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       dpkg-shlibdeps - generate shared library substvar dependencies


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


       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: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  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  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).

              Package-provided shared library dependency information.   Unless
              overridden, admindir is /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  information.

              Per-system overriding shared library dependency information.

              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.

              Package-provided  shared library dependency information.  Unless
              overridden, admindir is /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).


       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.

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

              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

              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

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

              Write substitution variables in substvarsfile;  the  default  is

       -v     Enable  verbose mode. Numerous messages are displayed to explain
              what dpkg-shlibdeps does.

              Exclude the package from the  generated  dependencies.  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 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.

              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.

              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.

              Change the location of the dpkg database. The  default  location
              is /var/lib/dpkg.

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

              Show the version and exit.


       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.

       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 associated 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 previous one
              but does it for each binary instead of doing the check  globally
              on all binaries analyzed.


       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 ( 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
              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/, 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  command-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 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/    instead     of
              /usr/lib/  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.


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


       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.