Where is cron job file is located
File located in the every user Home directory file name “.crontab” or /etc/crontab
crontab it is refers to the cron table
SYNTAX
Minutes:Hours:Day:Month:Day of the Week
[0-59]:[0-23]:[0-31]:[0-12]:[0-7]
15 * * * 2,4,6 myscript
it will run the script Tuesday Thursday and Saturday
Crontab Different Option
crontab –e Edit the cron tab file for the current user
crontab -l List the cron job
crontab -r remvoe the cron job
Crontab Example
1 0 * * * echo -n "" > /var/log/dmesg
These command run every day and clear the log file
How To Backup The Crontab File
crontab -l >backup_cronjob_10-2-2010
crontab -l > /path/to/your/backup/file
Ever day Backup
Run Ten Minutes after midnight, every day
:10 0 * * * /var/backup.sh
Monthly Backup
Run at 5:30pm on the second of every month
:30 17 2 * * /var/monthbackup.sh
Weekly Backup
Run at 11pm on weekdays
: 0 23 * * 1-5 /var/weekdays.sh
Linux at command
At schedule the task at only once
[root@bash ~]#at 8:20pm
at> init 6
at>
job 2 at 2010-08-05 20:20
Can't open /var/run/atd.pid to signal atd. No atd running?
Run the at command At specified Time and Day
[root@bash ~]#at 10am sunday
at> echo "welcome"
At Command Specified Date and Time
[root@bash ~]#at 6am Aug 20
at> echo "$Joshi Mariiage wedding Day"
Atq it will display list of the queue in the at command
[root@bash ~]#atq
1 2010-08-05 20:00 a root
3 2010-08-08 10:00 a root
2 2010-08-05 20:20 a root
Where confab file is is located
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