Question

I’m using knoppix 7.0.3 and trying to set the PATH environment variable. According to the official Ubuntu documentation, /etc/environment should be the preferred place for this. So I added these lines in the file:

JAVA_HOME="/usr/lib/jvm/java-6-sun"
GRAILS_HOME="/home/knoppix/grails"
PATH="${PATH}:${JAVA_HOME}/bin:${GRAILS_HOME}/bin"

But after rebooting the system, the file just reverted to the original one (I was using persistent storage).
Then after some Googling, I tried to edit ~/.profile like this:

export JAVA_HOME="/usr/lib/jvm/java-6-sun"
export GRAILS_HOME="/home/knoppix/grails"
export PATH=$PATH:$JAVA_HOME/bin:$GRAILS_HOME/bin

This time, the first two variables got set (echoed in console), but the PATH didn’t. It was still the default one when I echoed. What’s wrong?

Answer 1

The problem is that your PATH is being overwritten during initialization of bash, after reading .profile.

From the manpage of bash:

When bash is invoked as an interactive login shell, or as a non-interactive shell with the –login option, it first reads and executes commands from the file /etc/profile, if that file exists. After reading that file, it looks for ~/.bash_profile, ~/.bash_login, and ~/.profile, in that order, and reads and executes commands from the first one that exists and is readable. The –noprofile option may be used when the shell is started to inhibit this behavior.

…

When an interactive shell that is not a login shell is started, bash reads and executes commands from ~/.bashrc, if that file exists. This may be inhibited by using the –norc option. The –rcfile file option will force bash to read and execute commands from file instead of ~/.bashrc.

From your experience, it is apparent that if .bashrc doesn’t exist, bash is trying to set PATH to a default value (I would appreciate if someone confirms this).

As we discussed in the comments on your question, adding the export commands to .bashrc (and thus creating the file) solves the problem. Alternatively, you can add

source ~/.profile

to the end of your .bashrc file for the same effect.