Often when I’m trying to figure out how to do something in Centos I’ll do the same thing as millions of other programmers and just Google the answer. But for some reason Centos top-hit results seems to have very convoluted answers for things that have much, much easier answers.

Note that I’m currently working with Centos 6.6/6.7. YMMV for other versions.

As a minor example: when you’re new to centos and want to find out how to install the epel repo you end up with guides having you wget or curl an rpm and then using rpm to install it. This top result from Google is one example of this: http://www.tecmint.com/how-to-enable-epel-repository-for-rhel-centos-6-5/

It’s not really that hard to do … and it certainly works …but there’s a way to do it in yum with the install you already have. You could just issue a

sudo yum install epel-release

It’s much the same for trying to figure out how to get a more recent release of python installed on the system. Centos comes with Python 2.6 and sometimes being able to use Python 2.7 or 3.3 would make life so much better. Here’s the top StackOverflow result for this topic: http://stackoverflow.com/questions/10624511/upgrade-python-without-breaking-yum

Those methods certainly work … but what if there was an easier way with just a yum command or two?  Indeed, newer packages are just a yum command away:

yum install centos-release-SCL

Additional information here: https://wiki.centos.org/AdditionalResources/Repositories/SCL
and here: https://www.softwarecollections.org/en/

And Python 2.7.8 – https://www.softwarecollections.org/en/scls/rhscl/python27/

Hope this helps save others some time

Derping around a GUI is all fine and good for many things but sometimes you really just need to get things done and your GUI just won’t cut it. Having a powerful command line interface and being knowing how to use it are critical skills. I’ve recently found myself having to use the command line a bit more than usual, so below are some of the learned or re-learned tidbits of knowledge that might help others.

Note: I’m a Windows developer, but the commands below all use bash in Cygwin.

Q: How can I generate a file of an arbitrary size with random data?

A: Use dd in conjunction with /dev/urandom

# 2 Megs
dd if=/dev/urandom of=a.log bs=1M count=2

# 2 Gigs (1 Meg * 2 * 1024)
dd if=/dev/urandom of=a.log bs=1M count=2K 

Q: How can I sort a file, remove duplicate elements, and do it all in-place?

A: sort temp.txt -o temp.txt

Q: How can I pipe the output from foo.exe to bar.exe if bar.exe does not accept input from stdin?

A: The obvious answer is to redirect stdout to a file then use the file as an input parameter.
(Note: md5sum *does* accept stdin input. Ignore that for the sake of the example)

echo -n hello > temp.dat
md5sum temp.dat
rm temp.dat

The command below can skip the intermediate step.

md5sum <(echo -n hello)

I’ve been on a big reading spree this year. By genre, but otherwise in no particular order:

Non-fiction

Coding Related:

• Effective Programming: More than Writing Code

Career & Self:

• The 7 Habits of Highly Effective People (Stephen R. Covey)
• No Excuses!: The Power of Self Discipline (Brian Tracy)
• Eat that Frog!: 21 Great Ways to Stop Procrastinating and Get More Done in Less Time (Brian Tracy)
• The Now Habit (Neil Fiore)
• Power: Why Some People Have It and Others Don’t (Jeffery Pfeffer)
• Predictably Irrational: The Hidden Forces That Shape Our Decisions (Dan Ariely)
• On Second Thought: Outsmarting Your Mind’s Hard-Wired Habits (Wray Herbert)
• Does This Clutter Make My Butt Look Fat? (Peter Walsh)
• How to Stay Motivated: The Goals Program (Zig Ziglar)
• The Willpower Instinct: How Self-Control Works, Why It Matters, and What You Can Do to Get More of It (Kelly McGonigal)
• Linchpin – Are You Indispensable? (Seth Godin)

Fiction

• Dark Swan Series (Richelle Mead)
  • Storm Born
  • Thorn Queen
  • Iron Crowned
  • Shadow Heir
• The Wise Man’s Fear (Patrick Rothfuss)
• A Dance with Dragons (George R.R. Martin)
• The Farseer Trilogy (Robin Hobb)
  • Assassin’s Apprentice
  • Royal Assassin
  • Assassin’s Quest
• Southern Vampire Mysteries (Charlaine Harris)
  • Dead in the Family
  • Dead Reckoning
  • Deadlocked

Article on Slate calls out those who love to point out when “Correlation does not imply causation.”

http://tinyurl.com/8swrbrw

The C:\Windows\WinSXS directory can get way too big for comfort. On my Win2k8 VMWare image it was 10.9 gigs. On a VMWare image that’s just wasted space. After a little research I settled on a few steps to help me trim the fat down to 6.72 GB:

1. Issued the command: dism /online /cleanup-image /spsuperseded
2.  Install and run CCleaner
3. Delete all the files in C:\windows\winsxs\Backup

Logging in to Stack Overflow today my curiosity about using OpenID got the better of me. I wanted to use my domain name as my login identifier. I quickly found instructions on using my domain with Google as my OpenID provider but I wanted to use myopenid.com

Turns out the process is really easy. The process is covered here: https://www.myopenid.com/help#own_domain

You just add the following tags to your page’s head tag.

<link rel="openid.server" href="http://www.myopenid.com/server" />
<link rel="openid.delegate" href="http://youraccount.myopenid.com/" />
<link rel="openid2.local_id" href="http://youraccount.myopenid.com" />
<link rel="openid2.provider" href="http://www.myopenid.com/server" />
<meta http-equiv="X-XRDS-Location" 
    content="http://www.myopenid.com/xrds?username=youraccount.myopenid.com" />

Voila! You can now use your domain as your login for OpenID!

Some notes I took as I went through trying to compile the C++ driver for mongodb under win32.

• Hit up MongoDB C++ Page
• http://www.mongodb.org/pages/viewpage.action?pageId=133409
• Downloaded driver linked from Driver Download Page & some other prerequisites
• http://downloads.mongodb.org/cxx-driver/mongodb-linux-x86_64-v2.0-latest.tgz
• http://www.mongodb.org/download/attachments/12157032/boost_1_42_vs2010_partial_prebuilt.7z
• Went to C++ Driver Compiling and Linking and scrolled down to Windows
• http://www.mongodb.org/pages/viewpage.action?pageId=21266598

• Hrm. I’d rather not have to mess with scons … so how do I build the lib?
• WTF? I want to try including client/mongo_client_lib.cpp in my project but IT’S NOT IN THE FRAKING ARCHIVE!
• OK. Fine. Let’s fire up git and clone the full git source.
• Ahh…. ok, found mongo_client_lib.cpp. Why the hell even bother putting up the tar ball?
• Loaded simple_client_demo into visual studio.
• Boost missing. Ok .. Let’s set up project to point to proper includes and precompiled libraries
• Holy shit that compiled.
• Fired up MongoDB Shell and created a collection.
• Ran through the debugger. Everything works, but how come code references test.foo but in the shell it shows name is just ‘foo?

• Apparently didn’t need perl regex files? (referenced elsewhere)
• bo and bob? really?! (in bson seralization class)