NAME

bootc-install-mount - Mount an installed deployment into a caller-owned directory

SYNOPSIS

bootc install mount --sysroot=SYSROOT --latest [--read-only] TARGET

DESCRIPTION

Mount the deployment from an offline physical sysroot, such as one just created by bootc install to-filesystem, at TARGET. Both the OSTree and composefs backends are supported. TARGET is an absolute path to a directory; as with mount(8), whatever is there is hidden (bootc warns if it is not empty).

A deployment selector is required; currently the only one is --latest. For now the sysroot must also contain exactly one deployment, as it does right after installation; otherwise bootc refuses to guess which one to mount. Requiring the selector leaves room to choose among multiple deployments in the future without changing what existing invocations mean.

The mount remains in the caller's mount namespace after this command exits; bootc does not create a container, chroot, or private mount namespace.

The root follows what the initramfs does at boot. For composefs it is the deployment's image. For OSTree it is the deployment's composefs image (.ostree.cfs), mounted as ostree-prepare-root(1) does, unless prepare-root.conf sets composefs.enabled = no or the deployment has no image, in which case it is the deployment directory itself. Unlike ostree-prepare-root, bootc also uses the image when composefs.enabled is unset, does not consult kernel arguments, and for signed only requires fs-verity without checking the commit signature.

The deployment root and /usr are always read-only. The persistent /etc and /var are writable, unless --read-only is specified. The caller owns the resulting mount tree and should clean it up recursively with umount -R.

/etc and /var are set up the way the deployment's root setup will mount them at boot: for composefs as configured by bootc-setup-root-conf(5), and for OSTree following etc.transient in prepare-root.conf. A transient /etc is a fresh overlay of the image's /etc, so changes to it are discarded on unmount, just as they would be on reboot. A transient root (root.transient) is not applied; the root stays read-only.

/var is always the deployment's state directory on SYSROOT. bootc does not look in the image or its configuration (such as /etc/fstab or systemd mount units) for a separate /var filesystem, and does not consider kernel arguments such as systemd.volatile. If the installation puts /var on its own partition, mount that on top of TARGET/var yourself.

Plain chroot(1) into TARGET is not enough to run programs from the deployment: it sets up no /proc, /sys, /dev or /run. Use a tool that provides those, such as bwrap, podman run --rootfs, or systemd-nspawn(1).

OPTIONS

TARGET

Directory receiving the deployment mount

This argument is required.

--sysroot=SYSROOT

Offline target sysroot

--latest

Mount the latest deployment. Currently the sysroot must contain exactly one

--read-only

Mount /etc and /var read-only too. The deployment root is always read-only

EXAMPLES

Mount an installation and modify its persistent configuration and state:

mkdir /mnt/installed
bootc install mount --sysroot /mnt/sysroot --latest /mnt/installed
install -D -m 0644 hostname /mnt/installed/etc/hostname
umount -R /mnt/installed

VERSION

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