Bad Bash Sourcing

Zachary Lund — Wed, 11 Mar 2009 23:32:18 +0000

A while back I switched such that my .bash_profile sources my .bashrc instead of the reverse. Based on a few sources, this seems to be the preferred approach. Today I decided to push those files to a few servers that haven’t been updated lately. I transferred my .bash_profile and then my .bashrc:

zac@dakara:~$ scp ~/.environment/bash/bash_profile lansky:~/.bash_profile
bash_profile                                  100%  120     0.1KB/s   00:00
zac@dakara:~$ scp ~/.environment/bash/bashrc lansky:~/.bashrc
lost connection

What happened? My .bash_profile sources my .bashrc, but since I hadn’t yet replaced the .bashrc, it still sources my .bash_profile. That means infinite loop and that I am an idiot. SSH, rsync, and scp are all broken. There is no way to remove or replace either of those files without another account. I guess it’s time to open a support ticket at DreamHost.

The moral of the story is to always be careful how you source those files. I usually try to keep an SSH session open on the remote machine when I modify those files in case I break login, but this time I didn’t. A few searches didn’t reveal any solutions. I’d love to know if someone has a way of resolving this without access to another account on the remote machine.

Advanced Bash Completion

Zachary Lund — Sun, 22 Feb 2009 22:42:50 +0000

Ubuntu has a lot of advanced bash completion features that simplify using the shell. For example, when using the ssh command, I can tab complete server names based on my host file and my ssh config file. It turns out that most of this is accomplished with one bash_completion script. This page has a lot of useful information about the Bash shell and also the very useful script. I’ve found that when I use Fedora in the Xinu lab, I am left typing a lot of this stuff myself. Since I use the same bashrc file on both Dakara and my lab machine (Kastria), I didn’t want to always resource the file so I added this to my bashrc:

# Source global definitions
[ -f /etc/bashrc ]      && source /etc/bashrc
[ -f /etc/bash.bashrc ] && source /etc/bash.bashrc
# enable programmable completion features
if [ -z "$BASH_COMPLETION" \
    -a -r ~/.configuration/bash/bash_completion.caliban ]; then
    BASH_COMPLETION=~/.configuration/bash/bash_completion.caliban
    source $BASH_COMPLETION
fi

First, I source the global definitions, Ubuntu uses /etc/bashrc, and Fedora uses /etc/bash.bashrc. After that, if the bash_completion script was already sourced, $BASH_COMPLETION will be set. I check to see if it is zero length (-z) and then source my own copy of it if it is. Now I have advanced bash completion on both Ubuntu and Fedora.

blog.lundscape.com » bashrc

Bad Bash Sourcing

Advanced Bash Completion