--- name: "schroot-setup" section: "5" platform: "linux" package: "schroot" version: "1.6.13-11" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/schroot-setup" --- # schroot-setup(5) schroot chroot setup scripts ## NAME schroot-setup - schroot chroot setup scripts ## DESCRIPTION **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 [**init**(8)](/init/8.md), by using the same style of execution as [**run-parts**(8)](/run-parts/8.md). The setup scripts are all invoked with two options: - 1 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. - 2 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** be idempotent during the ‘setup-stop’ phase, because they may be run more than once, for example on failure. ## ENVIRONMENT ### General variables - AUTH\_USER The username of the user the command in the chroot will run as. - CHROOT\_NAME The chroot name. Note that this is the name of the original chroot before session creation; you probably want SESSION\_ID. - LIBEXEC\_DIR The directory under which helper programs are located. - MOUNT\_DIR The directory under which non-filesystem chroots are mounted (e.g. block devices and LVM snapshots). - PID The process ID of the schroot process. - PLATFORM 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. - SESSION\_ID The session identifier. - VERBOSE 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. - CHROOT\_SESSION\_CREATE Set to ‘true’ if a session will be created, otherwise ‘false’. - CHROOT\_SESSION\_CLONE Set to ‘true’ if a session will be cloned, otherwise ‘false’. - CHROOT\_SESSION\_PURGE Set to ‘true’ if a session will be purged, otherwise ‘false’. - CHROOT\_SESSION\_SOURCE Set to ‘true’ if a session will be created from a source chroot, otherwise ‘false’. - CHROOT\_TYPE 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). - CHROOT\_NAME The name of the chroot. This is useful for restricting a setup task to a particular chroot, or set of chroots. - CHROOT\_ALIAS 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 unstable chroot. - CHROOT\_DESCRIPTION The description of the chroot. - CHROOT\_MOUNT\_LOCATION The location to mount the chroot. It is used for mount point creation and mounting. - CHROOT\_LOCATION 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. - CHROOT\_PATH 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. ### File variables - CHROOT\_FILE The file containing the chroot files. - CHROOT\_FILE\_REPACK 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. - CHROOT\_MOUNT\_DEVICE The device to mount containing the chroot. - CHROOT\_MOUNT\_OPTIONS Options to pass to [**mount**(8)](/mount/8.md). - CHROOT\_LOCATION The location of the chroot inside the mount point. This allows the existence of multiple chroots on a single filesystem. ### Filesystem union variables - CHROOT\_UNION\_TYPE Union filesystem type. - CHROOT\_UNION\_MOUNT\_OPTIONS Union filesystem mount options. - CHROOT\_UNION\_OVERLAY\_DIRECTORY Union filesystem overlay directory (writable). - CHROOT\_UNION\_UNDERLAY\_DIRECTORY Union filesystem underlay directory (read-only). ### Block device variables - CHROOT\_DEVICE The device containing the chroot root filesystem. This is usually, but not necessarily, the device which will be mounted. For example, for a LVM snapshot this will be the original logical volume. ### LVM snapshot variables - CHROOT\_LVM\_SNAPSHOT\_NAME Snapshot name to pass to [**lvcreate**(8)](/lvcreate/8.md). - CHROOT\_LVM\_SNAPSHOT\_DEVICE The name of the LVM snapshot device. - CHROOT\_LVM\_SNAPSHOT\_OPTIONS Options to pass to [**lvcreate**(8)](/lvcreate/8.md). ### Custom variables Custom keys set in *schroot.conf* will be uppercased and set in the environment as described in [**schroot.conf**(5)](/schroot.conf/5.md). ## FILES ### Setup script configuration The directory ***/etc/schroot/default*** contains the default settings used by setup scripts. - ***config*** Main configuration file read by setup scripts. The format of this file is described in [**schroot-script-config**(5)](/schroot-script-config/5.md). 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: - ***copyfiles*** A list of files to copy into the chroot from the host system. Note that this was formerly named */etc/schroot/copyfiles-defaults*. - ***fstab*** A file in the format described in [**fstab**(5)](/fstab/5.md), used to mount filesystems inside the chroot. The mount location is relative to the root of the chroot. Note that this was formerly named */etc/schroot/mount-defaults*. - ***nssdatabases*** 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*. ### Setup scripts The directory ***/etc/schroot/setup.d*** contains the chroot setup scripts. - ***00check*** Print debugging diagnostics and perform basic sanity checking. - ***05file*** Unpack, clean up, and repack file-based chroots. - ***05fsunion*** Create and remove union filesystems. - ***05lvm*** Create and remove LVM snapshots. - ***10mount*** Mount and unmount filesystems. - ***15binfmt*** 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 whole-machine emulation. - ***15killprocs*** Kill processes still running inside the chroot when ending a session, which would prevent unmounting of filesystems and cleanup of any other resources. - ***20copyfiles*** Copy files from the host system into the chroot. Configure networking by copying *hosts* and *resolv.conf*, for example. - ***20nssdatabases*** Configure system databases by copying passwd, shadow, group etc. into the chroot. - ***50chrootname*** Set the chroot name (*/etc/debian\_chroot*) in the chroot. This may be used by the shell prompt to display the current chroot. ## AUTHORS Roger Leigh. ## COPYRIGHT Copyright © 2005-2012 Roger Leigh `` **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 version. ## SEE ALSO [**schroot**(1)](/schroot/1.md), [**fstab**(5)](/fstab/5.md), [**schroot.conf**(5)](/schroot.conf/5.md), [**schroot-script-config**(5)](/schroot-script-config/5.md), [**run-parts**(8)](/run-parts/8.md).