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

NAME
       dpkg-shlibdeps - generate shared library substvar dependencies

SYNOPSIS
       dpkg-shlibdeps [options] executable|-eexecutable [options]

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:dependencyfield	where dependencyfield is a dependency field name.
       Any other variables starting 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.

       -ddependencyfield
	      Add  dependencies to be added to the control file dependency field dependencyfield.
	      (The dependencies for this field are  placed  in	the  variable  shlibs:dependency-
	      field.)

	      The  -ddependencyfield  option  takes  effect for all executables after the option,
	      until the next -ddependencyfield.  The default dependencyfield is Depends.

	      If the same dependency entry (or set of alternatives) appears in more than  one  of
	      the recognised 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.

       -pvarnameprefix
	      Start substitution variables with varnameprefix: instead of shlibs:.  Likewise, any
	      existing substitution variables starting with varnameprefix: (rather than  shlibs:)
	      are removed from the the substitution variables file.

       -O     Print substitution variable settings to standard output, 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.

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

       -Tsubstvarsfile
	      Write substitution variables in substvarsfile; 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.

       -Spkgbuilddir
	      Look into pkgbuilddir 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 directories 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 "dependency on
	      library could be avoided" and bit 2 (value=4) enables the warning "binary shouldn't
	      be linked with 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.

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

       --version
	      Show the version and exit.

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.

       dependency  on  library	could be avoided if binaries were not uselessly linked against it
       (they use none of its 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).

       binary shouldn't be linked with library (it uses none of its 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  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's build trees indicated  with  the  -S  com-
	      mand-line  option, in other packages's 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 to LD_LIBRARY_PATH. 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 LD_LIBRARY_PATH 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).

AUTHORS
       Copyright (C) 1995-1996 Ian Jackson
       Copyright (C) 2000 Wichert Akkerman
       Copyright (C) 2006 Frank Lichtenheld
       Copyright (C) 2007-2008 Raphael Hertzog

       This is free software; see the GNU General Public Licence version 2 or later  for  copying
       conditions. There is NO WARRANTY.

Debian Project				    2011-03-04				dpkg-shlibdeps(1)
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