This method seems to be easier, but needs node.js. Is it necessary to dive into node.js to run it ? I'm a beginner programmer and don't know if it's a good idea to go in node.js while being still learning javascript...

a few weeks after stopping thinking to this problem, I come back ! In fact, I'm struggling hard to "fiddle" this pathing problem. I tried to directely overwrite wih fcList[count] = arcpy.Erase...but it put the out fc at the end of the list. Then I delete the fcList[0] and replace it by the last one, but it seems that the list of characters is independent from the real layer. The change in the list does not infer on the real fc. I don't know what try anymore, if somebody has some ideas, it would be much appreciated. Bye

Ok I found the problem, and it works well. thanks for support

this script which was working well is now unusable without changing anything. I have a new error alert "porow is not defined". I don't understand because it seems well defined in python synthax and was working 2 days ago...Any idea ?

the running of your code generates the following error : "module object has no attribute 'GetParamterAsText'". Hence, I really don't understand why you want modify the if part of the code...This part has been tested and tested and it works fine and if I don't do a mistake, has no effect on parameters...My problem is only the setting of parameters. I just can't understand why GetParameterAsText don't make my parameters variables.

To be clearer, I edit my first post with the complete code.

@MichaelMiles-Stimson I don't want to overwrite anything. I simply want to use any existing geodatabase, any existing clip shapefile, and any existing out folder.Are you sure is it GetParameterAsText ?

@artwork21 I have the good .py file referenced.