Running a bash shell using a password with a cron job

I have a bash shell to back up a database that requires a password to open it. I want to run on a cron job, but how do I make it run automatically without filling in the database password?

ubuntu server version : 20.04.3 Mysql version : 8.0.26

The command i tried : mysqldump -u root -p "dbname" > backupname.sql when I press enter, the system asks for password. when i remove -p, error occurs.

In order to use mysqldump with the root MySQL account, you will need to prefix your command with sudo:

sudo mysqldump database_name > backup.sql

If you would like to run this via a cron job, then you can do something like this:

0 3 * * * mysqldump database_name > /path/to/backups/backup.sql

As a bonus, if you would like to compress that backup and have the file name contain the date, you can do something like this:

0 3 * * * mysqldump database_name | gzip > /path/to/backups/backup_$(date +\%Y-\%m-\%d).gz

Be sure to include the necessary --routines and --triggers options in your mysqldump command if your database contains either stored procedures or triggers.

Basically, you can either add the following to you my.cnffile

[mysqldump]
user=mysqluser
password=secret

Alternatively, you can export the following before calling mysqldump

MYSQL_PWD=yourverysecretpassword

Using the -p parameter as you tried is strongly discouraged for security reasons.

More info and extended solutions on https://stackoverflow.com/questions/9293042/how-to-perform-a-mysqldump-without-a-password-prompt