我正在尝试在Ubuntu 20.4.1 LTS上安装dotenet ef。
首先，我在全局范围内安装了该工具：
dotnet tool install --global dotnet-ef
因为它不工作，所以我把这个PATH引用添加到我的.bashrc文件的dotnet工具文件夹中：
export PATH="$PATH:$HOME/.dotnet/tools/"
如此处所示：Cannot find command 'dotnet ef'?
然而，当我尝试运行dotnet ef时，我收到以下错误消息：

Could not execute because the specified command or file was not found.
Possible reasons for this include:
  * You misspelled a built-in dotnet command.
  * You intended to execute a .NET Core program, but dotnet-ef does not exist.
  * You intended to run a global tool, but a dotnet-prefixed executable with this name could not be found on the PATH.

有趣的是，如果我尝试再次安装它，我被告知它已经安装。

Tool 'dotnet-ef' is already installed.

但如果我尝试使用dotnet tool list列出已安装的工具，则会得到一个空结果：

Tool 'dotnet-ef' is already installed.

我还检查了我的~/.dotnet/tools/文件夹，它是空的。
我错过了什么？