NAME¶
dchroot-dsa - enter a chroot environment
SYNOPSIS¶
dchroot-dsa [
-h|
--help |
-V|
--version |
-l|
--list |
-i|
--info |
--config |
-p|
--listpaths] [
-d
directory|
--directory=directory]
[
-q|
--quiet |
-v|
--verbose] [
-c
chroot|
--chroot=chroot |
--all |
CHROOT] [
COMMAND]
DESCRIPTION¶
dchroot-dsa allows the user to run a command or a login shell in a chroot
environment. If no command is specified, a login shell will be started in the
user's home directory inside the chroot.
The user's environment will be preserved inside the chroot.
The command is a single argument which must be an absolute path to the program.
Additional options are not permitted.
The directory the command or login shell is run in depends upon the context. See
--directory option below for a complete description.
This version of dchroot-dsa is a compatibility wrapper around the
schroot(1) program. It is provided for backward compatibility with the
dchroot-dsa command-line options, but schroot is recommended for future use.
See the section “
Incompatibilities” below for known
incompatibilities with older versions of dchroot-dsa.
OPTIONS¶
dchroot-dsa accepts the following options:
Basic options¶
- -h, --help
- Show help summary.
- -a, --all
- Select all chroots. Note that earlier versions of
dchroot-dsa did not include this option.
- -c, --chroot=chroot
- Specify a chroot to use. This option may be used multiple
times to specify more than one chroot, in which case its effect is similar
to --all. If this option is not used, the first non-option argument
specified the chroot to use. Note that earlier versions of dchroot-dsa did
not include this option.
- -l, --list
- List all available chroots.
- -i, --info
- Print detailed information about the available chroots.
Note that earlier versions of dchroot-dsa did not include this
option.
- -p, --listpaths
- Print absolute locations (paths) of the available
chroots.
- --config
- Print configuration of the available chroots. This is
useful for testing that the configuration in use is the same as the
configuration file. Any comments in the original file will be missing.
Note that earlier versions of dchroot-dsa did not include this
option.
- -d, --directory=directory
- Change to directory inside the chroot before running
the command or login shell. If directory is not available,
dchroot-dsa will exit with an error status.
- The default behaviour (all directory paths are inside the
chroot) is to run the login shell or command in the user's home directory,
or / if the home directory is not available. If none of the
directories are available, dchroot-dsa will exit with an error
status.
- -q, --quiet
- Print only essential messages. Note that earlier versions
of dchroot-dsa did not include this option.
- -v, --verbose
- Print all messages. Note that earlier versions of
dchroot-dsa did not include this option.
- -V, --version
- Print version information.
CONFIGURATION¶
INCOMPATIBILITIES¶
Debian dchroot prior to version 1.5.1¶
- •
- This version of dchroot-dsa uses schroot.conf to
store the configuration for available chroots, rather than the
dchroot.conf file used historically. dchroot-dsa supported
automatic migration of dchroot.conf to the schroot.conf
keyfile format with its --config option from versions 0.2.2 to
1.5.0; support for the old format is now no longer available.
DSA dchroot¶
- •
- Log messages are worded and formatted differently.
- •
- dchroot-dsa provides a restricted subset of the
functionality implemented by schroot, but is still schroot
underneath. Thus dchroot-dsa is still subject to schroot security
checking, including PAM authentication and authorisation, and session
management, for example, and hence may behave slightly differently to
earlier versions of dchroot-dsa in some circumstances.
Debian dchroot¶
A
dchroot package provides an alternative dchroot implementation.
- •
- All the above incompatibilities apply.
- •
- This version of dchroot has incompatible command-line
options, and while some of those options are supported or have equivalent
options by a different name, the -c option is required to specify a
chroot. It also allows a shell script to be used as the option instead of
a single absolute path, and allows multiple command options instead of a
single option.
DIRECTORY FALLBACKS¶
dchroot-dsa will select an appropriate directory to use within the chroot based
upon whether the
--directory option is used. When explicitly specifying
a directory, only one directory will be used for safety and consistency, while
for a login shell or command several possibilities may be tried. Note that due
to multiple fallbacks being considered for commands, it is dangerous to run
commands using dchroot-dsa; use schroot instead. The following subsections
list the fallback sequence for each case. CWD is the current working
directory, DIR is the directory specified with
--directory.
Login shell or command¶
Transition |
|
(Host → Chroot) |
Comment |
|
CWD → passwd pw_dir |
Normal behaviour (if --directory is not used) |
CWD → / |
If passwd pw_dir is nonexistent |
FAIL |
If / is nonexistent |
--directory used¶
Transition |
|
(Host → Chroot) |
Comment |
|
CWD → DIR |
Normal behaviour |
FAIL |
If DIR is nonexistent |
No fallbacks should exist under any circumstances.
Debugging¶
Note that
--debug=notice will show the internal fallback list computed
for the session.
EXAMPLES¶
$ dchroot-dsa -l↵
Available chroots: sarge, sid
$ dchroot-dsa --listpaths↵
/srv/chroot/sarge
/srv/chroot/sid
$ dchroot-dsa -q sid -- /bin/uname↵
Linux
$ dchroot-dsa sid↵
I: [sid chroot] Running login shell: “/bin/bash”
$
Note that the top line was echoed to standard error, and the remaining lines to
standard output. This is intentional, so that program output from commands run
in the chroot may be piped and redirected as required; the data will be the
same as if the command was run directly on the host system.
TROUBLESHOOTING¶
If something is not working, and it's not clear from the error messages what is
wrong, try using the
--debug=level option to turn on debugging
messages. This gives a great deal more information. Valid debug levels are
‘none’, and ‘notice’, ‘info’,
‘warning’ and ‘critical’ in order of increasing
severity. The lower the severity level, the more output.
If you are still having trouble, the developers may be contacted on the mailing
list:
Debian buildd-tools Developers
<buildd-tools-devel@lists.alioth.debian.org>
BUGS¶
On the
mips and
mipsel architectures, Linux kernels up to and
including at least version 2.6.17 have broken
personality(2) support,
which results in a failure to set the personality. This will be seen as an
“Operation not permitted” (EPERM) error. To work around this
problem, set
personality to ‘undefined’, or upgrade to a
more recent kernel.
FILES¶
- /etc/schroot/schroot.conf
- The system-wide schroot definition file. This file
must be owned by the root user, and not be writable by other.
AUTHORS¶
Roger Leigh.
This implementation of dchroot-dsa uses the same command-line options as the
dchroot found on machines run by the Debian System Administrators for
the Debian Project. These machines have a
dchroot-dsa source package
which provides a
dchroot-dsa package, written by Ben Collins
<bcollins@debian.org> and Martin Schulze <joey@debian.org>.
COPYRIGHT¶
Copyright © 2005-2012 Roger Leigh <rleigh@debian.org>
dchroot-dsa 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),
sbuild(1),
chroot(2),
schroot-setup(5),
schroot.conf(5).