$ vi $HOME/.bash_profile
export JAVA_HOME=/usr/lib/jvm/java-6-sun
export PATH=$PATH:$JAVA_HOME/bin

$ cd /etc

/etc$ ls -a
............
profile
profile.d
............

$vi profile
# /etc/profile: system-wide .profile file for the Bourne shell (sh(1))
# and Bourne compatible shells (bash(1), ksh(1), ash(1), ...).
if [ -d /etc/profile.d ]; then
for i in /etc/profile.d/*.sh; do
if [ -r $i ]; then
. $i
fi
done
unset i
fi
if [ "$PS1" ]; then
if [ "$BASH" ]; then
PS1='\u@\h:\w\$ '
if [ -f /etc/bash.bashrc ]; then
. /etc/bash.bashrc
fi
else
if [ "`id -u`" -eq 0 ]; then
PS1='# '
else
PS1='$ '
fi
fi
fi

$ source ~/.bash_profile
bash: /home/eyesonly/.bash_profile: No such file or directory

$ echo $JAVA_HOME
path/jdk1.6.0_14/

$ echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:path/jdk1.6.0_14/

$ which java
/usr/bin/java

$ java -version
java version "1.6.0_14"
Java(TM) SE Runtime Environment (build 1.6.0_14-b08)
Java HotSpot(TM) Client VM (build 14.0-b16, mixed mode, sharing)

$ export JAVA_HOME=/usr/lib/jvm/java-6-sun-1.6.0.14/bin
$ PATH=$PATH:/usr/lib/jvm/java-6-sun-1.6.0.14/bin

$ cd /usr/lib/jvm/
/usr/lib/jvm$ ls -l
total 4
lrwxrwxrwx 1 root root 19 2009-08-31 15:45 java-6-sun -> java-6-sun-1.6.0.14
drwxrwxrwx 6 root root 4096 2009-08-31 15:45 java-6-sun-1.6.0.14

$ javac
The program 'javac' can be found in the following packages:
* openjdk-6-jdk
* ecj
* gcj-4.3
* java-gcj-compat-dev
* gcj-4.2
* jikes-classpath
* jikes-kaffe
* kaffe
* sun-java5-jdk
* sun-java6-jdk
Try: sudo apt-get install <selected package>
bash: javac: command not found