====== نصب نرم‌افزار ======
  
  * /etc/apt/sources.list
        deb http://deb.debian.org/debian bullseye main contrib non-free
        deb http://deb.debian.org/debian bullseye-updates main contrib non-free
        deb http://deb.debian.org/debian bullseye-backports main contrib non-free
        deb http://security.debian.org/debian-security bullseye-security main contrib non-free
        deb-src http://deb.debian.org/debian bullseye main contrib non-free
        deb-src http://deb.debian.org/debian bullseye-updates main contrib non-free
        deb-src http://deb.debian.org/debian bullseye-backports main contrib non-free
        deb-src http://security.debian.org/debian-security bullseye-security main contrib non-free
  
  * apt update
  * apt upgrade
  * apt install tree
  * apt search speedometer