LD_LIBRARY_PATH problem

[marcel]

What shell are you using?
For bash, the user startup script is ~/.bash_profile (or ~/.bashrc ).
You can add there the export and it will be set when you log in.

You also have to check /etc/passwd and make sure your user's default shell is bash.

For other shells, just search the internet.

Also why LD_LIBRARY_PATH suddenly disappear from my export list after a few hours?

There must be some voodoo involved .
Really, I think you run some application that just changes the variable. This shouldn't happen, it should append paths to the var not override it.