dchroot-dsa - Online in the Cloud

PROGRAM:

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
<[email protected]>

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