roslaunch. Passing parameters via command line

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Hello all, I am performing the tutorial Customizing the Stage Simulator and I am facing issues with the following command line:

roslaunch turtlebot_stage turtlebot_in_stage.launch map_file:="~/stageTutorial/tutorial.yaml" world_file:="~/stageTutorial/tutorial.world"

When I execute it, the following erros occurs:

[FATAL] [1455317172.700221865]: The world file ~/stageTutorial/tutorial.world does not exist.

and

[ERROR] [1455317069.732110275]: Map_server could not open ~/stageTutorial/tutorial.yaml.

Nevertheless, the directory stageTutorial and both files tutorial.world and tutorial.yaml exist.

This behavior becomes weirder because of the fact that when I export the path of both files to the turtlebot environment variables the launch file behaves as expected. The cited commands are:

export TURTLEBOT_STAGE_MAP_FILE=~/stageTutorial/tutorial.yaml
export TURTLEBOT_STAGE_WORLD_FILE=~/stageTutorial/tutorial.world
roslaunch turtlebot_stage turtlebot_in_stage.launch

I do not have any clue about what is wrong and it is important to mention that the code was copied from a ros' tutorial without any change. So, here is my question: How can I run the fist roslaunch command correctly?

Thanks in advance.