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Re: ITP: libsafe (again, and need a sponsor...)

On Jun 14, Ron Rademaker wrote:
> So, that means I can use a perl script (not using any perl-modules) in
> postinst, right???

Yes.  You can use any script you want in your postinst, as long as
your package depends (not predepends) on that interpreter.  (dpkg
guarantees that your postinst won't be run until all of your package's
dependencies are satisfied.)  So technically you could use anything
you want in your postinst, as long as it Depends on the appropriate

Pre-Depends are only required for packages that have a non-sh preinst
and a few other weird situations, where the order of unpacking is
important (for example, libc6 predepends on a recent version of ldso,
because it would break horribly otherwise).  From the Debian FAQ:

7.10 What is meant by Pre-Depends? 

"Pre-Depends" is a special dependency. 

In the case of most packages, dpkg will unpack its archive file (i.e.,
its .deb file) independently of whether or not the files on which it
depends exist on the system. Simplistically, unpacking means that dpkg
will extract the files from the archive file that were meant to be
installed on your filesystem, and put them in place. If those packages
depend on the existence of some other packages on your system, dpkg
will refuse to complete the installation by executing its "configure"
action until the other packages are installed.

However, for some packages, dpkg will refuse even to unpack them until
certain dependencies are resolved. Such packages are said to
"Pre-depend" on the presence of some other packages. The Debian
project provided this mechanism to support the safe upgrading of
systems from a.out format to ELF format, where the order in which
packages were unpacked was critical. 

More detailed information on the use of these terms can be found in
the Debian programmer's manual. 


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