NAME | SYNOPSIS | DESCRIPTION | OPTIONS | DIAGNOSTICS | SEE ALSO | COLOPHON

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):

       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 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).

OPTIONS         top

       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.

DIAGNOSTICS         top

   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.

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
       ⟨git://git.debian.org/git/dpkg/dpkg.git⟩ on 2017-11-25.  (At that
       time, the date of the most recent commit that was found in the repos‐
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1.18.15-3-ga2ef                  1970-01-01                dpkg-shlibdeps(1)

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