Linux使用所遇见的问题以及解决方法

1、Ubuntu20.04更换软件下载源

编辑/etc/apt/sources.list文件, 在文件最前面添加以下条目(操作前请做好相应备份)：

sudo gedit /etc/apt/sources.list

然后更好为下面的这些源

清华源：

# 默认注释了源码镜像以提高 apt update 速度，如有需要可自行取消注释
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security main restricted universe multiverse

# 预发布软件源，不建议启用
# deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-proposed main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-proposed main restricted universe multiverse

阿里源：

deb http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse

中科大源：

deb https://mirrors.ustc.edu.cn/ubuntu/ focal main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ focal main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ focal-updates main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ focal-updates main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ focal-backports main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ focal-backports main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ focal-security main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ focal-security main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ focal-proposed main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ focal-proposed main restricted universe multiverse

换好源之后需要从新加载那些软件包：

sudo apt-get update
sudo apt-get upgrade

2、出现换源之后出现无法连接网络

错误:1 http://mirrors.aliyun.com/ubuntu focal InRelease   暂时不能解析域名“mirrors.aliyun.com”

解决方式1

1、查看当前网络标志是不是存在

2、如果不存在则单击鼠标右键，点击设置

3、手动进行网络的关闭以及打开，直到网络图标是存在的

3、遇见问题

/usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/crt1.o：在函数‘_start’中： (.text+0x20)：对‘main’未定义的引用 collect2: error: ld returned 1 exit status

遇见此问题，说明你的程序里面没用主函数main（）

int main(int argc,int *argv[]){}

也有可能是你的参数没有添加。