schroot-setup - schroot chroot setup scripts
uses scripts to set up and then clean up the chroot environment.
The directory /etc/schroot/setup.d
contains scripts run when a
chroot is created and destroyed. Several environment variables are set while
the scripts are being run, which allows their behaviour to be customised,
depending upon, for example, the type of chroot in use.
The scripts are run in name order, like those run by init
(8), by using
the same style of execution as run-parts
The setup scripts are all invoked with two options:
- The action to perform.
- When a session is first started, the chroot is set up by
running the scripts in /etc/schroot/setup.d with the
‘setup-start’ option. When the session is ended, the scripts
in /etc/schroot/setup.d are run in reverse order with the
- The chroot status.
- This is either ‘ok’ if there are no problems,
or ‘fail’ if something went wrong. For example, particular
actions may be skipped on failure.
Note that the scripts should be idempotent
. They must
idempotent during the ‘setup-stop’ phase, because they may be
run more than once, for example on failure.
- The username of the user the command in the chroot will run
- The chroot name. Note that this is the name of the orignal
chroot before session creation; you probably want SESSION_ID.
- The directory under which helper programs are located.
- The directory under which non-filesystem chroots are
mounted (e.g. block devices and LVM snapshots).
- The process ID of the schroot process.
- The operating system platform schroot is running upon. This
may be used to introduce platform-specific behaviour into the setup
scripts where required. Note that the HOST variables are probably what are
required. In the context of schroot, the platform is the supported
configuration and behaviour for a given architecture, and may be identical
between different architectures.
- The session identifier.
- Set to ‘quiet’ if only error messages should
be printed, ‘normal’ if other messages may be printed as
well, and ‘verbose’ if all messages may be printed.
Previously called AUTH_VERBOSITY.
- Set to ‘true’ if a session will be created,
- Set to ‘true’ if a session will be cloned,
- Set to ‘true’ if a session will be purged,
- Set to ‘true’ if a session will be created
from a source chroot, otherwise ‘false’.
- The type of the chroot. This is useful for restricting a
setup task to particular types of chroot (e.g. only block devices or LVM
- The name of the chroot. This is useful for restricting a
setup task to a particular chroot, or set of chroots.
- The name of the alias used to select the chroot. This is
useful for specialising a setup task based upon one of its alternative
alias names, or the default chroot name. For example, it could be used to
specify additional sources in /etc/apt/sources.list, such as a
stable-security alias for a stable chroot, or an experimental alias for an
- The description of the chroot.
- The location to mount the chroot. It is used for mount
point creation and mounting.
- The location of the chroot inside the mount point. This is
to allow multiple chroots on a single filesystem. Set for all mountable
- The absolute path to the chroot. This is typically
CHROOT_MOUNT_LOCATION and CHROOT_LOCATION concatenated together. This is
the path which should be used to access the chroots.
These chroot types use only general variables.
- The file containing the chroot files.
- Set to ‘true’ to repack the chroot into an
archive file on ending a session, otherwise ‘false’.
These variables are only set for directly mountable chroot types.
- The device to mount containing the chroot. mounting.
- Options to pass to mount(8).
- The location of the chroot inside the mount point. This
allows the existence of multiple chroots on a single filesystem.
- Union filesystem type.
- Union filesystem mount options.
- Union filesystem overlay directory (writable).
- Union filesystem underlay directory (read-only).
- The device containing the chroot root filesystem. This is
usually, but not necessarily, the device which will be mounted. For
example, an LVM snapshot this will be the original logical volume.
- Snapshot name to pass to lvcreate(8).
- The name of the LVM snapshot device.
- Options to pass to lvcreate(8).
Custom keys set in schroot.conf
will be uppercased and set in the
environment as described in schroot.conf
The directory /etc/schroot/default
contains the default settings
used by setup scripts.
- Main configuration file read by setup scripts. The format
of this file is described in schroot-script-config(5). This is the
default value for the script-config key. Note that this was
formerly named /etc/schroot/script-defaults. The following files
are referenced by default:
- A list of files to copy into the chroot from the host
system. Note that this was formerly named
- A file in the format decribed in fstab(5), used to
mount filesystems inside the chroot. The mount location is relative to the
root of the chroot. Note that this was formerly named
- System databases (as described in /etc/nsswitch.conf
on GNU/Linux systems) to copy into the chroot from the host. Note that
this was formerly named /etc/schroot/nssdatabases-defaults.
The directory /etc/schroot/setup.d
contains the chroot setup
- Print debugging diagnostics and perform basic sanity
- Unpack, clean up, and repack file-based chroots.
- Create and remove union filesystems.
- Create and remove LVM snapshots.
- Mount and unmount filesystems.
- Sets up the QEMU user emulator using binfmt-support. This
permits a chroot for a different CPU architecture to be used
transparently, providing an alternative to cross-compiling or
- Kill processes still running inside the chroot when ending
a session, which would prevent unmounting of filesystems and cleanup of
any other resources.
- Copy files from the host system into the chroot. Configure
networking by copying hosts and resolv.conf, for
- Configure system databases by copying passwd, shadow, group
etc. into the chroot.
- Set the chroot name (/etc/debian_chroot) in the
chroot. This may be used by the shell prompt to display the current
Copyright © 2005-2012 Roger Leigh <firstname.lastname@example.org>
is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later