===== Read-Only SD Card =====

If one needs a Raspberry Pi that shuts down save by just unplugging and without having the risk of corrupting the SD card one has to change the SD card to a read-only mode.\\

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==== Drives ====
In the fstab:
  $ sudo nano /etc/fstab
one has to change the SD card to read only (ro) and one has to make a temporary virtual drive (30MB), too:
  /dev/mmcblk0p2  /               ext4    defaults,noatime,ro  0       1
  tmpfs           /tmp            tmpfs   defaults,size=30M    0       0

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==== Disable some Programs ====
One has to disable some programs,  rsyslog and dphys-swapfile:\\

  $ sudo systemctl disable rsyslog
  $ sudo systemctl disable dphys-swapfile

If one needs a programs that requires writing one has to make sure that will be in the temporary drive. That could be done for example with a symbolic link:
  $ ln -s /home/pi/tmp /tmp

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==== Remount ====

For changes in the system one has to remount the partition writable:\\
  $ sudo mount / -o remount,rw

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==== Links ====

[[http://raspberrypi.stackexchange.com/questions/5112/running-on-read-only-sd-card]]\\
[[https://web.archive.org/web/20150101110424/http://raspberrycenter.de/forum/umruestung-raspberry-pi-read-only-root-filesystem]]\\

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