沢???????????5???????????
????????????????У????????1 5???????????????ε???????????????????????????????????????????????????????????????Щ???У???tty1??????????????????????????????????????????????????????????????crontab??????????????′???????????cron??????????
????$ crontab davecron
???????????????????cron????????????1 5??????????Ρ?
?????????′????????????????????????/var/spool/cron???У?????????????(??dave)??
????2). ?г?crontab???
????????г?crontab????????????
????$ crontab -l
????0??15??30??45??18-06 * * * /bin/echo `date` > dev/tty1
??????????????????????????????????????????$ H O M E???ж?crontab???????????
????$ crontab -l > $HOME/mycron
???????????????С???????crontab??????????????????????????????????
????3). ??crontab???
????????????????????crontab????е????????E D I TO R???????????????v i???????????v i????crontab?????????????????
????$ crontab -e
?????????????v i???????κ???????????crontab???????????????????Щ???????????μ????????????????????? c r o n???????б???????????顣??????е???????????????????Χ??????????????
???????????crontab??????????????μ?????????磬??????????????
????# DT:delete core files??at 3.30am on 1??7??14??21??26??26 days of each month
????30 3 1??7??14??21??26 * * /bin/find -name “core’ -exec rm {} ;
??????????沢?????????crontab???????????????????????????????????????????????????????????????????????λ??????????
???????????????????潲????crontab -l?????г?????????????
????$ crontab -l
????# (crondave installed on Tue May 4 13:07:43 1999)
????# DT:ech the date to the console every 30 minites
????0??15??30??45 18-06 * * * /bin/echo `date` > /dev/tty1
????# DT:delete core files??at 3.30am on 1??7??14??21??26??26 days of each month
????30 3 1??7??14??21??26 * * /bin/find -name “core’ -exec rm {} ;
????4). ???crontab???
????????crontab????????????
????$ crontab -r
????5). ????????crontab???
?????????С???????crontab??????????????????$ H O M E????????????????????????俽????/var/spool/cron/<username>??????<username>?????????????????????????????????????????
????$ crontab <filename>
???????У?<filename>??????$ H O M E???и????????????
??????????????????$ H O M E???б?????????????????????й??????????????????????crontab????????r???????e???????????????????Щ????????鯔?????crontab????????????????????????????????????μ??????
??????Щcrontab???????Щ?????????????crontab??????????С????????????κ????crontab??????????????????????????????????????????delete????????????<Ctrl-D>???????????crontab?????