Bash check if MySQL is installed

DennisD

I'm writing a simple bash script and I need to check whether MySQL is installed or not.

I tried "if [[ -n $(which mysql-server) ]]; then" but that doesn't seem to work. Anyone an idea?

ricardo

mysqld

CharlesA

+1 to @ricardo

It would probably be a good idea to use the full path to mysqld too.

socials

I've used

type mysql &> /dev/null && echo "installed" || echo "not installed"

DennisD

@CharlesA said:
+1 to ricardo

It would probably be a good idea to use the full path to mysqld too.

Can you please post a code snippet? Don't get it to work.

Silvenga

which is not recommended because of OS dependent exit status (it may not always work). type is prefered in Bash.

For example:

if type mysql >/dev/null 2>&1; then
    echo "Dumping databases..." >>$LOGLOC
    USER="root"
    # ....
else
    echo "Skipping Database dump." >>$LOGLOC
fi

CharlesA

@DennisD said:

It should exist here, at least on Debian: /usr/sbin/mysqld

Silvenga has a good idea too.

DennisD

I'm now trying to check the MySQL connection, it works fine, but how do I stop the command from outputting "MySQL root password: ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)" when a wrong password is entered.

http://pastebin.com/Ggu1GgSh

DennisD

Got it, thanks for helping everyone!

hostnoob

@DennisD said:
I'm now trying to check the MySQL connection, it works fine, but how do I stop the command from outputting "MySQL root password: ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)" when a wrong password is entered.

http://pastebin.com/Ggu1GgSh

I just use fsockopen to check port 3306 (or custom MySQL port if used) not sure what the Bash alternative is

alessio

Can you explain what you exactly want to achieve? How do you define installed? Relying on the path, like some mentioned, might help in many cases but not in all. There could be a MySQL instance sitting somewhere quietly in a directory and you'd never find it via the path.

hostnoob said: I just use fsockopen to check port 3306 (or custom MySQL port if used)

This works if you are in a familiar environment. It wouldnt work as generic way though. Something else could be listening on 3306, it could be on some random port or on no port at all.

Silvenga

hostnoob said: not sure what the Bash alternative is

Maybe check if the Unix socket file exists?

alessio said: Something else could be listening on 3306

Although this is probably overkill, we could check what process is using that port using something likenetstat.

Profforg

Silvenga said: Although this is probably overkill, we could check what process is using that port using something likenetstat.

I think on high-load, netstat will be worser than try to connect to port.

alessio

Silvenga said: Although this is probably overkill, we could check what process is using that port using something likenetstat.

Checking for the port would be still a problem if it uses the domain socket. However using netstat might be actually the most promising approach, given the script executes under root, nobody had the funny idea of renaming the executable and you check for the listeners and domain sockets.

Silvenga

Profforg said: I think on high-load, netstat will be worser than try to connect to port.

Why? Netstat is basically a data parser and it would only be used to ensure that the socket is owned by a mysql binary.

hostnoob

@alessio said:
Can you explain what you exactly want to achieve? How do you define installed? Relying on the path, like some mentioned, might help in many cases but not in all. There could be a MySQL instance sitting somewhere quietly in a directory and you'd never find it via the path.

This works if you are in a familiar environment. It wouldnt work as generic way though. Something else could be listening on 3306, it could be on some random port or on no port at all.

It's part of a script that has a config file for the user to set the services to be monitored and which ports they're running on

alessio

@hostnoob said:
It's part of a script that has a config file for the user to set the services to be monitored and which ports they're running on

So an automatic pre-selection of services which the user can change and modify? In this case it probably doesnt need to be foolproof and they easiest way might be the which/type path.