File: FAQ

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debdelta 0.19
  • links: PTS
  • area: main
  • in suites: etch, etch-m68k
  • size: 436 kB
  • ctags: 172
  • sloc: python: 2,309; ansic: 188; sh: 117; makefile: 52; awk: 21
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Q: How do I use it?

A: Quick answer:
  apt-get update
  su nobody -c debdelta-upgrade
  mv /tmp/archives/*deb  /var/cache/apt/archives
  apt-get upgrade



Q: Do you use 'xdelta' or 'bsdiff' ? bsdiff is better, but
   bsdiff is quite memory-hungry. It requires max(17*n,9*n+m)+O(1)
   bytes of memory, where n is the size of the old file and m is the
   size of the new file. bspatch requires n+m+O(1) bytes.

A: 'debdelta' has an option '-M ' to choose between 'xdelta' and 'bsdiff' ;
 by default, it uses 'xdelta' when memory usage would exceed 50Mb 

 (Ah so max(17*n,9*n+m) is the correct formula! The man page just says
 '17*n'.  But in my stats, that that is not the case; my stats are
 estimating that the memory is '12*n' so that is what I use. )



Q: How do you integrate this approach with the minimal security
  that signed Release files give us today?

A: 'debpatch' recreates the new .deb , and guarantees that it is equal to the
  one in archives, so archive signatures can be verified
 ( for this reason, 'debdelta'  does not use dpkg-repack )



Q: What about the kind of signatures dpkg-sig provides?

A: Supported.



Q: What about .debs where the data part is compressed with bzip ?

A: currently, is unsupported (I never found one :-)
  but I did write some code to support it.



Q: can 'debpatch' recreate the new .deb using the installed old .deb, even when
   there are dpkg-diversions ?

A:  yes.



Q: can 'debpatch' recreate the new .deb using the installed old .deb, even when
   conf files where modified ?

A:  yes.



Q: can 'debpatch' recreate the new .deb using the installed old .deb, 
  when 'prelink' is used in the host?

A: currently, no.