经过数天的搜索并且在这里和@Angular github上都没有帮助，这几乎没有用，终于能够解决问题并得到我的帮助.通过以下步骤解决了ng命令找不到问题:

After days of googling and getting no help neither on here nor from @Angular github which is pretty much useless, was finally able to resolve the issue and get my angular ng command not found issue resolved following these steps:

1.安装nvm

发出这3条命令以安装nvm. (Angular文档中的步骤 https://angular.io/guide/setup-local 可以设置您的环境不适用于我).

Issue these 3 commands to install nvm. (Angular documented steps https://angular.io/guide/setup-local to setup your environment did not work for me).

所以我像这样安装了nvm:

So I installed nvm like so:

curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.0/install.sh | bash

export NVM_DIR="/Users/your-user-name/.nvm"

[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"

此后，请确保重新启动终端，并且应该能够发出nvm --version来查看已安装的nvm的版本.

After this, make sure you restart terminal and you should be able to issue nvm --version to see version of installed nvm.

2.使用nvm安装节点

nvm install stable

nvm install node

3.最后，安装angular

npm install -g @angular/cli

4.重新启动终端

重新启动终端，您应该可以使用ng version查看系统上安装的版本

Restart terminal and you should be able to use ng version to see version installed on your system

 ~~ ng version


     _                      _                 ____ _     ___
    / \   _ __   __ _ _   _| | __ _ _ __     / ___| |   |_ _|
   / △ \ | '_ \ / _` | | | | |/ _` | '__|   | |   | |    | |
  / ___ \| | | | (_| | |_| | | (_| | |      | |___| |___ | |
 /_/   \_\_| |_|\__, |\__,_|_|\__,_|_|       \____|_____|___|
                |___/


Angular CLI: 8.3.6
Node: 12.11.1
OS: darwin x64
Angular: 
... 

Package                      Version
------------------------------------------------------
@angular-devkit/architect    0.803.6
@angular-devkit/core         8.3.6
@angular-devkit/schematics   8.3.6
@schematics/angular          8.3.6
@schematics/update           0.803.6
rxjs                         6.4.0

我现在可以创建并启动我的项目

I can now create and start my project

ng new my-test-project

ng serve my-test project

我认为SO应该开始认真对待人们拒绝投票的问题或将其标记为重复项，然后再阅读它们，甚至试图理解所问的内容和问题所在.

I think SO should start getting serious about people down-voting questions or marking them as duplicates before reading them and even trying to understand what was asked and what the problem is.

似乎有很多人阅读标题并据此决定问题的命运，任何分歧最终都会完全阻止问题.

It seems to be lots of people read the title and decide the fate of question just based on that and any disagreement ends up in blocking question entirely.

本该提供帮助的网站上存在太多偏见和仇恨.

So much bias and hate on a site that is supposed to help.

非常需要更好的选择.

更新

如果您像我一样，并改用zsh shel代替bash shell(因为Catalina MacOs现在使用zsh)，您可能已经注意到ng version已经停止为您工作.

If you are like me and switched to use zsh shel instead of bash shell (since Catalina MacOs now uses zsh), you might have noticed that ng version has stopped working for you.

在这种情况下，请在vim中打开您的.zshrc文件:

In that case, modify your .zshrc file by opening it in vim:

vi ~/.zshrc

在此处找到此行:

source $ZSH/oh-my-zsh.sh

在此行下，添加以下行:

Underneath this line, add following line:

source /Users/Your-User-Name/.bash_profile

通过按Esc键并输入:wq并按Enter键来保存文件

Save the file by hitting Esc key and typing :wq and hitting Enter

重新启动终端

重新发出ng version，您应该在zsh shell中看到它:

Reissue ng version and you should see it in your zsh shell: