debdeltas(1) compute deltas between Debian packages


debdeltas [OPTION]... ARGS ...


debdeltas computes deltas between the old and new versions of Debian packages.

The explanation of what a delta is is in debdelta(1).


In all of the following, ARGS can be, a Debian binary file (usually, a file ending in .deb), or a directory containing such files, or a Packages file (that is, an index file such as those found in Debian mirrors - even the zipped ones - see apt-ftparchive(1) ). We will call cmdline all such args that are not related to an option.

As a first step, debdeltas builds an internal list of Debian packages. To this end, it parses all ARGS of the options --alt , --old , and those ARGS given as non-option arguments (the aforementioned cmdline args). If the argument is a Debian package, debdeltas adds it to the list; if the argument is a directory, debdeltas scans it for Debian packages to be added to the list; if the argument is Packages files, debdeltas parses it and adds all Debian packages to the list.

Then debdeltas groups all found Debian packages by name and architecture.

For each group, the newest cmdline version is isolated, and then deltas are computed from all --old versions to that version.

These deltas are stored in many delta files with appropriate names of the form name_oldversion_newversion_architecture.debdelta ; the location of the delta files is specified by the "--dir" option.

Note that the location of files in a Packages index is specified relative to the base of the mirror, e.g. Filename: pool/main/x/xxx/xxx_3_i386.deb For this reason, any Packages argument must presented with a long path (that contains at least the dists directory).

Note also that the same directory or index can be provided many times, as --old, as --alt, and as cmdline argument.

Note also that debdeltas will skip all packages that are smaller than 10KB.


--dir DIR
force saving of deltas in this DIR (otherwise they go in the dir of the newer deb_file).
--alt ARGS
this is parsed as the non-option command line, but the found packages are never considered for a delta. They are considered though when --clean-deltas is used, to decide if to delete a delta; and are useful to find debs that are deleted from indexes and moved elsewhere. Multiple --alt can be specified.
--old ARGS
this is parsed as the non-option command line, and the found packages are considered as the older versions. Multiple --old can be specified. Moreover, when scanning a Packages index, it is not an error if files do not exist, as long as they have been moved in a --alt directory. Note that, if no --old is specified, then no deltas will be generated.
--forensicdir DIR
write hashes files; these are to be compared with those produced by debdelta-upgrade --forensic=...
when a delta fails

The double slash

If a directory path is provided as argument to --dir, and it ends in // , then this triggers a specific behaviour related to files found in Packages indexes (as presented in the commandline). If a package in a index is stored in pool/main/x/xxx/xxx_3_i386.deb , and --dir is /tmp/foobar// , then the delta will be saved in /tmp/foobar/pool/main/x/xxx/xxx_2_3_i386.debdelta. The same is true for --alt (and is useful to find old versions of a package).


--signing-key KEY
key used to sign the deltas (using GnuPG)
-n N
how many deltas to produce at maximum for each unique package/arch (default unlimited)
delete deltas that upgrade to packages versions that are not found in the cmdline ARGS, and are at least two days old (according to mtime).
do not include MD5 info in debdelta.
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').
check that the patch does apply.
verbose (can be added multiple times).
print traceback on 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).

keep temporary files (use for debugging).
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.
Just list the deltas that would be created.


See debdelta(1)


See debdelta(1)


debdeltas --dir /tmp/ --old ~/mydebs ~/mydebs will generate all deltas to upgrade from the old versions in ~/mydebs to the newest version in ~/mydebs , and store the deltas in /tmp/

debdeltas --dir /tmp// --old /mirror/debian/dists/lenny/main/binary-i386/Packages.gz /mirror/debian/dists/squeeze/main/binary-i386/Packages.gz will generate all deltas to upgrade main/i386 from lenny to squeeze, and store the deltas in a pool structure under /tmp/

See also the example scripts /usr/share/debdelta/debmirror-delta-security and /usr/share/debdelta/debmirror-deltas


Report bugs to <[email protected]>.


Debdelta was written and is copyright © 2006-09 Andrea Mennucci.
This man page was written by Jegou Pierre-yves <[email protected]>.


This is free software. You may redistribute copies of it under the terms of the GNU Library General Public License <>. There is NO WARRANTY, to the extent permitted by law.