How can I check if mysql is installed using a bash script?

Question

I need to check if mysql is installed from within a bash script. What would be an efficient way of doing that? I thought I could do this:

if [ ! -f `which mysql` ] ; then
    echo "foo" 
fi

But I think I might be confused about something. What would be a better solution? It should be portable and work on both Ubuntu and OSX.

Solution 1

type mysql >/dev/null 2>&1 && echo "MySQL present." || echo "MySQL not present."

Solution 2

If you exclusively use your Ubuntu package manager for MySQL installation, then you can just use the dpkg front-end to dpkg-query to find out whether the package is installed.

# Look up package with dpkg-query.
if dpkg --list mysql-client | egrep -q ^ii; then
    :
fi

This is fast and reliable, but obviously only works when you use your Ubuntu system packages.

Comments

[Admin]

What exactly confuses you about the code you posted? What did you expect it to do, and what does it do instead?

[Admin]

which only returns regular files anyway. This test will always be false.

[Admin]

@kopischke I expected which mysql to give back the path to mysql that then is checked if it's a file or not. But it seems to just not work.

[Admin]

This will also potentially break in any shell where [ is an external command, as if which does not return anything, -f will be missing an argument.

[Admin]

Also, using which will fail if mysql is an alias.

[Bram]

What is the problem with searching only in $PATH? If it is installed in a non-standard location you need to know that location to run it anyway. And if you know the non-standard location it probably doesn't make much sense to run a script that checks if it is installed or not.

[George M]

@Bram Being installed does not implicitly mean it's going to be in a standard location. What if, as root, I want to know how many mysqld binaries users have compiled and installed on the system? It could be in /opt (not usually considered standard), could be under some user /home directory, could be in a subdirectory under /usr/local. There could also be multiple versions of mysqld installed. Assuming the binary is going to be in $PATH or it's irrelevant is not, in my opinion, a good view to have.

[clerksx]

@Bram - I have absolutely no idea. I'm just providing an alternative for uther's answer.

[Gilles 'SO- stop being evil']

I do not recommend running find over the entire filesystem. It's rude. You may be traversing external drives, network mounts, … If mysql isn't in the path, it might as well not be installed. There might be a non-working installation of mysql that's not in the path on purpose.