I am trying to backup my mysql database using linux crontab like below command,
$crontab -e
15 * * * * /usr/bin/mysqldump -u XXX-pXXX demobackupDB > /home/user/DBbackup/$(date +%F)_backup.sql
But i dont find that .sql file in the specific folder after every 15 mins.
How to find what is error and fix it?
You have wrong crontab. What you specified is "run task at 15 minutes after each hour".
You need this crontab to run task every 15 minutes:
*/15 * * * * /usr/bin/mysqldump -u XXX-pXXX demobackupDB > /home/user/DBbackup/$(date +%F)_backup.sql
If your job is still not running there could be many reasons of this.
You can start debugging with the simple test like this:
* * * * * echo hi >> /home/user/test
(You should see a new line "hi" appended to /home/user/test file once a minute)
If this is not the case see probable reasons for ubuntu here: https://askubuntu.com/q/23009.
Also see cron log: https://askubuntu.com/q/56683/103599
mysqldump command manually in shell? (without crontab)/usr/bin/mysqldump -u XXX-pXXX demobackupDB > /home/user/DBbackup/$(date +%F)_backup.sql) directly in bash to see if there is any problem with it and debug it without involving cron.You can create a file with your statement and make it executable
echo '/usr/bin/mysqldump -u XXX-pXXX demobackupDB > /home/user/DBbackup/$(date +%F)_backup.sql' > backupjob
Make them executable
chmod +x backupjob
And run it
sudo ./backupjob
If everything is fine, the mysql-backup-file should be created. If not, go on with debugging your statement else change your cronjob entry:
cronjob -e
# My MySQL-Backup-Job
*/15 * * * * /yourpath/backup
...
Important: The Crontab-Table must end with an empty line!
For further Informations: Ubuntu - Cron
/var/log/apache2/error.logfile