package management - Command-line equivalences of some tasks in Synaptic

I already use apt-get for most of my package management. Yet, there are times when I occasionally need to use Synaptic to do certain things. I would like to learn the equivalent commands for doing the following things in Synaptic:

• Check a package's dependencies / dependent packages. (This can be done in Synaptic by viewing the properties of a package).


• Browse available packages


• Search (in package names as well as the details/descriptions) for some key. (The search function at the top of synaptic)


• Check if a package is installed or not

Also, is there a way to find packages that are no longer necessary (e.g. a package no longer in use because I removed a dependency). I have a feeling my system is terribly bloated because I removed certain programs and not all the dependencies went with them.

• Check a package's dependencies / dependent packages. (This can be done in Synaptic by viewing the properties of a package):

  
  

  apt-cache depend 'package-name'
  apt-cache rdepend 'package-name'
  




• Browse available packages

  
  

  apt-cache pkgnames
  apt-cache search '.*'
  apt-cache show 'package-name'
  




• Search (in package names as well as the details/descriptions) for some key. (The search function at the top of synaptic)

  
  

  apt-cache search pattern
  apt-cache --names-only search pattern
  




• Check if a package is installed or not

  
  

  dpkg -l | grep package-name
  

The last one could not give the desired result, because when the terminal width is narrow the columns are truncated. Safer alternatives are

dpkg-query -Wf '${Package}\n' | grep pkg
dpkg --get-selections | grep pkg