Installing the Io Language in Ubuntu

words by Brian Racer

I have recently begun reading through Bruce Tate’s fun Seven Languages In Seven Weeks book. One of the chapters focuses the Io language and it’s installation can be a little bit non-standard to get it to my liking.

Generally on my development machine when I compile from source I like to install locally to my home directory rather than system wide. This way sudo privileges are not needed plus I just like the idea of keeping these items close to home.

First Io requires the cmake build system so make sure that is available.

$ sudo apt-get install cmake

Next download and extract the source code.

$ wget --no-check-certificate -O
$ unzip
$ cd stevedekorte-io-[hash]

Io provides a build script, however it is setup to install the language to /usr/local. Since I want it to go in $HOME/local you just need to modify that file. Here is a quick one liner:

$ sed -i -e 's/^INSTALL_PREFIX="\/usr\/local/INSTALL_PREFIX="$HOME\/local/'

Now build and install.

$ ./
$ ./ install

Since we are installing into a location our OS doesn’t really know about, we need to configure a few paths.

$ vim ~/.bashrc
export PATH="${HOME}/local/bin:${PATH}"
export LD_LIBRARY_PATH="${HOME}/local/lib:${LD_LIBRARY_PATH}"
# You might want these too
export CPPFLAGS="-I${HOME}/local/include"
export MANPATH="${HOME}/local/share/man:${MANPATH}"

Lastly restart your shell and type ‘io’ and you should be dropped into Io’s REPL!

A side benefit to this method is you can install anything you build into $HOME/local. Usually you just need to pass the –prefix=$HOME/local parameter when you run a ./configure script.

Pretty Paging in Rails Console

words by Brian Racer

When using irb or Rails console I use the awesome_print gem to get nicer colorized output. I also like to use looksee to examine method lookup paths which the gem colorizes nicely. For large objects looksee can produce a lot of output and if there is more output than your terminal can display at once it will get handed off to your system’s pager (probably less). I was having an issue while in Rails console when the output got paged it would show the ANSI color escape codes rather than colorized text (this didn’t happen in irb for whatever reason).

Luckily less has a flag that will repaint the screen when paging. To make it a default you need to export a LESS variable to your shell’s environment. Something like this:

export LESS="-R"

Just throw that in your ~/.bashrc or dotfiles and you’re all set!

Pimp your $PS1 with source control information

words by Brian Racer

I recently found a useful tip of appending source control information of the current working directory to your shell’s $PS1 line. It might look something like the following image:

The method I saw suggested using vcprompt, a small program that outputs a short string basic version control info. Although it worked well, there were a couple issues I had with it. First, it’s subversion support was somewhat lacking. Second, it was written in C which made it more of a pain to modify, and I wasn’t a huge fan of keeping the binary in version control.

After a little searching I stumbled across, a python script that did the same thing. This version also had wider support for source control systems, and being a standard python text script it was something I could easily modify and put into my dotfiles git repo. I wasn’t happy with how this one displayed subversion information either(just a revision number which I didn’t find very helpful), so I made my own modification to display the branch you are in. Please pardon my lacking Python skills.

Anyway, on to pimping your prompt. Before we modify the PS1 variable, we need to make sure the is in your $PATH. I like to put scripts like this in a custom bin directory in my homedir. One way to accomplish that might be the following:

$ mkdir -p ~/bin
$ cd ~/bin
$ wget
$ chmod +x
$ export PATH=~/bin:$PATH

Displayed next is the PS1 line I use – it takes up two lines: the first line contains the current user, hostname, current working directory, and possibly version control info, and the second is just a nice looking arrow for my input. Your terminal will need to support Unicode if you want to use that symbol.

# .bashrc
PS1="\n\u@\h:\w \[\e[1;30m\]$(vcprompt)\[\e[0m\] \n→"
# If you are using zsh you may also need the following in .zshrc
setopt prompt_subst

If you use the colors specified, you may need to define those too.

You should now have a prompt similar to the image above! For more shell customizations checkout the rest of my dotfiles, and consider buying Peepcode’s Advanced Command Line screencasts for more productive tips!