I’ve tried many ways to build a clean testing environment for Emacs editor on my Ubuntu machine. One previous attempt showed a possible way to do so:

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$ emacs -Q -l some_startup_script.el

But this solution doesn’t show the real state of affairs when we load all the configuration files in Emacs. The .emacs file is loaded in the middle of the Emacs initialization, not at the end. See for details 39.1.1 Summary: Sequence of Actions at Startup. One possible problem is that package.el loads its configuration before you’ve done custom changes.

For now I consider a better way starting Emacs from another user:

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$ emacs -u emacstestuser

All customizations can be done in the .emacs.d directory from emacstestuser. The only thing you need is changing of user specific variables:

.emacs
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(setq user-emacs-directory "/home/emacstestuser/.emacs.d")

We can face the situation with restricted rights on a server. This is a use case for sudo. You can get restricted access to specific commands as root, but not to the whole system, which is very good!

I need access to virt-top to monitor kvm based virtual machines on a big host system. Add the following line to sudoers file:

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myusername ALL= NOPASSWD: /usr/bin/virt-top

This line allows myusername to run virt-top without password from any terminal.

A couple of useful links:

Today I’ve encountered the problem adding files within a LaTeX project. All generated PDF files are ignored in the project .gitignore:

.gitignore
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*.pdf

I had to add two PDF files with graphics and didn’t want to change my ingnoring rules:

Adding ignored files with Git
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$ git add -f file1.pdf file2.pdf

The -f switch forces Git to add ignored files. Use it!

A new milestone in the Rubinius’ development has been announced on October, 15th. The new project is called Rubinius X and should simplify obstacles in the Ruby world.

Rubinius X aims to create a new industry friendly Ruby environment which should prevent the endangered Ruby language from dying.

On October, 4th the Rubinius team announced the release of Rubinius 2.0. There are many exciting things to share. Look inside Rubinius 2.0!

How to call Java from JRuby?

Calling Java
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require 'java'
java_import my.package.CoolClass

obj1 = Java::CoolClass.new