gem install mysql

Let's pretend you have installed mysql with yum on your fedora box, and you want to install the mysql gem so you can take advantage of it's c binding goodness.

With giddy excitement you bash away at the keyboard and run the following command:

gem install mysql

But wait, what's this? An error the likes of which would consume small children given the chance:

checking for mysql_query() in -lmysqlclient... no

checking for main() in -lm... yes

checking for mysql_query() in -lmysqlclient... no

checking for main() in -lz... yes

checking for mysql_query() in -lmysqlclient... no

checking for main() in -lsocket... no

checking for mysql_query() in -lmysqlclient... no

checking for main() in -lnsl... yes

checking for mysql_query() in -lmysqlclient... no

*** extconf.rb failed ***

Could not create Makefile due to some reason, probably lack of

necessary libraries and/or headers. Check the mkmf.log file for more

details. You may need configuration options.

Fear not! For it probably doesn't know how to find you mysql_config file. Try something along the following lines:

sudo gem install mysql -- --with-mysql-config=/usr/lib/mysql/mysql_config

The location of mysql_config may vary depending on your system installation.

SELinux: PERMISSION DENIED!!!!

Doing a Rails app installation on Fedora Core 8, I kept getting "Permission Denied" errors.

I checked file permission, wept, begged and even went on a holy walk to try massage this problem into oblivion.

As it turns out, there's this dear little linux feature that came free of charge with my fedora installation: SELinux (Pronounced "seeeed-OF-eeviel"). This gem of a feature enforced security policies, which need to take your rails app's location into account, which you can do as follows:

chcon -R -t httpd_sys_content_t /path/to/your/app