问题

安装umi时报错 'E:\Program' 不是内部或外部命令，也不是可运行的程序

PS D:\project\myapp> yarn create umi
yarn create v1.17.3
[1/4] Resolving packages...
[2/4] Fetching packages...
[3/4] Linking dependencies...
[4/4] Building fresh packages...
success Installed "create-umi@0.17.1" with binaries:
      - create-umi
'E:\Program' 不是内部或外部命令，也不是可运行的程序
error Command failed.
Command: E:\Program Files (x86)\Yarn\bin\create-umi
Directory: D:\project\myapp

info Visit https://yarnpkg.com/en/docs/cli/create for documentation about this command.

PS D:\project\myapp> yarn global bin
E:\Program Files (x86)\Yarn\bin

解决办法

PS D:\project\myapp> yarn global add create-umi --prefix "E:\Program Files (x86)\Yarn\bin"
yarn global v1.17.3
[1/4] Resolving packages...
[2/4] Fetching packages...
[3/4] Linking dependencies...
[4/4] Building fresh packages...
success Installed "create-umi@0.17.1" with binaries:
      - create-umi
Done in 28.19s.

原理

执行yarn create umi命令时，因为 yarn global bin目录E:\Program Files (x86)\Yarn\bin'中有空格，空格前后被误当成两个命令参数（windows cmd命令参数分隔符默认为空格），所以报错。
yarn create umi等同于yarn global add create-umi --prefix "E:\Program Files (x86)\Yarn\bin"，后者用引号将路径引起来就不会报错了。