NAME

       debdelta - compute changes between Debian packages

SYNOPSIS

       debdelta [OPTION]... FROMFILE TOFILE DELTA

DESCRIPTION

       This  program  computes  changes between Debian packages FROMFILE and TOFILE. These changes are stored in
       the file DELTA.  The DELTA file may later be used by the  "debpatch"  program  to  recreate  TOFILE  from
       FROMFILE.  In  a  sense, the pair of programs "debdelta"/"debpatch" operate on Debian packages similar to
       how the pair "diff"/"patch" operate on text files; indeed, the output of "debdelta" may be used to  store
       and  transmit only the changes between Debian packages; but, contrary to the "diff" output, the output of
       "debdelta" is not human readable, but rather it is intended to be as small as possible (to  optimize  for
       less disk usage and/or faster transmission).

OPTIONS

       --signing-key KEY
              key used to sign the delta (using GnuPG).

       --no-md5
              do not include MD5 info in delta.

       --needsold
              create a patch that can only be used if the old .deb is available.

       --delta-algo ALGO
              use a specific backend for computing binary diffs; possible values are: xdelta xdelta-bzip xdelta3
              bsdiff

       -M Mb  maximum memory  to use (for 'bsdiff' or 'xdelta').

       -v     verbose (can be added multiple times).

       -d     print full traceback on Python errors; save useful info in temporary files in case that a  backend
              crashes.

              (If  '-d'  is added multiple times, it also adds to the patches other extra debugging checks: only
              for advanced bug tracking).

       -k     keep temporary files (use for debugging).

       --gpg-home
              specify a different home for GnuPG, default for root is /etc/debdelta/gnupg while for other  users
              is unset. See --homedir in gpg(1) for details.

       --disable-feature FEATURE
              disable an internal feature. See the documentation in README.features.

EXAMPLE

       The command
       debdelta libglib_2.12_all.deb libglib_2.14_all.deb /tmp/glib.debdelta
       will express the difference between two versions of libglib in /tmp/glib.debdelta ; the command
       debpatch -A /tmp/glib.debdelta libglib_2.12_all.deb /tmp/glib.deb
       will create in /tmp/glib.deb a perfect copy of libglib_2.14_all.deb.

SECURITY

       A  Debian  package that is recreated using debpatch is byte-by-byte identical to the original one; so the
       cryptographic archive authentication support for APT (see apt-secure(8) ) may be used to assert  that  it
       can be trusted to be installed. Moreover, if  a GnuPG key is specified using --signing-key then the delta
       file itself is cryptograhically protected using GnuPG, MD5 and SHA1  (using  the  same  method  as  dpkg-
       sig(1)  ).   Note  that,  for  non-root  users,   the master debdelta keyring /usr/share/keyrings/debian-
       debdelta-archive-keyring.gpg is added to the list of keyrings for gnupg.

EXIT STATUS

       0      if OK,

       1      if there was a retriable problem (e.g., out-of-disk-space, or an auxiliary program such 'lzma'  is
              missing and the user is asked to install the package 'lzma'),

       2      if there was a non-retriable problem,

       3      if there was an error in a  command-line option, or in a configuration file,

       4      if there is an internal error, and

       5      if exited due to keyboard interrupt.

REPORTING BUGS

       Report bugs to <mennucc1@debian.org>.

AUTHORS

       Debdelta was written and is copyright © 2006-09 Andrea Mennucci.
       This man page was written by Jegou Pierre-yves  <pierreyves.jeg@voila.fr>.

COPYING

       This  is  free  software.   You  may redistribute copies of it under the terms of the GNU Library General
       Public  License  <http://www.gnu.org/licenses/lgpl-2.0.html>.   There  is  NO  WARRANTY,  to  the  extent
       permitted by law.

SEE ALSO

       debdelta-upgrade(1), debpatch(1), debdeltas(1), /usr/share/doc/debdelta/README.