问.net核心heroku应用程序中的"dotnet-ef不存在“

EN

  <Target Name="PrePublishTarget" AfterTargets="Publish">
    <Exec Command="dotnet tool install --global dotnet-ef" />
    <Exec Command="dotnet ef database update" />
  </Target>

  You can invoke the tool using the following command: dotnet-ef
  Tool 'dotnet-ef' (version '3.1.3') was successfully installed.
  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.
/tmp/build_35cf57c00fbf62634ac8d644c6e8f4f7/BugTracker.csproj(38,5): error MSB3073: The command "dotnet ef database update" exited with code 1.
 !     Push rejected, failed to compile ASP.NET Core app.
 !     Push failed