Archive for Ubuntu

Shell tricks: shorthands

Even with tab completion, typing long commands is tedious. But, there’s something even worst: typing the same long commands again, and again, and again… So how do you solve that? It’s simple: you shorten them. Surprising, uh? Okay enough theory, let me show you some examples.

Here’s a tedious command of Type-A:

% sudo aptitude install zsh

Look at it carefully since you will need to hunt these long commands down until none remains. Now, let me explain how you execute a such command. Open up your personal shell initialization file (e.g. ~/.bashrc for Bash, ~/.zshrc for Zsh, etc). Then, add the following:

alias spkgi="sudo aptitude install"

Reload your shell and finally, enjoy:

% spkgi zsh

Now I can introduce, as you can deduce, other shorten commands that you can produce and reproduce:

# Package Management
alias pkg="aptitude"
alias spkg="sudo aptitude"
alias spkgi="sudo aptitude install"
alias spkgu="sudo aptitude safe-upgrade"
alias spkgr="sudo aptitude remove"
alias spkgd="sudo apt-get build-dep"

# Miscellaneous Helpers
alias nc="rlwrap nc"
alias e=$EDITOR
alias se=sudoedit
alias reload="source ~/.zshrc"
alias g=egrep

Next after Type-A tedious commands, we have the Type-S ones. To execute these, you will you need some sort of special shell support. So, here’s some examples of the Type-S monstrosity:

% find Lib/ -name '*.c' -print0 | xargs -0 grep ^PyErr
% find -name '*.html' -print0 | xargs -0 rename 's/\.html$/.var/'
% find -name '*.patch' -print0 | xargs -0 -I {} cp {} patches/

I hope you start to see some patterns (if you don’t, then try harder). The first one could (and should) be rewritten as:

% rgrep --include='*.c' ^PyErr Lib/

But that isn’t short enough for me, so I have a short helper:

    shift 2
    grep -Er --include=$filepat $pat ${@:-.}
# In Zsh, 'noglob' turns off globing.
# (e.g, "noglob echo *" outputs "*")
alias rg='noglob rg'

It is lovely to use:

% rg *.c ^PyErr Lib/
% rg *.c PyErr_Restore . -C 10 | less
% rg *.[ch] stringlib
% rg *.c ^[a-zA-Z]*_dealloc Modules/ Objects/

The second example is quite similar to the previous one. However, the find/rename combination is much less common (at least for me) than the find/grep one. This one needs to be broken in pieces. One obvious thing to factor out is the find -name with an alias:

alias fname="noglob find -name"

Using this alias, you can rewrite the second example as:

% fname *.html -print0 | xargs -0 rename 's/\.html$/.var/'

It’s better, but it’s not short enough yet. The ugly part of this command is the -print0 | xargs -0. I hate to type that. Wouldn’t it be nice if we could define an alias for it? How about:

alias each="-print0 | xargs -0"

Unfortunately, that doesn’t work since aliases are only expanded if they are in the command position. Luckly, Zsh has that neat feature called global aliases, which does exactly what we want.

alias -g each="-print0 | xargs -0"

With this feature of Zsh, the second example become:

% fname *.html each rename 's/\.html$/.var/'

Now, we can also attack the third one:

% fname *.patch each -I {} cp {} patches/

It is possible to shorten a bit by defining another alias combining each and -I {}, but that won’t make a big difference.

Finally, there are the Type-R tedious commands. These are hard to avoid, unless you’re careful. Here’s again some ridiculous examples to help you recognize these redundant commands:

% gcc -o stackgrow stackgrow.c
% pkg show emacs-snapshot-bin-common emacs-snapshot-common emacs-snapshot-gtk emacs-snapshot
% cat ../lispref.patch ../lwlib.patch ../etc.patch | patch -p1

To reduce these, you don’t need change your shell configuration; you change your habits instead. Using alternations (which are non-standard, but supported by most shells), you can rewrite the two first example as:

% gcc -o stackgrow{,.c}
% pkg show emacs-snapshot{{-bin,}-common,-gtk,}

Now, you are surely asking yourself: “what is different about the third one?” Well, think about it. Got it? No? Ah, come on, it is easy. Here’s a hint:

% echo 'cat ../{lispref,lwlib,etc}.patch | patch -p1' | wc -c
% echo 'cat ../lispref.patch ../lwlib.patch ../etc.patch | patch -p1' | wc -c

You like my hint, don’t you? Here’s the answer:

% echo 'cat ../li\t ../lw\t ../et\t | patch -p1' | wc -c

Tab completion doesn’t work well with prefix alternations. Even if the command using alternation is shorter, it still doesn’t beat good old tab completion.

And that’s all folks. I surely have plenty of other tricks to show, but that will be for the other posts of this short series.

Pretty Emacs Reloaded

Update: If you are using Ubuntu 8.04 LTS “Hardy Heron” or Ubuntu 8.10 “Intrepid Ibex”, use the packages in the PPA of the Ubuntu Emacs Lisp team, instead of the packages referenced here. For Ubuntu 9.04 “Jaunty Jackalope” and newer, use the packages in Ubuntu repositories.

My popular1 Pretty Emacs package just got a tad better. I transferred the package to the brand new PPA service provided by Launchpad. So, what’s new about the package? First, I glad to announce the long-awaited amd64 support. Also, I am adding Gutsy Gibbon to the list of supported distributions.

To use the updated package on Ubuntu 6.10 “Edgy Eft”, add the

following lines to your /etc/apt/sources.list file:

deb edgy main
deb-src edgy main

To use the package on Ubuntu 7.04 “Feisty Fawn”, add the following lines to your /etc/apt/sources.list file:

deb feisty main
deb-src feisty main

To use the package on the development version of Ubuntu “Gutsy Gibbon”, add the following lines to your /etc/apt/sources.list file:

deb gutsy main
deb-src gutsy main

Unfortunately, if you still use Ubuntu 6.06 "Dapper Drake", you will have to keep using the older package release from my orignal repository. I still support Ubuntu 6.06, but I won't update the package with newer snapshots.

After adding the repository to your software source list, upgrade your version of the package with:

sudo aptitude upgrade

If you do not have a previous version of the package already installed and you desire to install it, do this instead:

sudo aptitude install emacs-snapshot emacs-snapshot-el

When upgrading the package you might get the following warning message:

WARNING: untrusted versions of the following packages will be installed!

Untrusted packages could compromise your system's security. You should only proceed with the installation if you are certain that this is what you want to do.

This is due to a bug in the PPA system. I believe that it will be resolved quickly. So, you can safely ignore the warning message for the moment.

Final note, thank you everyone for trusting me and giving me some great feedback about the package. I like to give special thanks to Romain Francoise and Michael Olson for their work respectively on emacs-snapshot and emacs22, during this summer.

  1. A rough estimate tell me there is over 30 000 people using my package, where 88% of them are Feisty Fawn users and 11% are Edgy Eft users. 

Minor annoyance with Planet

Do you know how to fix Planet or WordPress, so when I edit an old post it does not pop back on Planet?

I do edit some of my posts, in particular the Pretty Emacs one, fairly often. I love to have my blog aggregated, but I would hate spamming Planet Ubuntu readers with my old posts. Therefore if I cannot fix this little annoyance, I will have no other choice to remove myself from Planet Ubuntu.

Am I dreaming?

Smoked brains for dinner

Today, there will be a special quiz on Python hosted by me, in #ubuntu-trivia on FreeNode, at 20:00 UTC. Most of the quiz will be to write some simple procedures, faster than your opponents. The winner will, of course, get a superb prize — 5 Ubuntu stickers! Obviously, the real prize is the fun that will get during the quiz. And who knows, maybe you will learn a few neat tricks. So, see you there!

Flipping bits this summer

Dear Applicant, Congratulations! This email is being sent to inform you that your application was accepted to take part in the Summer of Code.

Today, I am truly happy. I wasn’t expecting to be accepted, really, and perhaps no other candidate did. My accepted project is to merge C and Python implementations of the same interface (i.e., StringIO/cStringIO, Pickle/cPickle, etc), and my mentor is the Python star developer, Brett Cannon. This will be a challenging project; I will have to work hard and efficiently to be successful. But one thing is sure, I will have some great fun.

I would like to congrats everyone who have been accepted. A special thanks to students who will be working on Ubuntu, this summer. There is surely some great projects for Ubuntu. And also, another special thanks to the mentors, who will be helping us this summer.

Welcome to Mr. Crystal Ball

As some of you may already know, I am a die-hard fan of productive editing. That is probably because I don’t find myself very fast, on a keyboard. So, I am always trying to find ways to improve my editing speed. And when I ain’t surfing on the web, I am either typing stuff in my shell or my editor. So today, I would like to share a few tricks I uses in my default shell, Z Shell.

The shell history can be a powerful tool. If you find yourself typing commands again, and again, and again, you probably can use it at your advantage. You probably already know about Ctrl+R, which is bound to history-incremental-search-backward command in most shells. Personally, I don’t find it very useful since it tries to find a match everywhere, but it’s better than cycling through the history with the Up/Down keys. In fact, anything is better than the Up/Down keys. So, why not rebind them to something more useful, like history-search-backward? Well, that is easy. With Zsh, you need to add these two line to your .zshrc:

bindkey '\e[A' history-search-backward
bindkey '\e[B' history-search-forward

In fact, if you’re using Emacs key-bindings, you don’t even need to do anything, because Meta+P and Meta+N are already bound to these two functions. Incidentally, Steven Harms is advocating to enable this feature by default in Ubuntu, for Bash’s users. Personally, I am not sure if it’s really necessary to make it a default. I am not a fan of modifications in .inputrc, either. But, I will leave that discussion for another blog post.

Now, that we have functional Up/Down arrow keys, can we do more? Yes, we can! Let me introduce one of my favorite features of Zsh, preemptive auto-completion. If you’re tired typing TAB a zillion times a day, you will love this one. This feature implements predictive typing using history search and auto-completion. Again, to enable it, just copy these lines to your configuration file:

autoload predict-on
zle -N predict-on
zle -N predict-off
bindkey '^Z'   predict-on
bindkey '^X^Z' predict-off
zstyle ':predict' verbose true

Here, note that predict-on and predict-off, are bounded to Ctrl+Z and Ctrl+X Z respectively. That means you can turn it on/off, whenever you need to. You will find useful to turn it off when you edit the middle of a command, since it can confuse the prediction. But other than that, it’s great.

Sometime, the shell editor is not enough for me — I need something more powerful when I edit long commands. So, I use another cool built in function of Zsh, called edit-command-line. With this feature, I can edit the current command with an external editor, defined by the environment variable $EDITOR. To enable it, just copy-and-paste this:

autoload edit-command-line
zle -N edit-command-line
bindkey '^Xe' edit-command-line

So, when I think the command will be long, like a for-loop. I just press Ctrl+X e, which launches, on my system, emacsclient. I am always running Emacs with its server, therefore the shell command is instantaneously loaded into a Emacs buffer. Then when I am done, I close the Emacs session with Ctrl+x # and the command appears in my shell. It is just sweet.

Even if you’re a master with your editor, nothing beats a short alias, or a shell script. I keep a full directory of useful scripts, to automate my daily tasks. At first, writing scripts feels a bit awkward. If you’re like me, you will always worry that your scripts might go terribly wrong, and eat your data. That’s totally normal, but don’t be a fool. Automating your tasks, even the most trivial ones, will save some of your precious time. Unlike scripts, which can really do some heavy automation, aliases are just a shell convenience, like auto-completion. Personally, I am not a big fan of fancy aliases. (I tend to use functions for the more fancy things.) Anyway, here some of my favourite aliases:

# Set up aliases
alias c=clear
alias d='dirs -v'
alias e=$EDITOR
alias grep=egrep
alias h=history
alias j=jobs
alias po=popd
alias pu=pushd
alias ss='screen -Rx'

# Global aliases -- These do not have to be
# at the beginning of the command line.
alias -g M='|more'
alias -g L='|less'
alias -g H='|head'
alias -g T='|tail'

# Go to parent directories without `cd'
setopt autocd
alias -g ...='../..'
alias -g ....='../../..'
alias -g .....='../../../..'

I certainly have a ton of shell tricks, but I will keep them for my other blog posts. So, that’s all folks!

Back in Business

A burned video, a zapped hard drive and a corrupt RAM module later , I have now, finally, got my system running again (and no, my computer was not struck by a lightning).

For the fans of my Emacs package, I just uploaded a new release, and I will continue to provide weekly releases. Unfortunately, it seems, due to a licensing issue, Romain Francoise orphaned emacs-snapshot and its related packages. Therefore, this means I will have to work harder and fix packaging bugs myself, instead of relying on his bug fixes.

A week before I lost my system, I had promised a special Python quiz, in the issue #31 of Ubuntu Weekly News. I have not forgotten my promise. So if you’re one of the lovers my twisted Ubuntu quizzes, get ready for an awesome quiz. Date and time, when the quiz will be held, will be announced, as usual, in the #ubuntu-trivia channel on FreeNode.

On the final note, I would like to mention that will start posting more frequently on my blog. My current roadmap includes some cool tips-and-tricks, fun script recipes, more stuff about Ubuntu. So, stay tuned!

Debian Packaging 101 (Part 1)

Making packages for Debian derivatives (like Ubuntu) isn’t really hard. It just required some dedication to learn how the packaging system work. Yet, most users don’t know how to make packages for their distribution. In this series, I will try to give a brief introduction packaging.

First, I would like to tell you that, if you never compiled a program before, this short guide will be useless for you. Therefore, I assume that you know and that you did compile a program before. Also, I will use the term “package” to refer to the compiled program package ready to installed on Debian or its derivatives. And, I will use the term “program” to refer to the software, like “GNU Emacs”.

A package consists of two things: the source code of a program and a debian/ directory which contains information how to build the program. There is different methods to specify the packaging information. The most common one, and the one I will discuss here, is using a tool called debhelper. This tool makes the packaging process easier by abstracting the common packaging tasks into little scripts, run at the build time. The typical directory structure of a package looks like this:


Obviously, this example is simplified, but you get the idea. That are the interesting things for a packager. By the way, GNU Hello a good example of package to study. You get it with:

$ apt-get source hello-debhelper

Here, a quick description of the files in the debian/ directory:

  • changelog: The history of the package’s changes.
  • compat: A file that contains the debhelper version that is used.
  • control: The description of the package and the list of dependencies.
  • copyright: A copy of the licence the program uses.
  • postinst: A post-installation script used to setup things after the package has been unpacked.
  • prerm: Another script that is run before the removal of the package. It usually used to undo the things postinst has done.
  • rules: The instructions how to build the package. This is simply a Makefile.

In more complicated programs, there is usually other files. However, I won’t talk about them in this introduction. Anyway, I am out of time. In the second part of this series, I will explain the tools used to build packages.

Pretty Emacs

Update: If you are using Ubuntu 8.04 LTS “Hardy Heron” or Ubuntu 8.10 “Intrepid Ibex”, use the packages in the PPA of the Ubuntu Emacs Lisp team, instead of the packages referenced here. For Ubuntu 9.04 “Jaunty Jackalope” and newer, use the packages in Ubuntu repositories.

Emacs is my editor of choice. In fact, I should say it’s my framework of choice, but that’s for another post. Until recently, I disliked the poor font backend of Emacs. So, I was always using Emacs within a terminal window to get a decent looking interface. However, this grungy font era is over, since Emacs’s hackers added recently to my favorite editor a XFont backend, thus making possible to use good looking fonts, like Bitstream Vera Sans Mono.

Screenshot of Emacs with XFT support

I made a package that makes the installation, as painless as possible. So, feel free to use it. However, please note that this is an alpha release of Emacs, therefore it should only be used for testing. (From my experience, it’s rock solid.)

Still interested? Then, here the instructions. First, add my repository into your software source list, by adding the following lines to /etc/apt/sources.list:

deb feisty main
deb-src feisty main

If you are running Ubuntu 6.10 (Edgy Eft) or the current development version of Ubuntu (Gutsy Gibbon), change feisty for edgy or gutsy.

Finally, run either apt-get or aptitude to fetch and install the packages:

sudo aptitude update
sudo aptitude install emacs-snapshot emacs-snapshot-el

Now, you need to specify the font you want to use in your Xresources file.

echo "Emacs.font: Monospace-10" >> ~/.Xresources
xrdb -merge ~/.Xresources

Here, I use the default monospace font, but any other monospaced font should work too. For example, if you want to use Lucida Sans Typewriter instead, change Monospace-10 for Lucida Sans Typewriter-10 in the above command.

And that’s it! Now, launch Emacs and enjoy the good looking fonts.

If you need support with the package, just email me at

Update: Il y a, maintenant, une version en français de ce guide sur le wiki de Ubuntu-fr.