dpkg-shlibdeps(1)                                 dpkg suite                                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 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
              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
              /var/lib/dpkg.

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

       --version
              Show the version and exit.

ENVIRONMENT
       DPKG_COLORS
              Sets  the  color  mode (since dpkg 1.18.5).  The currently accepted values are: auto (default),
              always and never.

       DPKG_NLS
              If set, it will be used to decide whether to activate Native Language Support,  also  known  as
              internationalization  (or  i18n) support (since dpkg 1.19.0).  The accepted values are: 0 and 1
              (default).

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 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
              /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).

1.19.7                                            2019-06-03                                dpkg-shlibdeps(1)

Usage: dpkg-shlibdeps [<option>...] <executable>|-e<executable> [<option>...]

Positional options (order is significant):
  <executable>             include dependencies for <executable>,
  -e<executable>           (use -e if <executable> starts with '-')
  -d<dependency-field>     next executable(s) set shlibs:<dependency-field>.

Options:
  -l<library-dir>          add directory to private shared library search list.
  -p<varname-prefix>       set <varname-prefix>:* instead of shlibs:*.
  -O[<file>]               write variable settings to stdout (or <file>).
  -L<local-shlibs-file>    shlibs override file, not debian/shlibs.local.
  -T<substvars-file>       update variables here, not debian/substvars.
  -t<type>                 set package type (default is deb).
  -x<package>              exclude package from the generated dependencies.
  -S<package-build-dir>    search needed libraries in the given
                             package build directory first.
  -I<package-build-dir>    ignore needed libraries, shlibs and symbols files
                             in the given build directory.
  -v                       enable verbose mode (can be used multiple times).
  --ignore-missing-info    don't fail if dependency information can't be found.
  --warnings=<value>       define set of active warnings (see manual page).
  --admindir=<directory>   change the administrative directory.
  -?, --help               show this help message.
      --version            show the version.

Dependency fields recognized are:
  Suggests/Recommends/Depends/Pre-Depends