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.