DEBDELTAS(1)

✨ debdeltas — the manual, but make it cute ✨

okay so bestie, this is the manual page for debdeltas, a User Command from the DEBDELTAS(1) page. it computes deltas between Debian packages and it is honestly kind of iconic. let's get into it 🫶

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🌸 NAME 🌸

debdeltas — compute deltas between Debian packages. that's it, that's the vibe. 💅

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🎀 SYNOPSIS 🎀

debdeltas [OPTION]... ARGS ...

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🦋 DESCRIPTION 🦋

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

and if you're sitting there like "bestie what even is a delta" — the full explanation lives in debdelta(1). go read that one, iykyk. 💜

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👑 COMMAND ARGUMENTS 👑

okay so, in all of the following, ARGS can be any of these three things:

• a Debian binary file (usually, a file ending in .deb) 💖
• a directory containing such files 📁
• a Packages file (that is, an index file such as those found in Debian mirrors — even the zipped ones — see apt-ftparchive(1))

we're gonna call cmdline all such args that are not related to an option. no cap.

as a first step, debdeltas builds an internal list of Debian packages. to do this, it parses all ARGS of the options --alt, --old, and those ARGS given as non-option arguments (the aforementioned cmdline args). and then:

• 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. slay.

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 be presented with a long path (that contains at least the dists directory). don't be lazy about it bestie 😭

note also that the same directory or index can be provided many times — as --old, as --alt, and as a cmdline argument. it's giving "no thoughts, head empty, just parse it again" 🙈

note also that debdeltas will skip all packages that are smaller than 10KB. tiny babies don't get deltas. 💀

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💖 MAIN OPTIONS 💖

• --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 they're 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 😭 (yes really, zero, nada).
• --forensicdir DIR — write hashes files; these are to be compared with those produced by debdelta-upgrade --forensic=... when a delta fails. 🔍

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🌈 The double slash 🌈

okay this one is lowkey my favorite. listen up. 👑

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). so if a package in an 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). the double slash is doing the most and we love her for it 💅✨

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⭐ OTHER OPTIONS ⭐

• --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). 🔥
• --clean-deltas — 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). 🧹
• --no-md5 — do not include MD5 info in debdelta. 🙅
• --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'). 🧠
• --test — check that the patch does apply. ✅
• -v — verbose (can be added multiple times). 🗣️
• -d — 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). 💀

• -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. 🚫
• --no-act — just list the deltas that would be created. 👻

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🔒 SECURITY 🔒

see debdelta(1). (yes, we're outsourcing that one. go look bestie 🫶)

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🚦 EXIT STATUS 🚦

see debdelta(1). (also outsourcing, sorry not sorry 💅)

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🌟 EXAMPLES 🌟

this one generates all deltas to upgrade from the old versions in ~/mydebs to the newest version in ~/mydebs, and stores the deltas in /tmp/:

debdeltas --dir /tmp/ --old ~/mydebs ~/mydebs

and this one generates all deltas to upgrade main/i386 from lenny to squeeze, and stores the deltas in a pool structure under /tmp/:

debdeltas --dir /tmp// --old /mirror/debian/dists/lenny/main/binary-i386/Packages.gz /mirror/debian/dists/squeeze/main/binary-i386/Packages.gz

see also the example scripts /usr/share/debdelta/debmirror-delta-security and /usr/share/debdelta/debmirror-deltas — they're giving main character energy fr fr ✨

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😭 REPORTING BUGS 😭

report bugs to <mennucc1@debian.org>. be nice, they're doing their best 🫶

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👑 AUTHORS 👑

Debdelta was written and is copyright © 2006-09 Andrea Mennucci.

This man page was written by Jegou Pierre-yves <pierreyves.jeg@voila.fr>.

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💜 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.

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🦋 SEE ALSO 🦋

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

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okay and that's the whole page bestie!! this was debdeltas from the DEBDELTAS(1) manual, version dated aug 2009, and the footer said debdeltas — yeah, that's right, she named herself twice, iconic behavior. now go compute some deltas. mwah 💅💖✨