Hi, im new in mel and run in to a problem. i made attached paint effects grass with autopaint-paint random to plane. i get a lot of strokes whch is fine. but to convert them in to polys, it's usually better to check output quads in strokeShape-mesh output. But as i have about 800 strokes it would be much easier to select them in the script editor all together. 
To select a singel one and check the output quads its:
select -r stroke1 ;
setAttr "strokeShape1.meshQuadOutput" 1;

now i dont know how to selct them all with a command

can anyone help me please

Select your strokes and execute this in the python tab of your scriptEditor

1

2

3

4

import maya.cmds as cmds

selectedStrokes = cmds.ls(selection=True, dag=True, shapes=True)

for eachStroke in selectedStrokes:

    cmds.setAttr((eachStroke+".meshQuadOutput"), 1)