Download packages via apt without root privlidges

If you install the grep-dctrl package, you can use grep-available:

grep-available -F Provides -s Package <virtual-package-name>

I don't have hadoop packages available in my debian sources.list so i'll use mail-transport-agent as an example:

$ grep-available -F Provides -s Package  mail-transport-agent
Package: xmail
Package: exim4-daemon-light
Package: exim4-daemon-heavy
Package: esmtp-run
Package: postfix
[...most deleted...]

if you want version numbers too:

$ grep-available -F Provides -s Package,Version  mail-transport-agent
Package: xmail
Version: 1.27-1.1+b1

Package: exim4-daemon-light
Version: 4.76-2

Package: exim4-daemon-heavy
Version: 4.76-2

Package: esmtp-run
Version: 1.2-6
[...]

Note the convenient, easily parsed paragraph mode for each package in this second example.

There are numerous other options, including omitting the field names ("Package:", "Version:", etc). See the man page or --help for more details.

Yeah, one would think that this was about the dpkg --admindir option, but in this case it turns out that apt-get is deriving the AdminDir from the Dir::State::status value. I ended up downloading the source code for apt, and found the following snippet in ./apt-pkg/deb/debsystem.cc.

// Create the lockfile
string AdminDir = flNotFile(_config->Find("Dir::State::status"));
d->LockFD = GetLock(AdminDir + "lock");
if (d->LockFD == -1)
{
   if (errno == EACCES || errno == EAGAIN)
      return _error->Error(_("Unable to lock the administration directory (%s), "
                             "is another process using it?"),AdminDir.c_str());
   else
      return _error->Error(_("Unable to lock the administration directory (%s), "
                             "are you root?"),AdminDir.c_str());
}

So for the purpose of this exercise setting Dir::State::status to /foo/bar/status will translate into the AdminDir /foo/bar and the lock file /foo/bar/lock.

I haven't investigated this further, but for me apt-get assumed that the status file already existed. Creating an empty file using touch worked well enough to at least not make apt-get complain.