Thankfully, the Internets are here to help. A knowledgeable bloke going by Jalada knows his business. He knows what o’clock it is, I dare say.

The short of it is, Lion comes with some gimcrack modern rubbish known as LLVM, whereas you need the right honorable Admiral Lord GCC. If your MBP or MBA was made after the dinosaurs went extinct, you probably don’t have pure, undiluted GCC. As per the previous link’s comments, simply go here, snag the ‘OS X 10.6 Snow Leopard: GCC-10.6.pkg’ package, install it, and Bob’s yer uncle Dick. That is to say, you’ll have proper GCC slumming about at /usr/bin/gcc-4.2.

After that, simply append ‘CC=/usr/bin/gcc-4.2′ before your RVM installations. (EG, ‘CC=/usr/bin/gcc-4.2 rvm install 1.8.7′)

…This sort of nonsense, though, is why I despise the idea of local development; indeed, I avoid it whenever possible. But as the current fancy du jour involves building standardized virtualized machines for developers (thus avoiding this sort of issue, and more importantly, ‘hurr, works on my machine!!!!1111eleven’ syndrome), well, my hand is forced. Yo dawg, I herd u like virtualization, but we can’t put a virtual box in your virtual box. Really.

As root:

yum --exclude=*.i?86 install -y gcc-c++ patch readline readline-devel zlib zlib-devel libyaml-devel libffi-devel openssl-devel make bzip2 autoconf automake libtool bison curl

As your Ruby-happy user:

echo insecure >> ~/.curlrc
bash -s stable < <(curl -s https://raw.github.com/wayneeseguin/rvm/master/binscripts/rvm-installer)
echo '[[ -s "$HOME/.rvm/scripts/rvm" ]] && . "$HOME/.rvm/scripts/rvm" # Load RVM function' >> ~/.bash_profile
source .bash_profile
rvm install 1.9.2
rvm use 1.9.2
rvm use 1.9.2 --default
rvm gemset create rails3
rvm gemset use rails3
gem install rails

Note: Curl on RHEL5 is braindead when it comes to SSL – thus, you need to basically force Curl to not authenticate certificates by way of the insecure method.

Can it be that simple?

# ruby --version
ruby 1.9.2p290 (2011-07-09 revision 32553) [x86_64-linux]
# rails --version
Rails 3.1.3

I’m not going to stop cringing at the idea of taking software version control out of the hands of your distribution’s package management system. It’s the wrong thing to do. It’s always the wrong thing to do, even when it’s the right thing to do (hi, content management systems living in a docroot).

Still, props to RVM. It’s been blissfully easy to work with, and at least has clear upgrade paths/capabilities, even if they do reside outside of the rest of the system.

At any rate, congratulations on running the unarguably superior Linux distribution. Here’s some things you should know.

RHEL Version and Alternatives

RHEL5 vs RHEL6

There’s only one viable reason to go with RHEL5 at this point: You’re deploying a new server to an existing cluster of RHEL5 servers.

Other than that, you should now be using RHEL6. It’s past the initial release phase; it’s been out long enough to have proven itself stable; and by virtue of being a later version, it’ll be supported longer than RHEL5.

Distribution Alternatives

My advice? Don’t. But if you have to?

For many years, CentOS has been the “free” compatible alternative of choice for RHEL. There’s been concern over update frequency/lag time behind RHEL of late. Some have been looking at Scientific Linux as a result, but you can expect a visit from John Titor if you go down that route.

Where My Packages At?

Third party repositories are a necessity with RHEL. The fact is, developers are all whiny about new features and sharp pointy things they can injure themselves and your infrastructure with. Best to just give them what they want – and with RHEL, you can, while maintaining your sanity.

MySQL

If you’re running MySQL, you have no excuse whatsoever to not be running Percona. Percona is the Bugatti Veyron of MySQL, whereas every distributions’ default MySQL packages are nothing more than a bunch of Honda Accords. Percona Server is a drop-in replacement; your data is unaffected and you can revert to conventional MySQL at any time with no risk. Percona offers consulting and on-demand support; they’ve got enterprise paranoia, err, needs, covered. Percona currently offers 5.1 and 5.5 variants; there’s little reason not to go with 5.5 these days. I think they have Ubuntu packages now too, for you crazy kids who are into kinky stuff.

PHP

If you’re running PHP, Zend CE is the answer. Ever wonder how to get PHP 5.2 on a RHEL5 system without using packages that haven’t been maintained in a year? Or perhaps you just want PHP to actually be, you know, fast. Install Zend CE and you’ll have a well-documented, well-supported, optimized-to-hell-and-back PHP stack, from Zend. From freaking Zend, people. Zend CE currently offers PHP 5.2 and 5.3 flavors.

Ruby

Ruby’s the new Perl (and then some); and like the good old days of Perl, there’s an overinflated version hell problem. Unlike Perl, Ruby isn’t old enough to have stabilized to the point where you can run what your distribution provides and be happy. rbel.frameos.org may be the answer here – if and only if you’re working with Ruby 1.8. If you are, you can look forward to a repository filled with 1.8 goodness as well as things like Chef and Node.

If you want to run with 1.9? Good luck with that. The only viable option I’ve found so far is RVM, which lends itself to operational nightmares. (“Let’s make thirty two copies of this out of date gem with a security vulnerability! That’s easy to update, right?”)

I’m starting to suspect Ruby is nothing more than an insidious exit plan for exhausted sysadmins. Learn Rails, become overpaid; welpguesssomeoneelseneedstoberesponsibleforuptimeImtoobusydeveloping. Genius.

Everything Else

EPEL is your answer for all those miscellaneous packages, such as git and whatnot.

Problem is, I can’t migrate their docroots. Well, I can grab most of the docroots – but curiously, there’s a number of files which are owned by apache:apache and -rx to anything but, wull, Apache.

The virtual server in question has no root access, no sudo, and no way to configure either through their control panel. Last time I had the misfortune of dealing with GoDaddy’s support… Let’s just say, I don’t have three days for another non-resolution.

What to do? Wull, it is a Drupal site…

<?php
system('/bin/chmod -R go+rx /path/to/files', $retval);
?>

This happily worked, because everything I needed to mess with was owned by the Apache user, so Apache itself had no problems smacking permissions around.

This pointedly wouldn’t have worked if a different user (root, for example) had ownership of those files. But never underestimate the power of a single call to system() and the weird headaches it might solve.

Assert error in main(), varnishd.c line 632: Condition((daemon(1, d_flag)) == 0) not true. errno = 19 (No such device

The reason was that /dev/null was a bit… wonky. To fix this, I did:

rm /dev/null
mknod -m 666 /dev/null c 1 3

Really confused as to how /dev/null could go wonky – that is, break – that is, look like a normal freaking file, but eh, there you have it.

Initial login was sucessful, the ‘Last logged in…’ line displayed, but after that nothing but a blinking cursor. Commands could be entered, but nothing would execute, and no bash prompt was seen.

The problem was quickly fixed with a strategic rsync, but let this be a lesson:

If you’re messing with root’s bash prompt, either test it on a non-root user, or open a second session to test. I was quite taken aback by this, because it didn’t dawn on me that it was possible to break bash to such a degree via a simple prompt modification.

I either need more or less coffee. I haven’t yet decided which.

Anyhow, say you’ve got a file with ICANHAZCHEEZBURGRZ somewhere in it, and you want to replace that hilarious phrase. Here’s what you do:

sed -i 's/ICANHAZCHEEZBURGRZ/IHAZACHEEZBURGR/' filename

This will replace ‘ICANHAZCHEEZBURGRZ’ with ‘IHAZACHEEZBURGR’.

Such a thing is extremely useful when scripting the configuration of an insane amount of systems. (*wink wink, nudge nudge*)