Reading the files on the External SdCard

Hi all,
With the M20 command, I can list the files in the onboard SDcard on smoothieboard (the one with the "config.txt to be clear), if I connect an external sdcard reader to the SPI port without the reprap display I can see from the serial terminal connected to the USB port that smoothieboard recognize the Sd card when inserted to the ext. reader.
Which command(or syntax) I need to list the external sd card files as I do with the main one?
Thanks

Imported from wikidot

ls /ext/
should work

Heii,
Thanks a lot!!!

Ok, the syntax works perfectly, thanks a lot!
Now I typed M32 ls /ext/ file.gcode (the name of the file)

But I get the error: file.open error ls /ext/ namefile.gcode.
What I’m doing wrong? which one is the correct syntax?
Thank you for the help

Try
play /ext/file.gcode

Perfect, thanks!!