Patch activate

By default, virtualenv does not set LD_LIBRARY_PATH. This will result in errors when running applications that links to libdlite, like for example, dlite-codegen. To fix this, $VIRTUAL_ENV/lib/ needs to be appended/prepended to LD_LIBRARY_PATH. This is attempted done with the script patch_activate.sh which is run as a part of the installation.

If not successful, this can be done manually by modifying the activate shell file, located at $WORKON_HOME/<envs_name>/bin/activate. First, the user should add

if ! [ -z "${_OLD_LD_LIBRARY_PATH}" ] ; then
    LD_LIBRARY_PATH="$_OLD_LD_LIBRARY_PATH"
    export LD_LIBRARY_PATH
    unset _OLD_LD_LIBRARY_PATH
fi

at the end of the deactivate function in the activate shell file. Next, add

export _OLD_LD_LIBRARY_PATH=$LD_LIBRARY_PATH
export LD_LIBRARY_PATH="$VIRTUAL_ENV/lib/:$LD_LIBRARY_PATH"

at the end of activate.

Explanation: The value of LD_LIBRARY_PATH is exported (saved) into a new temporary environment variable, _OLD_LD_LIBRARY_PATH. $VIRTUAL_ENV/lib/ is then prepended to LD_LIBRARY_PATH. The if statement within the deactivate function checks whether the variable _OLD_LD_LIBRARY_PATH has been declared. If true, then the deactivate function will set LD_LIBRARY_PATH to its original value and unset the temporary environment variable _OLD_LD_LIBRARY_PATH.