schroot 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
by using the same style of execution as
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 'setup-stop' option.
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
Note that the scripts should be idempotent. They must be
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 as.
The host system architecture schroot is running upon. This may be used to
introduce architecture-specific behaviour into the setup scripts where
required. HOST is the GNU triplet for the architecture, while HOST_OS,
HOST_VENDOR and HOST_CPU are the component parts of the triplet.
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
Set to 'true' if a session will be created, otherwise 'false'.
Set to 'true' if a session will be cloned, otherwise 'false'.
Set to 'true' if a session will be purged, 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 snapshots).
The name of the chroot. This is useful for restricting a setup task to a
particular chroot, or set of chroots.
The description of the chroot.
The location to mount the chroot. It is used for mount point creation and
The location of the chroot inside the mount point. This is to allow multiple
chroots on a single filesystem. Set for all mountable chroot types.
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.
Plain and directory chroot variables
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'.
Mountable chroot variables
These variables are only set for directly mountable chroot types.
The device to mount containing the chroot.
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
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 /etc/schroot/copyfiles-defaults.
A file in the format decribed in
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
The directory /etc/schroot/setup.d contains the chroot setup scripts.
Print debugging diagnostics and perform basic sanity checking.
Unpack, clean up, and repack file-based chroots.
Create and remove union filesystems.
Create and remove LVM snapshots.
Mount and unmount filesystems.
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 example.
Configure system databases by copying passwd, shadow, group etc. into the
Set the chroot name (/etc/debian_chroot) in the chroot. This may be used
by the shell prompt to display the current chroot.
schroot 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