Replace /boot/cmdline.txt on RPi2

Question

I seem to have messed up /boot/cmdline.txt while trying to edit it to get GPS working under UART.

I now cannot access the Pi.

Is there a way to replace the file on the SD card without using the PI and without starting from scratch and rewriting the SD card

Thanks. Alan

Answer 1

Yes, there is a way to update cmdline.txt without starting again. The SD card has a partition with the name boot. I was able to plug the card into my laptop (a Mac, but the partition is FAT so it opens on Windows too) and edit cmdline.txt.

Below is what my working line looks like:

dwc_otg.lpm_enable=0 console=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p6 rootfstype=ext4 elevator=deadline rootwait

Answer 2

As long as you are not using NOOBS you should just be able to edit cmdline.txt on a Windows PC (it is on the partition visible to Windows).

The single line contents of mine is

dwc_otg.lpm_enable=0 console=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait

Answer 3

Thanks to you all. I tried the NOOBS recovery by using shift and that allowed me to boot and edit. I will look for the boot partition on the SD card later.

For those who are as stupid as me the command line is just that - one line so you cannot split it up on to several lines which is what it looks like when it appears in an answer (see below)!!!

My pi is RPi2 so the correct original line is :

dwc_otg.lpm_enable=0 console=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p6 rootfstype=ext4 elevator=deadline rootwait