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dpkg-shlibdeps(1)                         dpkg utilities                        dpkg-shlibdeps(1)



NAME
       dpkg-shlibdeps - generate shared library substvar dependencies

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

DESCRIPTION
       dpkg-shlibdeps  calculates  shared library dependencies for executables named in its argu‐
       ments. 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  pro‐
       vided  by  the  library  package  and should thus be available as /var/lib/dpkg/info/pack‐
       age.symbols or /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 depen‐
       dency  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.

       /etc/dpkg/symbols/package.symbols.arch

       /etc/dpkg/symbols/package.symbols
              Per-system overriding shared library dependency information.  arch is the architec‐
              ture 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 /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-informa‐
       tion field and dpkg-shlibdeps will extract the minimal version required by the correspond‐
       ing package in the Build-Depends field and use this version if it's higher than the  mini‐
       mal version computed by scanning symbols.

   Shlibs files
       Shlibs  files  associate  directly  a library to a dependency (without looking at the sym‐
       bols). 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.

       /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 /var/lib/dpkg.

       /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
       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
              Add 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 vari‐
              able 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 the substitution variables file.

       -O[filename]
              Print substitution variable settings to standard output (or filename if specified),
              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. Numerous messages are displayed to explain what dpkg-shlibdeps
              does.

       -xpackage
              Exclude the package from the generated dependencies. This is useful to avoid  self-
              dependencies  for packages which provide ELF binaries (executables or library plug‐
              ins) using a library contained in the same package. This option can be used  multi‐
              ple times to exclude several packages.

       -Spackage-build-dir
              Look  into  package-build-dir  first  when trying to find a library. 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  directo‐
              ries of other binary packages.

       --ignore-missing-info
              Do  not  fail if dependency information can't be found for a shared library.  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.   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. The default location is /var/lib/dpkg.

       -?, --help
              Show the usage message and exit.

       --version
              Show the version and exit.

DIAGNOSTICS
   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 pro‐
              gram 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. How‐
              ever the fact that the binary is stored in a non-public directory is a strong indi‐
              cation  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  associ‐
              ated  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
       uses 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 than the pre‐
              vious 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 fol‐
              lowing: directories listed in the  RPATH  of  the  binary,  directories  listed  in
              /etc/ld.so.conf,  directories  added  by  the  -l option, directories listed in the
              LD_LIBRARY_PATH  environment  variable,  and  standard  public  directories  (/lib,
              /usr/lib, /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 direc‐
              tory.   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  cre‐
              ated  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 /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 pack‐
              age 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
       deb-shlibs(5), deb-symbols(5), dpkg-gensymbols(1).



Debian Project                              2013-09-06                          dpkg-shlibdeps(1)


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