我想sudo apt-get install git在我的 ubuntu 14.04 上安装 git 后安装 git。日志在这里：
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package git is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
git-man
E: Package 'git' has no installation candidate
然后，按照这个问题，我运行 git-core 而不是 git 但也失败了。顺便说一句我也尝试过apt-get update。
之后，我尝试了这个问题的答案。前面两条命令都没有问题，但是输入最后一条命令后，仍然出错。日志在这里： …