终端找不到命令，下载(wget)不能工作。

Question

我想我已经损坏了我的Ubuntu安装，因为它现在没有识别一些终端命令，比如ufw/ some (已经安装了)。结果如下。

-bash: ufw: command not found

另外，sudo apt update --fix-missing不起作用，因为它提供了以下结果。

Err:1 http://security.ubuntu.com/ubuntu focal-security InRelease
  Temporary failure resolving 'security.ubuntu.com'
Err:2 http://lk.archive.ubuntu.com/ubuntu focal InRelease                                                       
  Temporary failure resolving 'lk.archive.ubuntu.com'
Err:3 http://gb.archive.ubuntu.com/ubuntu bionic InRelease                                                      
  Temporary failure resolving 'gb.archive.ubuntu.com'
Err:4 http://ppa.launchpad.net/deadsnakes/ppa/ubuntu focal InRelease      
  Temporary failure resolving 'ppa.launchpad.net'
Err:5 http://lk.archive.ubuntu.com/ubuntu focal-updates InRelease
  Temporary failure resolving 'lk.archive.ubuntu.com'
Err:6 http://ppa.launchpad.net/gluster/glusterfs-3.12/ubuntu focal InRelease
  Temporary failure resolving 'ppa.launchpad.net'
Err:7 http://lk.archive.ubuntu.com/ubuntu focal-backports InRelease
  Temporary failure resolving 'lk.archive.ubuntu.com'
Err:8 http://ppa.launchpad.net/gluster/glusterfs-6/ubuntu focal InRelease
  Temporary failure resolving 'ppa.launchpad.net'
Reading package lists... Done       
Building dependency tree       
Reading state information... Done
All packages are up to date.
W: Failed to fetch http://lk.archive.ubuntu.com/ubuntu/dists/focal/InRelease  Temporary failure resolving 'lk.archive.ubuntu.com'
W: Failed to fetch http://lk.archive.ubuntu.com/ubuntu/dists/focal-updates/InRelease  Temporary failure resolving 'lk.archive.ubuntu.com'
W: Failed to fetch http://lk.archive.ubuntu.com/ubuntu/dists/focal-backports/InRelease  Temporary failure resolving 'lk.archive.ubuntu.com'W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/focal-security/InRelease  Temporary failure resolving 'security.ubuntu.com'
W: Failed to fetch http://gb.archive.ubuntu.com/ubuntu/dists/bionic/InRelease  Temporary failure resolving 'gb.archive.ubuntu.com'
W: Failed to fetch http://ppa.launchpad.net/deadsnakes/ppa/ubuntu/dists/focal/InRelease  Temporary failure resolving 'ppa.launchpad.net'
W: Failed to fetch http://ppa.launchpad.net/gluster/glusterfs-3.12/ubuntu/dists/focal/InRelease  Temporary failure resolving 'ppa.launchpad.net'
W: Failed to fetch http://ppa.launchpad.net/gluster/glusterfs-6/ubuntu/dists/focal/InRelease  Temporary failure resolving 'ppa.launchpad.net'
W: Some index files failed to download. They have been ignored, or old ones used instead.

这发生在我试图将python版本从3.8降到3.5以运行一个特定的程序时，在ubuntu20.2中。我只看到一些评论，并没有建议程序有点晚，现在已经太晚了。

注意:我的路径如下所示，(and it contains bin, /usr/bin and /usr/local/bin)

/home/chameera/.local/bin:/opt/lib/mpich/bin:/opt/lib/netcdf/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin

• 使用wget，不能下载任何文件，但可以使用ssh进出机器，以及传输文件。
• ping到8.8.8.8响应，但不响应www.google.com
• sudo dpkg --configure -a在清除sudo rm /var/lib/apt/lists/lock、sudo rm /var/lib/dpkg/lock、sudo rm /var/lib/dpkg/lock-frontend、sudo rm /var/lib/apt/lists/* -vf中的锁文件后不会生成任何输出。

我还没有重新启动这台机器，因为它是一台远程机器，我有点担心这样做，担心我可能会再次失去对它的访问，直到我身体恢复机器。如果你们能在这方面帮助我，我将不胜感激。

提前谢谢你！

Answer 1

你需要撤销你对python的降级，我不知道你是怎么做到的。

修复后，我建议使用蟒蛇来管理其他python版本(永远不要碰系统python!)或者在另一个目录树(如CPython )中单独安装/opt/python/<version>。使用后一种选项，您可以使用环境模块或Lmod轻松地交换进出的软件版本，类似于python虚拟环境或conda环境。