dpkg-shlibdeps(1) — Linux manual page


dpkg-shlibdeps(1)              dpkg suite              dpkg-shlibdeps(1)

NAME         top

       dpkg-shlibdeps - generate shared library substvar dependencies

SYNOPSIS         top

       dpkg-shlibdeps [option...] [-e]executable [option...]

DESCRIPTION         top

       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):

              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.


              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 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:

              Package-local overriding shared library dependency

              Per-system overriding shared library dependency

              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.

              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).

OPTIONS         top

       dpkg-shlibdeps interprets non-option arguments as executable
       names, just as if they'd been supplied as -eexecutable.

              Include dependencies appropriate for the shared libraries
              required by executable.  This option can be used multiple

              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

              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-

              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.

              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.

              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.

              Read overriding shared library dependency information from
              local-shlibs-file instead of debian/shlibs.local.

              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

              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.

              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.

              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.

              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.

              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.

              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.

              Show the version and exit.

ENVIRONMENT         top

              Sets the color mode (since dpkg 1.18.5).  The currently
              accepted values are: auto (default), always and never.

              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).

DIAGNOSTICS         top

       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

       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

       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

       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
              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

              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.

SEE ALSO         top

       deb-shlibs(5), deb-symbols(5), dpkg-gensymbols(1).

COLOPHON         top

       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
       ⟨https://salsa.debian.org/dpkg-team/dpkg.git⟩ on 2021-08-27.  (At
       that time, the date of the most recent commit that was found in
       the repository was 2021-06-17.)  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

1.19.6-2-g6e42d5               2019-03-25              dpkg-shlibdeps(1)

Pages that refer to this page: dh_makeshlibs(1)dh_shlibdeps(1)dpkg-gensymbols(1)deb-shlibs(5)deb-src-rules(5)deb-substvars(5)deb-symbols(5)