I just got a CentOS VPS and was reviewing the passwd file and saw this:mysql:x:498:499:MySQL server:/var/lib/mysql:/bin/bashIs bash necessary for mysql?
/etc/passwd sql with bash access
centos;security;users;mysql
The shell may need to be set in some circumstances, for example if you want to initiate jobs remotely over SSH as the mysql user, or through sudo. These aren't common needs. You don't need to have a shell set for cron jobs, /bin/false will do fine.Giving the mysql user a shell isn't a security hole on its own. The reason it's frowned upon is that compounded with a misconfiguration of some login service, it might allow someone to obtain a shell as mysql. Putting a program that does nothing avoids this  even if an attacker manages to log in as mysql that won't do them any good. It's common to use /bin/false or /usr/sbin/nologin, but /bin/true or any other no-op program would be fine.