Provided by: dpkg-dev_1.18.4ubuntu1_all bug

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
       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
       /var/lib/dpkg/info/package.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
       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.

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

       /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 /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.

       /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
              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 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.

       --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 /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
              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
       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
              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  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
              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 /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

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