無法在 Debian 上安裝 i3

我想試試 i3 視窗管理器。當我執行時apt-get install i3遇到以下錯誤；

root@hammerhead:~# apt-get install i3
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package i3

/etc/apt/sources.list這是;的副本

root@hammerhead:~# cat /etc/apt/sources.list
# deb cdrom:[Debian GNU/Linux 9.3.0 _Stretch_ - Official amd64 NETINST 20171209-12:10]/ stretch contrib main non-free

# deb cdrom:[Debian GNU/Linux 9.3.0 _Stretch_ - Official amd64 NETINST 20171209-12:10]/ stretch contrib main non-free

deb http://ftp.uk.debian.org/debian/ stretch main non-free contrib
deb-src http://ftp.uk.debian.org/debian/ stretch main non-free contrib

deb http://security.debian.org/debian-security stretch/updates main contrib non-free
deb-src http://security.debian.org/debian-security stretch/updates main contrib non-free

# stretch-updates, previously known as 'volatile'
deb http://ftp.uk.debian.org/debian/ stretch-updates main contrib non-free
deb-src http://ftp.uk.debian.org/debian/ stretch-updates main contrib non-free

我在這裡想念什麼？

我只能使用這些儲存庫在 Debian Stretch 上安裝 i3：

deb http://deb.debian.org/debian stretch main          
deb-src http://deb.debian.org/debian stretch main

嘗試使用這些儲存庫並執行apt-get update.

引用自：https://unix.stackexchange.com/questions/457690