On 8 January 2016 at 08:44, Yi Zhao wrote: > It still need to escape quotation marks if using -F option. > Consider the following log: > [521514.737] (EE) evdev: Qemu Tablet: Unable to open evdev device > "/dev/input/touchscreen0". > > We still need an extra step to replace " with \" before grep > Actually that's only true as the grep command is passed to subproces.check_output() as a string. If it was constructed as a list the shell wouldn't be parsing it and you wouldn't have to worry about quoting at all. (always pass lists instead of strings to subprocess, it makes everything a lot easier) Ross