Downgrading packages in Arch Linux

On occasion (actually today was the first time) there is need to downgrade a package in Arch Linux. Yesterday I did a `pacman -Syu`, which upgraded gcc from 4.4.3 to 4.5.0. Today, I learned that 4.5.0 is unable to compile Moab. You'd think that a new release of your trusty compiler would work at least as good as the last one, but that's a topic (spelled R-A-N-T) for another day. When this catastrophe strikes, you can do the following to recover.

1. On my Arch system, package files are kept in /var/cache/pacman/pkg. Go there.

2. Find the desired package. In this particular case, /var/log/pacman.log told me that yesterday I upgraded from 4.4.3-2 to 4.5.0-1. So my working compiler up until yesterday was gcc 4.4.3.

3. "Upgrade" to the desired package: `pacman -U gcc-4.4.3-2-x86_64.pkg.tar.xz` and `pacman -U gcc-libs-4.4.3-2-x86_64.pkg.tar.xz`

4. Also in my case I'll want to stick with gcc 4.4.3 for a while now, so you can modify the IgnorePkg line in /etc/pacman.conf as follows:

IgnorePkg = gcc gcc-libs

This causes pacman to skip over gcc and gcc-libs when you do a system-wide upgrade (mine prints a warning to say it's being ignored, which I don't consider to be a bad thing).

Terminal colors, all-day readability, and Arch Linux

A recent system upgrade broke my terminal colors. I don't know what exactly it was, or how it happened, but I opened a new terminal window, did a `ls`, and all my directories were bold and blue again. I personally find this difficult to read as I use a very dark blue background in my terminals (something on the order of #111133).

The solution:

Run the following command to create a default dir_colors file (the file that generates the colors for the ls command):

    `dircolors -p > ~/.dir_colors`

Then, add the following to your .bashrc file:

    # set the TERM variable to a color-enabled type (xterm-color)
 export TERM="xterm-color"

 # source my own .dir_colors file
 if [ -f $HOME/.dir_colors ]
 then
     eval `dircolors -b $HOME/.dir_colors
 fi

This will allow you to customize what colors describe what objects for the ls command.

I personally make the following changes in ~/.dir_colors:

- DIR 01;34
+ DIR 00;36 # directories are cyan and non-bold

Then, I go through and turn off bold (swap 00 for 01) for almost everything. The only things I leave bold are executables and sym/hardlinks. For more info on dir_colors, see

    man dircolors

or

    man dir_colors