My PATH variable was changed accidently and now I cant find any commands on my termin
 

I accidently changed my PATH variable and now i cant find any commands on my terminal .I am using Debian.How to solve this problem??
I also need to know how to give priority to java 6 if i hav both java 5 and java 6 installed in debian??

Where you change the PATH variable?

To give more priority to java 6 add the path to java 6 bin before java 5 bin

I think the PATH variable will be restored when you boot up.

Maybe a little unrelated, but even without a PATH, you can still access commands by typing their full path, like:

Which of your commands are you trying to access?

Unless you've backed up your profile somewhere; you'd need to have knowledge of exactly where the binaries are located for each of your apps (if not in /usr/bin; /usr/sbin).

Perhaps post the contents of /home/youruser/.bash_profile - this will indicate if you've completely lost your PATH.

I typed something like
export $JAVA_HOME= /home/username/...../jdk1.6.0_18
export $PATH=$PATH:JAVA_HOME/bin
in my .bashrc file inorder to set classpath for my java 6.
After setting it, i couldnt find my commands..

I used a similar thing to add /home/username/bin to my $PATH, but I did it quite differently, and I put in in my .bash_profile instead of my .bashrc:

I see I used "VAR=" instead of "export $VAR=", I wonder if that could be it.

MTK could be right, if that also does not work, just remove these lines from your .bash_profile file and see if your commands start working.

In this example, it should have been:
export $PATH=$PATH:$JAVA_HOME/bin

Convention says use quotes on the right-hand side of =, but I just tried without quotes and it did not seem to matter.

And, don't use $ when assigning the variable---should be:
JAVA_HOME= /home/username/...../jdk1.6.0_18

Remove this $

So I guess the solution for the OP would be to remove what he but in his .bashrc and put this in his .bash_profile:

I don't know what the "....." is, just replace it by what you meant.

Is there a typo in that? Should it not be (as suggested for export JAVA=...)It was prudent in earlier shells (in case there was whitespace in the value of $PATH) but is not necessary in recent (all?) bash versions because bash does not do word splitting on the expression to the right of an assignment "=".

Sorry----I fixed two errors in the original, but missed the third one

Assigning variables:
varname=<stuff>

Using variables:
<stuff>=$varname <other stuff>