apt-get

• man apt-get

  apt-get install python-opencv  #安装python-opencv
  apt-get remove  python-opencv  #卸载python-opencv
  apt-get update                 #从/etc/apt/sources.list 更新apt-cache
  apt-get upgrade                #从/etc/apt/sources.list 更新apt-cache，同时cache更新软件

• man apt-cache

  /var/lib/apt/lists/mirrors.tuna.tsinghua.edu.cn_debian_dists_jessie_main_binary-arm64_Packages
  apt-cache showpkg python-opencv
  apt-cache show python-pencv

• man sources.list

  EXAMPLES
       Uses the archive stored locally (or NFS mounted) at /home/jason/debian for stable/main, stable/contrib, and stable/non-free.
  
           deb file:/home/jason/debian stable main contrib non-free
  
       As above, except this uses the unstable (development) distribution.
  
           deb file:/home/jason/debian unstable main contrib non-free
  
       Source line for the above
  
           deb-src file:/home/jason/debian unstable main contrib non-free
  
       The first line gets package information for the architectures in APT::Architectures while the second always retrieves amd64 and armel.
  
           deb http://ftp.debian.org/debian jessie main
           deb [ arch=amd64,armel ] http://ftp.debian.org/debian jessie main
  
       Uses HTTP to access the archive at archive.debian.org, and uses only the hamm/main area.
  
           deb http://archive.debian.org/debian-archive hamm main
  
       Uses FTP to access the archive at ftp.debian.org, under the debian directory, and uses only the jessie/contrib area.
  
           deb ftp://ftp.debian.org/debian jessie contrib
  
       Uses FTP to access the archive at ftp.debian.org, under the debian directory, and uses only the unstable/contrib area. If this line appears as well as the one in the previous example in
       sources.list a single FTP session will be used for both resource lines.
  
           deb ftp://ftp.debian.org/debian unstable contrib
  
       Uses HTTP to access the archive at ftp.tlh.debian.org, under the universe directory, and uses only files found under unstable/binary-i386 on i386 machines, unstable/binary-amd64 on amd64, and so
       forth for other supported architectures. [Note this example only illustrates how to use the substitution variable; official debian archives are not structured like this]
  
           deb http://ftp.tlh.debian.org/universe unstable/binary-$(ARCH)/
  

• https://wiki.debian.org/DebianExperimental