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NAME | SYNOPSIS | DESCRIPTION | COMMANDS | COMMAND TAGS | JSON OUTPUT | SEE ALSO | COLOPHON |
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DH_ASSISTANT(1) Debhelper DH_ASSISTANT(1)
dh_assistant - tool for supporting debhelper tools and provide
introspection
dh_assistant command [additional options]
dh_assistant is a debhelper program that provides introspection
into the debhelper stack to assist third-party tools (e.g.
linters) or third-party debhelper implementations not using the
debhelper script API (e.g., because they are not written in
Perl).
The dh_assistant supports the following commands:
active-compat-level (AJSON)
Synopsis: dh_assistant active-compat-level
Outputs information about which compat level the package is
using.
For packages without valid debhelper compatibility information
(whether missing, ambiguous, not supported or simply invalid),
this command operates on a "best effort" basis and may abort when
error instead of providing data.
The returned JSON dictionary contains the following key-value
pairs:
active-compat-level
The compat level that debhelper will be using. This is the
same as DH_COMPAT when present or else declared-compat-level.
This can be null when no compat level can be detected.
declared-compat-level
The compat level that the package declared as its default
compat level. This can be null if the package does not
declare any compat level at all.
declared-compat-level-source
Defines how the compat level was declared. This is null (for
the same reason as declared-compat-level) or one of:
debian/compat
The compatibility level was declared in the first line
debian/compat file.
X-DH-Compat: <C>
The compatibility was declared in the debian/control via
a the X-DH-Compat field. In the output, the C is replaced
by the actual compatibility level. A full example value
would be:
X-DH-Compat: 15
Build-Depends: debhelper-compat (= <C>)
The compatibility was declared in the debian/control via
a build dependency on the debhelper-compat (= <C>)
package in the Build-Depends field. In the output, the C
is replaced by the actual compatibility level. A full
example value would be:
Build-Depends: debhelper-compat (= 15)
supported-compat-levels (AJSON, CRFA)
Synopsis: dh_assistant supported-compat-levels
Outputs information about which compat levels, this build of
debhelper knows about.
This command accepts no options or arguments.
which-build-system (AJSON)
Synopsis: dh_assistant which-build-system [build step]
[build system options]
Output information about which build system would be used for a
particular build step. The build step must be one of configure,
build, test, install or clean and must be the first argument
after which-build-system when provided. If omitted, it defaults
to configure as it is the most reliable step to use auto-
detection on in a clean source directory. Note that build steps
do not always agree when using auto-detection - particularly if
the configure step has not been run.
Additionally, the clean step can also provide "surprising"
results for builds that rely on a separate build directory. In
such cases, debhelper will return the first build system that
uses a separate build directory rather than the one build system
that configure would detect. This is generally a cosmetic issue
as both build systems are all basically a glorified rm -fr
builddir and more precise detection is functionally irrelevant as
far as debhelper is concerned.
The option accepts all debhelper build system arguments - i.e.,
options you can pass to all of the dh_auto_* commands plus (for
the install step) the --destdir option. These options affect the
output and auto-detection in various ways. Passing -S or
--buildsystem overrides the auto-detection (as it does for
dh_auto_*) but it still provides introspection into the chosen
build system.
Things that are useful to know about the output:
• The key build-system is the build system that would be used
by debhelper for the given step (with the given options,
debhelper compat level, environment variables and the given
working directory). When -S and --buildsystem are omitted,
this is the result of debhelper's auto-detection logic.
The value is valid as a parameter for the --buildsystem
option.
The special value none is used to denote that no build system
would be used. This value is not present in --list parameter
for the dh_auto_* commands, but since debhelper/12.9 the
value is accepted for the --buildsystem option.
Note that auto-detection is subject to limitations in regards
to third-party build systems. While debhelper does support
auto-detecting some third-party build systems, they must be
installed for the detection to work. If they are not
installed, the detection logic silently skips that build
system (often resulting in build-system being none in the
output).
• The build-directory and buildpath values serve different but
related purposes. The build-directory generally mirrors the
--builddirectory option where as buildpath is the output
directory that debhelper will use. Therefore the former will
often be null when --builddirectory has not been passed while
the latter will generally not be null (except when build-
system is none).
• The dest-directory (--destdir) is undefined for all build
steps except the install build step (will be output as null
or absent). For the same reason, --destdir should only be
passed for install build step.
Note that if not specified, this value is currently null by
default.
• The parallel value is subject to DEB_BUILD_OPTIONS. Notably,
if that does not include the parallel keyword, then parallel
field in the output will always be 1.
• Most fields in the output can be null. Particular if there
is no build system is detected (or when --buildsystem=none).
Additionally, many of the fields can be null even if there is
a build system if the build system does not use/set/define
that variable.
detect-hook-targets (EXEC, AJSON)
Synopsis: dh_assistant detect-hook-targets
Detects possible override targets and hook targets that dh(1)
might use (provided that the relevant command is in the
sequence).
**UNSAFE**: This command relies on the output of make. Even it
its dry-run mode, make may execute commands from debian/rules.
Avoid using on packages from untrusted sources, where you have
not reviewed the packaging for backdoors.
The detection is based on scanning the rules file for any target
that might look like a hook target and can therefore list targets
that are in fact not hook targets (or are but will never be
triggered for other reasons).
The detection uses a similar logic for scanning the rules file
and is therefore subject to makefile conditionals (i.e., the
truth value of makefile conditionals can change whether a hook
target is visible in the output of this command). In theory, you
would have to setup up the environment to look like it would
during a build for getting the most accurate output. Though, a
lot of packages will not have conditional hook targets, so the
"out of the box" behaviour will work well in most cases.
The output looks something like this:
{
"commands-not-in-path": [
"dh_foo"
],
"hook-targets": [
{
"command": "dh_strip_nondeterminism",
"is-empty": true,
"package-section-param": null,
"filename": "debian/rules",
"target-name": "override_dh_strip_nondeterminism"
},
{
"command": "dh_foo",
"is-empty": false,
"package-section-param": "-a",
"filename": "debian/rules",
"target-name": "override_dh_foo-arch"
}
]
}
In more details:
commands-not-in-path
This attribute lists all the commands related to hook
targets, which dh_assistant could not find in PATH. These
are usually caused by either the command not being installed
on the system where dh_assistant is run or by the command not
existing at all.
If you are using this command to verify an hook target is
present, please double check that the command is spelled
correctly.
hook-targets
List over hook targets found along with additional
information about them.
command
Attribute that lists which command this hook target is
related too.
target-name
The actual target name detected in the debian/rules file.
is-empty
A boolean that determines whether dh(1) will optimize the
hook out at runtime (see "Completely empty targets" in
dh(1)). Note that empty override targets will still cause
dh(1) to skip the original command.
package-section-param
This attribute defines what package selection parameter
should be passed to dh_* commands used in the hook
target. It can either be -a, -i or (if no parameter
should be used) "null".
filename
This attribute reports which file the target was found
it. In most cases, this will always be "debian/rules"
though in case of include files, the target could appear
in an include file. Note this attribute is not super
reliable as make(1) only reports it for targets with a
"recipe" (targets with commands inside them). When make
does not provide the filename, dh_assistant blindly
assumes the filename is "debian/rules" (as overrides via
includes is not a commonly used feature).
Note this accuracy of this attribute is limited about
what data dh_assistant can read out from the following
command:
LC_ALL=C make -Rrnpsf debian/rules debhelper-fail-me 2>/dev/null
This command accepts no options or arguments.
detect-unknown-hook-targets (EXEC, AJSON, LINT)
Synopsis: dh_assistant detect-unknown-hook-targets
[--output-format=json] [command-options]
Detects unknown and possibly misspelled override targets and hook
targets in debian/rules that will most likely not be used by
dh(1).
**UNSAFE**: This command relies on the output of make. Even it
its dry-run mode, make may execute commands from debian/rules.
Avoid using on packages from untrusted sources, where you have
not reviewed the packaging for backdoors.
This command differs from detect-hook-targets subtly in the
scope. The detect-hook-targets will list all targets that looks
like hook targets whether they are applicable or not. This
command show all hook targets, for which a command cannot be
found in any sequence. Accordingly, this command is better for
linting purposes whereas detect-hook-targets is better if you
want to know which hook targets are present. All the limitations
listed in detect-hook-targets about scanning the rules file apply
equally to this command.
This command will attempt will attempt to load any sequence add-
on listed via build-dependencies and therefore these must be
installed. Additional modules can be passed via --with like with
dh(1) as needed.
This command will also need one of the following perl modules to
be available: Text::Levenshtein, Text::LevenshteinXS,
Text::Levenshtein::XS. The first one can be installed via apt
install libtext-levenshtein-perl.
The text output is intended for human consumption and should be
self-explanatory. Since it is not stable, it will not be
documented. The JSON output looks something like this:
{
"unknown-hook-targets": [
{
"target-name": "execute_before_dh_instlal",
"filename": "debian/rules",
"candidates": [
"execute_before_dh_install"
]
}
]
}
In more details:
unknown-hook-targets
List of all the unknown hook targets found along with
additional information about them.
target-name
The actual target name detected in the file (usually
debian/rules).
filename
This attribute reports which file the target was found
it. In most cases, this will always be "debian/rules"
though in case of include files, the target could appear
in an include file. Note this attribute is not super
reliable as make(1) only reports it for targets with a
"recipe" (targets with commands inside them). When make
does not provide the filename, dh_assistant blindly
assumes the filename is "debian/rules" (as overrides via
includes is not a commonly used feature).
Note this accuracy of this attribute is limited about
what data dh_assistant can read out from the following
command:
LC_ALL=C make -Rrnpsf debian/rules debhelper-fail-me 2>/dev/null
candidates
When not null and not empty, each element in this list
are names for likely candidates for the "correct" name of
this target.
filename
issues
If present, then it is a list of one or more reasons why this
output is definitely incomplete. Each element in the list is
an object with the following keys:
issue
A key defining the issue. Currently, it is always load-
addon, which signals that dh_assistant could not load the
add-on listed in the addon key.
Parsers should assume new issue types may appear in the
future.
addon
If present, it defines the name of a dh sequence add-on
that is related to the failure.
This command accepts the following options:
--output-format=FORMAT
Request a certain type of output format. Valid values are
text or json.
The text format is intended for human consumption and may
change between versions without any regard for machine
consumption. If you want to use this command for machine
consumption, please use the JSON format.
--no-linter-exit-code, --linter-exit-code
These options control whether the command should exit with
the linter exit code (2) or not (0) when an unknown target is
found. By default, it uses the linter exit code when an
unknown target is found.
--with addon, --without addon
These options behave the same as the dh(1) options with the
same name.
list-commands (RJSON)
Synopsis: dh_assistant list-commands [--output-format=json]
[command-options]
Load all dh sequence add-ons and extract a full list of all
commands that will be invoked across all sequences. The command
makes no attempt to filter out commands that will not be run due
to override targets or due to certain sequences not being run (by
dh or at all).
As the command will attempt to load all plugins, they must be
installed.
The text output is intended for human consumption and should be
self-explanatory. Since it is not stable, it will not be
documented. The JSON output looks something like this:
{
"commands": [
{
"command": "dh_auto_build"
},
{
"command": "dh_auto_clean"
},
[... more commands listed here... ]
],
"issues": [
{
"issue": "load-addon",
"addon": "foo"
}
]
}
commands
The top level key containing the list of all commands. Each
element in the list are an object and can have the following
keys:
command
The name of the command.
While most commands are resolved via PATH, a sequence
add-on could register a command via a full path (by
passing the path search). If so, the command provided in
this output will also use the full path.
issues
If present, then it is a list of one or more reasons why this
output is definitely incomplete. Each element in the list is
an object with the following keys:
issue
A key defining the issue. Currently, it is always load-
addon, which signals that dh_assistant could not load the
add-on listed in the addon key.
Parsers should assume new issue types may appear in the
future.
addon
If present, it defines the name of a dh sequence add-on
that is related to the failure.
This command accepts the following options:
--output-format=FORMAT
Request a certain type of output format. Valid values are
text or json.
The text format is intended for human consumption and may
change between versions without any regard for machine
consumption. If you want to use this command for machine
consumption, please use the JSON format.
--with addon, --without addon
These options behave the same as the dh(1) options with the
same name.
list-guessed-dh-config-files (AJSON)
Synopsis: dh_assistant list-guessed-dh-config-files
[command-options]
Load all dh sequence add-ons, determine the full list of commands
could be used by this source package and for each command used,
then attempt to guess which "config files" these commands are
interested in.
Note this command only guesses "per command config files".
Standard global config files such as debian/control,
debian/rules, and debian/compat are not included in this output.
As the command name implies, the resulting output is not a full
list (and will never be). The dh_assistant tool have to derive
this from optional metadata that commands can choose to provide
and dh_assistant has no means to validate that this metadata is
up to date.
As the command will attempt to load all plugins, they must be
installed.
The text output is intended for human consumption and should be
self-explanatory. Since it is not stable, it will not be
documented. The JSON output looks something like this:
{
"config-files": [
{
"commands": [
{
"command": "dh_autoreconf_clean"
}
],
"file-type": "pkgfile",
"pkgfile": "autoreconf.before"
},
{
"commands": [
{
"command": "dh_installgsettings"
}
],
"file-type": "pkgfile",
"pkgfile": "gsettings-override"
},
# [ ... more entries here ...]
],
"issues": [
{
"issue": "load-addon",
"addon": "foo"
}
]
}
config-files
The top level key containing the list of all config-files.
Each element in the list are an object and can have the
following keys:
file-type
The type of config file detected. At the time of writing,
this will always be pkgfile. However, other values may
appear in the future.
The pkgfile key means that the config file is a debhelper
pkgfile (named after the pkgfile sub in
Debian::Debhelper::Dh_Lib that locates the file).
pkgfile
When file-type is pkgfile, this key defines the name stem
of the pkgfile. An example, this will be install for
dh_install(1)'s config file and docs for
dh_installdocs(1)'s config file.
When file-type is not pkgfile, then this key will be
absent.
Typically names for these files are:
debian/PKGFILE
debian/PACKAGE.PKGFILE
However, there are more variants caused by --name plus
architecture specific suffixes.
internal
This key may exist and any value for it is not
standardized. Use at own peril.
It used for document certain specific implementation
details such as bug compatibility and may change as the
situation changes.
commands
This key will be a list with each element in it being an
object with the following keys:
command
Name of the command that is interested in this config
file. Multiple commands can be interested in the same
config file. An example of this would be
dh_installinit, dh_installsystemd and
dh_installtmpfiles, which all reacts to (the now)
deprecated tmpfile pkgfile. In the particular case,
only one command reacts to the file for a given
compat level (but that information is not available
to dh_assistant and therefore is not available in
this output either).
issues
If present, then it is a list of one or more reasons why this
output is definitely incomplete. Each element in the list is
an object with the following keys:
issue
A key defining the issue. Currently, it is always load-
addon, which signals that dh_assistant could not load the
add-on listed in the addon key.
Parsers should assume new issue types may appear in the
future.
addon
If present, it defines the name of a dh sequence add-on
that is related to the failure.
This command accepts the following options:
--with addon, --without addon
These options behave the same as the dh(1) options with the
same name.
log-installed-files (BLD)
Synopsis: [1mdh_assistant log-installed-files -ppkg
[--on-behalf-of-cmd=dh_foo] path ...
Mark one or more paths as installed for a given package. This is
useful for telling dh_missing(1) that the paths have been
installed manually.
The --on-behalf-of-cmd option can be used by third-party tools to
have dh_assistant list them as the installer of the provided
paths. The convention is to use the basename of the tool itself
as its name (e.g. dh_install).
Please keep in mind that:
• No glob or substitution expansion is done by dh_assistant on
the provided paths. If you want to use globs, have the shell
perform the expansion first.
• Paths must be given as relative to the source root directory
(e.g., debian/tmp/...)
• You can provide a directory. If you do, the directory and
anything recursively below it will be considered as
installed. Note that it is fine to provide the directory
even if paths inside of it has been excluded as long as the
directory is fully "covered".
• Do not worry about providing the same filename twice in
different invocations to dh_assistant due to -arch / -indep
overrides. While it will be recorded multiple internally,
dh_missing(1) will deduplicate when it parses the records.
Note this command only marks paths as installed. It does not
actually install them - the caller should ensure that the paths
are in fact handled (or installed).
restore-file-on-clean (BLD)
Synopsis: dh_assistant restore-file-on-clean FILE ...
This command will take a backup of listed files and tell
dh_clean(1) to restore them when it runs.
Note that generally you do not need to restore modified files on
clean. Often you can get away with just removing them if they are
regenerated anyway (which is the most common case for files being
modified during builds). Use this command when something taints
a file and the build does not cope with the file being removed.
The file is stored in debian/.debhelper. If you remove this
directory manually without calling dh_clean(1) then your
dh_assistant provided backup is gone permanently and the restore
will never occur. At this point, only a version control system or
another backup can restore the files.
The command has the following limitations:
No thread-safety - concurrency will corrupt the restore
The command relies on updating an internal index and
concurrent writes will cause it to be corrupt.
While most dh_* commands does not use the underlying
function, any of them could do so. Avoid running another dh_*
command while dh_assistant processes this command (especially
running multiple concurrent instances of dh_assistant
restore-file-on-clean is asking for corruption!).
Files only, not directories nor symlinks to files
This command will only restore files; not directories or
symlinks to files. It will reject any non-files.
Additionally, if the directory containing the file is
removed, the restore will fail (as debhelper does not track
the directory, it cannot restore it reliably). If this
happens, you can do a mkdir to restore the directory and run
dh_clean(1) again to get the files back. After that, consider
what went wrong and whether you are using the correct
tool(s).
Strict file names
All filenames must be relative to the package root (without
using the ./ prefix). No hidden files (that is any file
starting with a period .) and no version control directories
(such as CVS). The checks are best effort.
These checks are here to ensure you do not accidentally trash
important data that would help you undo mistakes.
Heavy duty
The command takes a full copy of all files you pass it. This
is fine for a handful of small files, which is the intended
use-case. If you find yourself passing 10+ files or very
large files, you might be applying a sledgehammer where you
needed a different tool.
supports (CFFA)
Synopsis: dh_assistant supports COMMAND
This command is a scripting aid to programmatically determine
whether dh_assistant knows about a given subcommand. Pass the
name of a subcommand and this command will exit successfully if
the subcommand was known and unsuccessfully otherwise.
Most commands have one or more of the following "tags" associated
with them. Their meaning is defined here.
EXEC
This command will or may execute content from the package. Do
not run on untrusted packages.
Note: This tag only applies if the command will out of the
box be unsafe. As an example, commands that parse the output
of make is inherently unsafe, because it is trivial make to
have make run code even in --dry-run mode. As a counter
example, commands that only loads dh add-ons will be
considered safe, because PERL5LIB is assumed to be curated to
only include trusted plugins.
AJSON
The command always provides JSON output. See "JSON OUTPUT"
for details.
OJSON
The command *can* provide JSON output via
--output-format=json, but does not do so by default. See
"JSON OUTPUT" for details when using --output-format=json.
LINT
The command is or can be used for linting purposes. This
command will exit with code 2 when an important issue is
found. Be careful if the command is also tagged with EXEC.
When this happens, the command should only be used on trusted
content (see the EXEC tag for details).
Note that commands may have options that redefine what is
considered an "important" issue.
CRFA
Mnemonic "Can be Run From Anywhere"
Most commands must be run inside a source package root
directory (a directory containing debian/control) because
debhelper will need the package metadata to lookup the
information. Any command with this tag are exempt from this
requirement and is expected to work regardless of where they
are run.
BLD The command is intended to be used as a part of a package
build. It may leave artifacts behind that will need a
dh_clean(1) invocation to remove.
Most commands uses JSON format as output. Consumers need to be
aware that:
• Additional keys may be added at any time. For backwards
compatibility, the absence of a key should in general be
interpreted as null unless another default is documented or
would be "obvious" for that case.
• Many keys can be null/undefined in special cases. As an
example, some information may be unavailable when this
command is run directly from the debhelper source (git
repository).
The output will be prettified when stdout is detected as a
terminal. If you need to pipe the output to a pager/file (etc.)
and still want it prettified, please use an external JSON
formatter. An example of this:
dh_assistant supported-compat-levels | json_pp | less
debhelper(7)
This program is a part of debhelper.
This page is part of the debhelper (helper programs for
debian/rules) project. Information about the project can be
found at [unknown -- if you know, please contact man-
[email protected]] If you have a bug report for this manual page,
send it to [email protected]. This page was obtained from
the project's upstream Git repository
⟨https://salsa.debian.org/debian/debhelper.git⟩ on 2024-06-14.
(At that time, the date of the most recent commit that was found
in the repository was 2024-06-09.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
13.15.3 2024-06-13 DH_ASSISTANT(1)
Pages that refer to this page: dh(1), debhelper(7)
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