Ubuntu – dpkg or apt-get which of the two gives a more complete result

Both answers already provided have their pros and cons.

Starting with debfoster gives a list of packages which is simple to parse, so the following gives the requested result:

apt-cache policy $(debfoster -q -d tcpdump|tail -n +2)|awk '/^[^ ]/ { package=$0 } /  Installed/ { print package " " $2 }'

using tail to skip the first line and awk to process the result in a single operation. (Using a command substitution avoids the need to process newlines.) Starting with debfoster means we can only do this with a package which is already installed, so we can then use dpkg to provide more information:

dpkg -l $(debfoster -q -d tcpdump|tail -n +2)

Starting with apt-rdepends gives a list of packages which is a little harder to process, with duplicates; but it has the advantage of being able to process packages which aren't yet installed:

apt-cache policy $(apt-rdepends -p tcpdump 2>| /dev/null|awk '/Depends/ {print $2}'|sort -u)|awk '/^[^ ]/ { package=$0 } /  Installed/ { print package " " $2 }'

This can also be used with dpkg -l:

dpkg -l $(apt-rdepends -p tcpdump 2>| /dev/null|awk '/Depends/ {print $2}'|sort -u)

but this requires that dpkg know about all the packages involved, which may not be the case if the package being processed isn't installed.

debfoster includes Recommends by default; this can be disabled using --option UseRecommends=no:

debfoster -q --option UseRecommends=no -d tcpdump

apt-rdepends doesn't include Recommends by default; this can be enabled using -f Depends,PreDepends,Recommends -s Depends,PreDepends,Recommends:

apt-rdepends -f Depends,PreDepends,Recommends -s Depends,PreDepends,Recommends -p tcpdump

although it doesn't give all the dependencies debfoster finds in that case. (For example debfoster finds that tcpdump depends on apt via libssl1.0.0, debconf and apt-utils, but apt-rdepends doesn't.)

A slight variation on Installing packages by importing the list with dpkg --set-selections should do the trick.

Save the list of packages on your reference system:

dpkg --get-selections > packages.lst

Then install packages based on that list on your target system, after updating the list of available packages:

dpkg --merge-avail <(apt-cache dumpavail)
dpkg --clear-selections
dpkg --set-selections < packages.lst
apt-get dselect-upgrade