root@DESKTOP-OscarAu:~# sudo apt-get install daemonize
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package daemonize
root@DESKTOP-OscarAu:~# vi /etc/apt/sources.list
root@DESKTOP-OscarAu:~# sudo apt update
Err:1 http://cn.archive.ubuntu.com/ubuntu focal InRelease
Temporary failure resolving 'cn.archive.ubuntu.com'
Err:2 http://security.ubuntu.com/ubuntu focal-security InRelease
Temporary failure resolving 'security.ubuntu.com'
Err:3 http://cn.archive.ubuntu.com/ubuntu focal-updates InRelease
Temporary failure resolving 'cn.archive.ubuntu.com'
Err:4 http://cn.archive.ubuntu.com/ubuntu focal-backports InRelease
Temporary failure resolving 'cn.archive.ubuntu.com'
Reading package lists... Done
Building dependency tree
Reading state information... Done
All packages are up to date.
W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/focal/InRelease Temporary failure resolving 'cn.archive.ubuntu.com'
W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/focal-updates/InRelease Temporary failure resolving 'cn.archive.ubuntu.com'
W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/focal-backports/InRelease Temporary failure resolving 'cn.archive.ubuntu.com'
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/focal-security/InRelease Temporary failure resolving 'security.ubuntu.com'
W: Some index files failed to download. They have been ignored, or old ones used instead.
改个源看看
https://mirrors.tuna.tsinghua.edu.cn/help/ubuntu/