Fix arrow keys in IRB in Ubuntu

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Fix arrow keys in IRB in Ubuntu

February 19th, 2009

Issue

If you’re a rails programmer in Ubuntu, odds are you’re going to encounter some issues while trying to use your arrow keys inside IRB (Interactive Ruby), and this particular problem will also affect script/console.

Arrow keys don’t work in IRB
Can’t load script/console

Symptoms

If you try to launch your console, the following errors will appear. As you can tell, we’ve got a library missing – “readline”.

 script/console
Loading development environment (Rails 2.2.2)
/usr/local/lib/ruby/1.8/irb/completion.rb:10:in `require': no such file to load -- readline (LoadError)
	from /usr/local/lib/ruby/1.8/irb/completion.rb:10
	from /usr/local/lib/ruby/1.8/irb/init.rb:252:in `require'
	from /usr/local/lib/ruby/1.8/irb/init.rb:252:in `load_modules'
	from /usr/local/lib/ruby/1.8/irb/init.rb:250:in `each'
	from /usr/local/lib/ruby/1.8/irb/init.rb:250:in `load_modules'
	from /usr/local/lib/ruby/1.8/irb/init.rb:21:in `setup'
	from /usr/local/lib/ruby/1.8/irb.rb:54:in `start'
	from /usr/local/bin/irb:13

Fix

Marinate your keyboard with some Dr. Pepper. For best results, use beer. NO! Buy a MAC. NO! I joke . MACS are expensive.

Fix it this way:

Install the readline library: sudo apt-get install libreadline5 libreadline5-dev
Compile the library: cd into the “ext/readline” inside your ruby installation. It’s probably under “/usr/local/src”, but you’ll definitely need to figure this one on your own.
sudo ruby extconf.rb
sudo make
sudo make install
Re-launch IRB and script/console and it should work!