Add or Update the Fstab File

In KIWI, all major filesystems that were created at image build time are handled by KIWI itself and setup in /etc/fstab. Thus there is usually no need to add entries or change the ones added by KIWI. However depending on where the image is deployed later it might be required to pre-populate fstab entries that are unknown at the time the image is build.

Possible use cases are for example:

  • Adding NFS locations that should be mounted at boot time. Using autofs would be an alternative to avoid additional entries to fstab. The information about the NFS location will make this image specific to the target network. This will be independent of the mount method, either fstab or the automount map has to provide it.

  • Adding or changing entries in a read-only root system which becomes effective on first boot but can’t be added at that time because of the read-only characteristics.

Note

Modifications to the fstab file are a critical change. If done wrongly the risk exists that the system will not boot. In addition this type of modification makes the image specific to its target and creates a dependency to the target hardware, network, etc… Thus this feature should be used with care.

The optimal way to provide custom fstab information is through a package. If this can’t be done the files can also be provided via the overlay file tree of the image description.

KIWI supports two ways to modify the contents of the /etc/fstab file:

  1. Providing an /etc/fstab.append file

    If that file exists in the image root tree, KIWI will take its contents and append it to the existing /etc/fstab file. The provided /etc/fstab.append file will be deleted after successful modification.

  2. Providing an /etc/fstab.patch file

    The /etc/fstab.patch represents a patch file that will be applied to /etc/fstab using the patch program. This method also allows to change the existing contents of /etc/fstab. On success /etc/fstab.patch will be deleted.

Note

/etc/fstab.append and /etc/fstab.patch can be used together. If both files are provided, appending happens first and patching afterwards.