In my .cshrc, the LD_LIBRARY_PATH was originally like this:
setenv LD_LIBRARY_PATH path_one:$LD_LIBRARY_PATH
setenv LD_LIBRARY_PATH path_two:$LD_LIBRARY_PATH
% echo $LD_LIBRARY_PATH
When you source your file that assignment line is being run. It is prepending that static value to the current value of the
Source the file three times in a row and you'll add that path to the front three times.
There isn't a "default" value you can revert to (unless you save one yourself and be careful with it). In short you get to log out and log back in again or manually edit the current value to be what you want it to be (by manually using
setenv from the running shell
echo "$LD_LIBRARY_PATH" to get the current value and copy and paste from it, etc.).
That being said there isn't any real harm in having an extra path in
$LD_LIBRARY_PATH when it doesn't exist. It just costs an open attempt during application startup (but that should be fairly quick).
If the path does exist and contains libraries you don't want to use that's a different story of course.