Props to David Latham: Apache and SELinux

So, I was working on a CentOS 6.4 box to set up an SVN server. Early in the process, I decided I would try (for the first time) to successfully live with SELinux and its requirements, hoops and other arcana. Generally I just turn the POS off to allow me to admin my Linux boxes (which are usually behind multiple levels of fires, etc. etc. etc.). This time, I wanted to try to live with it for a while.

Things were going great until I realized I needed to use some space assigned to /home to host some data. So, I setup a directory there (using Location in a an Apache .conf file). I restarted apache with service httpd restart and launched my browser... and got a 500 error.

Well. Well. So, went through the normal hoops - checking for permissions and usernames and lions and tigers and bears oh my. No joy. However, I saw a reference somewhere that SELinux might be causing the problem (which I kinda expected) and that I could test that proposition with setenforce 0. Viola'! It worked!

Of course, the whole reason for this charade was to try to live with SELinux (even though we use trivial passwords behind the firewall) as a learning experience. Hmmmmph. I was starting to regret this already. So, I used setenforce 1 to turn the beast back on, and set off on my quest.

A few googles away, I found the link below, which let me resolve the problem. The magic incantations I recited included the following two lines:

setsebool httpd_enable_homedirs true
chcon -R -t httpd_sys_content_t .


I was able to view the current extended attributes for SE by using:
ls -alZ

I'll include the entire blog post as a help to others, but there was no way I was gonna chmod 777 on the directories to make this work! Now, if I could just figure out WHERE those magic incantations come from, without having to learn 1,000 pages of arcana that don't really matter.

David Latham: Allow httpd ( apache ) to write to files and folde...: You may have read my previous post about configuring apache for public_html with selinux. Now today we look at extending this a little wit...

Cool page talking about Linux RAM usage

So, first, I've been using Linux for a really, really, really long time. Like... 1994. I had to hack a SCSI driver to get my Adaptec 2940W working. Yeah, I know - bragging, right?

I've been using top for even longer - it was a good friend on AIX, HPUX, etc. And I've certainly peeked at /proc/meminfo a few times. But something I never really new existed until recently was a cool command line tool called "free". And more to the point, I never knew something really, really basic about memory usage on Linux.

I stumbled across this page, and had to smile at the title:
Linux Ate My RAM!

It definitely opened my eyes about something I hadn't spent much time thinking about, so - thanks!
free -m... it's your friend.