Check if mysql database exists, perform action based on result

Question

Is it possible from within a bash script to check if a mysql database exists. Depending on the result then perform another action or terminate the script?

Answer 1

I give +1 to answer by @chown, but here's another alternative: If the bash script is running locally with the MySQL instance, and you know the path to the datadir, you can test:

if [ -d /var/lib/mysql/databasename ] ; then      # Do Stuff ... fi 

This also assumes your shell user running the script has filesystem-level privileges to read the contents of the MySQL datadir. This is often the case, but it is not certain.

Answer 2

Example script (Thanks to Bill Karwin for the --user and --password comment!):

#!/bin/bash ## --user=XXXXXX --password=XXXXXX *may* not be necessary if run as root or you have unsecured DBs but ##   using them makes this script a lot more portable.  Thanks @billkarwin RESULT=`mysqlshow --user=XXXXXX --password=XXXXXX myDatabase| grep -v Wildcard | grep -o myDatabase` if [ "$RESULT" == "myDatabase" ]; then     echo YES fi 

These are what the commands look like when run at a prompt:

[root@host ~]# mysqlshow myDatabase Wildcard: myDatabase +------------------+ |    Databases     | +------------------+ | myDatabase       | +------------------+ 

If no DB exists, the output will look like this:

[root@host ~]# mysqlshow myDatabase Wildcard: myDatabase +-----------+ | Databases | +-----------+ +-----------+ 

Then, parse the output and do what you need to based on if it exists or not!