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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | ENVIRONMENT | DIAGNOSTICS | SEE ALSO | COLOPHON |
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dpkg-shlibdeps(1) dpkg suite dpkg-shlibdeps(1)
dpkg-shlibdeps - generate shared library substvar dependencies
dpkg-shlibdeps [option...] [-e] executable [option...]
dpkg-shlibdeps calculates shared library dependencies for
executables named in its arguments. The dependencies are added
to the substitution variables file debian/substvars as variable
names shlibs:dependency-field where dependency-field is a
dependency field name. Any other variables starting with shlibs:
are removed from the file.
dpkg-shlibdeps has two possible sources of information to
generate dependency information. Either symbols files or shlibs
files. For each binary that dpkg-shlibdeps analyzes, it finds
out the list of libraries that it's linked with. Then, for each
library, it looks up either the symbols file, or the shlibs file
(if the former doesn't exist or if debian/shlibs.local contains
the relevant dependency). Both files are supposed to be provided
by the library package and should thus be available as
/usr/local/var/lib/dpkg/info/package.symbols or
/usr/local/var/lib/dpkg/info/package.shlibs. The package name is
identified in two steps: find the library file on the system
(looking in the same directories that ld.so would use), then use
dpkg -S library-file to lookup the package providing the library.
Symbols files
Symbols files contain finer-grained dependency information by
providing the minimum dependency for each symbol that the library
exports. The script tries to find a symbols file associated to a
library package in the following places (first match is used):
debian/*/DEBIAN/symbols
Shared library information generated by the current build
process that also invoked dpkg-shlibdeps. They are generated
by dpkg-gensymbols(1). They are only used if the library is
found in a package's build tree. The symbols file in that
build tree takes precedence over symbols files from other
binary packages.
/usr/local/etc/dpkg/symbols/package.symbols.arch
/usr/local/etc/dpkg/symbols/package.symbols
Per-system overriding shared library dependency information.
arch is the architecture of the current system (obtained by
dpkg-architecture -qDEB_HOST_ARCH).
Output from “dpkg-query --control-path package symbols”
Package-provided shared library dependency information.
Unless overridden by --admindir, those files are located in
/usr/local/var/lib/dpkg.
While scanning the symbols used by all binaries, dpkg-shlibdeps
remembers the (biggest) minimal version needed for each library.
At the end of the process, it is able to write out the minimal
dependency for every library used (provided that the information
of the symbols files are accurate).
As a safe-guard measure, a symbols file can provide a Build-
Depends-Package or Build-Depends-Packages meta-information field
and dpkg-shlibdeps will extract the minimal version required by
the corresponding package in the Build-Depends field and use this
version if it's higher than the minimal version computed by
scanning symbols.
Shlibs files
Shlibs files associate directly a library to a dependency
(without looking at the symbols). It's thus often stronger than
really needed but very safe and easy to handle.
The dependencies for a library are looked up in several places.
The first file providing information for the library of interest
is used:
debian/shlibs.local
Package-local overriding shared library dependency
information.
/usr/local/etc/dpkg/shlibs.override
Per-system overriding shared library dependency information.
debian/*/DEBIAN/shlibs
Shared library information generated by the current build
process that also invoked dpkg-shlibdeps. They are only used
if the library is found in a package's build tree. The
shlibs file in that build tree takes precedence over shlibs
files from other binary packages.
Output from “dpkg-query --control-path package shlibs”
Package-provided shared library dependency information.
Unless overridden by --admindir, those files are located in
/usr/local/var/lib/dpkg.
/usr/local/etc/dpkg/shlibs.default
Per-system default shared library dependency information.
The extracted dependencies are then directly used (except if they
are filtered out because they have been identified as duplicate,
or as weaker than another dependency).
dpkg-shlibdeps interprets non-option arguments as executable
names, just as if they'd been supplied as -eexecutable.
-eexecutable
Include dependencies appropriate for the shared libraries
required by executable. This option can be used multiple
times.
-ldirectory
Prepend directory to the list of directories to search for
private shared libraries (since dpkg 1.17.0). This option
can be used multiple times.
Note: Use this option instead of setting LD_LIBRARY_PATH, as
that environment variable is used to control the run-time
linker and abusing it to set the shared library paths at
build-time can be problematic when cross-compiling for
example.
-ddependency-field
Add dependencies to be added to the control file dependency
field dependency-field. (The dependencies for this field are
placed in the variable shlibs:dependency-field.)
The -ddependency-field option takes effect for all
executables after the option, until the next -ddependency-
field. The default dependency-field is Depends.
If the same dependency entry (or set of alternatives) appears
in more than one of the recognized dependency field names
Pre-Depends, Depends, Recommends, Enhances or Suggests then
dpkg-shlibdeps will automatically remove the dependency from
all fields except the one representing the most important
dependencies.
-pvarname-prefix
Start substitution variables with varname-prefix: instead of
shlibs:. Likewise, any existing substitution variables
starting with varname-prefix: (rather than shlibs:) are
removed from the substitution variables file.
-O[filename]
Print substitution variable settings to standard output (or
filename if specified, since dpkg 1.17.2), rather than being
added to the substitution variables file (debian/substvars by
default).
-ttype
Prefer shared library dependency information tagged for the
given package type. If no tagged information is available,
falls back to untagged information. The default package type
is deb. Shared library dependency information is tagged for
a given type by prefixing it with the name of the type, a
colon, and whitespace.
-Llocal-shlibs-file
Read overriding shared library dependency information from
local-shlibs-file instead of debian/shlibs.local.
-Tsubstvars-file
Write substitution variables in substvars-file; the default
is debian/substvars.
-v Enable verbose mode (since dpkg 1.14.8). Numerous messages
are displayed to explain what dpkg-shlibdeps does.
-xpackage
Exclude the package from the generated dependencies (since
dpkg 1.14.8). This is useful to avoid self-dependencies for
packages which provide ELF binaries (executables or library
plugins) using a library contained in the same package. This
option can be used multiple times to exclude several
packages.
-Spackage-build-dir
Look into package-build-dir first when trying to find a
library (since dpkg 1.14.15). This is useful when the source
package builds multiple flavors of the same library and you
want to ensure that you get the dependency from a given
binary package. You can use this option multiple times:
directories will be tried in the same order before
directories of other binary packages.
-Ipackage-build-dir
Ignore package-build-dir when looking for shlibs, symbols,
and shared library files (since dpkg 1.18.5). You can use
this option multiple times.
--ignore-missing-info
Do not fail if dependency information can't be found for a
shared library (since dpkg 1.14.8). Usage of this option is
discouraged, all libraries should provide dependency
information (either with shlibs files, or with symbols files)
even if they are not yet used by other packages.
--warnings=value
value is a bit field defining the set of warnings that can be
emitted by dpkg-shlibdeps (since dpkg 1.14.17). Bit 0
(value=1) enables the warning “symbol sym used by binary
found in none of the libraries”, bit 1 (value=2) enables the
warning “package could avoid a useless dependency” and bit 2
(value=4) enables the warning “binary should not be linked
against library”. The default value is 3: the first two
warnings are active by default, the last one is not. Set
value to 7 if you want all warnings to be active.
--admindir=dir
Change the location of the dpkg database (since dpkg 1.14.0).
The default location is /usr/local/var/lib/dpkg.
-?, --help
Show the usage message and exit.
--version
Show the version and exit.
DEB_HOST_ARCH
Sets the host architecture. This affects the objects and
symbols files searched for and their default search
pathnames.
DPKG_COLORS
Sets the color mode (since dpkg 1.18.5). The currently
accepted values are: auto (default), always and never.
DPKG_NLS
If set, it will be used to decide whether to activate Native
Language Support, also known as internationalization (or
i18n) support (since dpkg 1.19.0). The accepted values are:
0 and 1 (default).
Warnings
Since dpkg-shlibdeps analyzes the set of symbols used by each
binary of the generated package, it is able to emit warnings in
several cases. They inform you of things that can be improved in
the package. In most cases, those improvements concern the
upstream sources directly. By order of decreasing importance,
here are the various warnings that you can encounter:
symbol sym used by binary found in none of the libraries.
The indicated symbol has not been found in the libraries
linked with the binary. The binary is most likely a library
and it needs to be linked with an additional library during
the build process (option -llibrary of the linker).
binary contains an unresolvable reference to symbol sym: it's
probably a plugin
The indicated symbol has not been found in the libraries
linked with the binary. The binary is most likely a plugin
and the symbol is probably provided by the program that loads
this plugin. In theory a plugin doesn't have any SONAME but
this binary does have one and as such it could not be clearly
identified as such. However the fact that the binary is
stored in a non-public directory is a strong indication
that's it's not a normal shared library. If the binary is
really a plugin, then disregard this warning. But there's
always the possibility that it's a real library and that
programs linking to it are using an RPATH so that the dynamic
loader finds it. In that case, the library is broken and
needs to be fixed.
package could avoid a useless dependency if binary was not linked
against library (it uses none of the library's symbols)
None of the binaries that are linked with library use any of
the symbols provided by the library. By fixing all the
binaries, you would avoid the dependency associated to this
library (unless the same dependency is also generated by
another library that is really used).
package could avoid a useless dependency if binaries were not
linked against library (they use none of the library's symbols)
Exactly the same as the above warning, but for multiple
binaries.
binary should not be linked against library (it uses none of the
library's symbols)
The binary is linked to a library that it doesn't need. It's
not a problem but some small performance improvements in
binary load time can be obtained by not linking this library
to this binary. This warning checks the same information as
the previous one but does it for each binary instead of doing
the check globally on all binaries analyzed.
Errors
dpkg-shlibdeps will fail if it can't find a public library used
by a binary or if this library has no associated dependency
information (either shlibs file or symbols file). A public
library has a SONAME and is versioned (libsomething.so.X). A
private library (like a plugin) should not have a SONAME and
doesn't need to be versioned.
couldn't find library library-soname needed by binary (its RPATH
is 'rpath')
The binary uses a library called library-soname but dpkg-
shlibdeps has been unable to find the library. dpkg-
shlibdeps creates a list of directories to check as
following: directories listed in the RPATH of the binary,
directories added by the -l option, directories listed in the
LD_LIBRARY_PATH environment variable, cross multiarch
directories (ex. /lib/arm64-linux-gnu,
/usr/lib/arm64-linux-gnu), standard public directories (/lib,
/usr/lib), directories listed in /etc/ld.so.conf, and
obsolete multilib directories (/lib32, /usr/lib32, /lib64,
/usr/lib64). Then it checks those directories in the
package's build tree of the binary being analyzed, in the
packages' build trees indicated with the -S command-line
option, in other packages' build trees that contains a
DEBIAN/shlibs or DEBIAN/symbols file and finally in the root
directory. If the library is not found in any of those
directories, then you get this error.
If the library not found is in a private directory of the
same package, then you want to add the directory with -l. If
it's in another binary package being built, you want to make
sure that the shlibs/symbols file of this package is already
created and that -l contains the appropriate directory if it
also is in a private directory.
no dependency information found for library-file (used by
binary).
The library needed by binary has been found by dpkg-shlibdeps
in library-file but dpkg-shlibdeps has been unable to find
any dependency information for that library. To find out the
dependency, it has tried to map the library to a Debian
package with the help of dpkg -S library-file. Then it
checked the corresponding shlibs and symbols files in
/usr/local/var/lib/dpkg/info/, and in the various package's
build trees (debian/*/DEBIAN/).
This failure can be caused by a bad or missing shlibs or
symbols file in the package of the library. It might also
happen if the library is built within the same source package
and if the shlibs files has not yet been created (in which
case you must fix debian/rules to create the shlibs before
calling dpkg-shlibdeps). Bad RPATH can also lead to the
library being found under a non-canonical name (example:
/usr/lib/openoffice.org/../lib/libssl.so.0.9.8 instead of
/usr/lib/libssl.so.0.9.8) that's not associated to any
package, dpkg-shlibdeps tries to work around this by trying
to fallback on a canonical name (using realpath(3)) but it
might not always work. It's always best to clean up the
RPATH of the binary to avoid problems.
Calling dpkg-shlibdeps in verbose mode (-v) will provide much
more information about where it tried to find the dependency
information. This might be useful if you don't understand
why it's giving you this error.
deb-substvars(5), deb-shlibs(5), deb-symbols(5),
dpkg-gensymbols(1).
This page is part of the dpkg (Debian Package Manager) project.
Information about the project can be found at
⟨https://wiki.debian.org/Teams/Dpkg/⟩. If you have a bug report
for this manual page, see
⟨http://bugs.debian.org/cgi-bin/pkgreport.cgi?src=dpkg⟩. This
page was obtained from the project's upstream Git repository ⟨git
clone https://git.dpkg.org/git/dpkg/dpkg.git⟩ on 2024-06-14. (At
that time, the date of the most recent commit that was found in
the repository was 2024-05-21.) 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]
1.22.6-77-g86fe7 2024-03-10 dpkg-shlibdeps(1)
Pages that refer to this page: dh_makeshlibs(1), dh_shlibdeps(1), dpkg-buildtree(1), dpkg-gensymbols(1), deb-shlibs(5), deb-src-rules(5), deb-src-symbols(5), deb-substvars(5), deb-symbols(5)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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