root@mission:/etc/apt# apt-get update
Err:1 http://mirrors.ustc.edu.cn/ubuntu focal InRelease
System error resolving 'mirrors.ustc.edu.cn:http' - getaddrinfo (16: Device or resource busy)
Err:2 http://mirrors.ustc.edu.cn/ubuntu focal-updates InRelease
System error resolving 'mirrors.ustc.edu.cn:http' - getaddrinfo (16: Device or resource busy)
Err:3 http://mirrors.ustc.edu.cn/ubuntu focal-backports InRelease
System error resolving 'mirrors.ustc.edu.cn:http' - getaddrinfo (16: Device or resource busy)
Err:4 http://mirrors.ustc.edu.cn/ubuntu focal-security InRelease
System error resolving 'mirrors.ustc.edu.cn:http' - getaddrinfo (16: Device or resource busy)
Err:5 http://archive.canonical.com/ubuntu focal InRelease
System error resolving 'archive.canonical.com:http' - getaddrinfo (16: Device or resource busy)
Reading package lists... Done
W: Failed to fetch http://mirrors.ustc.edu.cn/ubuntu/dists/focal/InRelease System error resolving 'mirrors.ustc.edu.cn:http' - getaddrinfo (16: Device or resource busy)
W: Failed to fetch http://mirrors.ustc.edu.cn/ubuntu/dists/focal-updates/InRelease System error resolving 'mirrors.ustc.edu.cn:http' - getaddrinfo (16: Device or resource busy)
W: Failed to fetch http://mirrors.ustc.edu.cn/ubuntu/dists/focal-backports/InRelease System error resolving 'mirrors.ustc.edu.cn:http' - getaddrinfo (16: Device or resource busy)
W: Failed to fetch http://mirrors.ustc.edu.cn/ubuntu/dists/focal-security/InRelease System error resolving 'mirrors.ustc.edu.cn:http' - getaddrinfo (16: Device or resource busy)
W: Failed to fetch http://archive.canonical.com/ubuntu/dists/focal/InRelease System error resolving 'archive.canonical.com:http' - getaddrinfo (16: Device or resource busy)
W: Some index files failed to download. They have been ignored, or old ones used instead.
可以定位为网络问题
1. 查看是否禁用ip
root@mission:~# cat /proc/sys/net/ipv4/ip_forward
1
0表示禁用，需要开启
nano /etc/sysctl.conf
打开内核配置文件，查找net.ipv4.ip_forward = 0，将其修改为net.ipv4.ip_forward = 1
2. 重启
root@mission:~# sysctl -p /etc/sysctl.conf
root@mission:~# apt-get update