download currently installed Debian package without reinstalling

Sometimes it’s necessary to download a Debian package from a repository without actually intsalling or reinstalling it.

# apt-get -d --reinstall -o=dir::cache=/tmp install rssh
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Suggested packages:
  cvs rdist subversion makejail
The following NEW packages will be installed:
0 upgraded, 1 newly installed, 0 to remove and 102 not upgraded.
Need to get 59.4 kB of archives.
After this operation, 225 kB of additional disk space will be used.
Get:1 squeeze/main rssh i386 2.3.2-13squeeze3 [59.4 kB]
Fetched 59.4 kB in 0s (178 kB/s)
Download complete and in download only mode

This downloaded the rssh .deb package to /tmp/archives without reinstalling over the existing version.

# ls -l /tmp/archives
total 64
-rw-r----- 1 root root     0 Jun  5 09:05 lock
drwxr-xr-x 2 root root  4096 Jun  5 09:05 partial
-rw-r--r-- 1 root root 59428 Nov 27  2012 rssh_2.3.2-13squeeze3_i386.deb