I am trying to install a overlay filesystem, in order to make the sd-card read-only. I've used this script:
It ran without errors, and it has added "overlay=yes" to my /boot/cmdline.txt:
overlay=yes dwc_otg.lpm_enable=0 console=serial0,115200 console=tty4 root=PARTUUID=fa504fc4-02 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait dtoverlay=pi3-disable-wifi pi3-disable-bt consoleblank=0 logo.nologo logo.nologo quiet splash plymouth.ignore-serial-consoles vt.global_cursor_default=0
but after a reboot, anything written to the fs still seems permanent. Here's the output of df:
Filesystem 1K-blocks Used Available Use% Mounted on /dev/root 15011056 1251204 13117476 9% / devtmpfs 470180 0 470180 0% /dev tmpfs 474788 0 474788 0% /dev/shm tmpfs 474788 12224 462564 3% /run tmpfs 5120 4 5116 1% /run/lock tmpfs 474788 0 474788 0% /sys/fs/cgroup /dev/mmcblk0p1 41853 21328 20525 51% /boot tmpfs 94956 0 94956 0% /run/user/1000
It does seem to have made some tmpfs's, but I must have missed an important step somewhere..
Update: after adding "noswap fastboot ro" to /boot/cmdline.txt and editing /etc/fstab, the root and /boot fs now indeed are mounted readonly.
The remaining problem now is the programs I want to run, are to write to the readonly fs. for instance: xauth: error in locking authority file /home/pi/.Xauthority Should I somehow change the homerdir? and what about /tmp and /var ?