brew config
==> Downloading https://mirrors.ustc.edu.cn/homebrew-bottles/bottles/bottles-portable-ruby/portable-ruby-2.6.8_1.el_capitan.bottle.tar.gz
curl: (22) The requested URL returned error: 404
==> Downloading https://ghcr.io/v2/homebrew/portable-ruby/portable-ruby/blobs/sha256:1f50bf80583bd436c9542d4fa5ad47df0ef0f0bea22ae710c4f04c42d7560bca
curl: (35) error:02FFF036:system library:func(4095):Connection reset by peer
==> Downloading https://github.com/Homebrew/homebrew-portable-ruby/releases/download/2.6.8_1/portable-ruby-2.6.8_1.el_capitan.bottle.tar.gz
https://github.com/Homebrew/homebrew-portable-ruby/releases/download/2.6.8_1/portable-ruby-2.6.8_1.el_capitan.bottle.tar.gz##O#- curl: (35) LibreSSL SSL_connect: SSL_ERROR_SYSCALL in connection to github.com:443
Error: Failed to download ruby from the following locations:
- https://mirrors.ustc.edu.cn/homebrew-bottles/bottles/bottles-portable-ruby/portable-ruby-2.6.8_1.el_capitan.bottle.tar.gz
- https://ghcr.io/v2/homebrew/portable-ruby/portable-ruby/blobs/sha256:1f50bf80583bd436c9542d4fa5ad47df0ef0f0bea22ae710c4f04c42d7560bca
- https://github.com/Homebrew/homebrew-portable-ruby/releases/download/2.6.8_1/portable-ruby-2.6.8_1.el_capitan.bottle.tar.gz
Do not file an issue on GitHub about this; you will need to figure out for
yourself what issue with your internet connection restricts your access to
GitHub (used for Homebrew updates and binary packages).
Error: Failed to upgrade Homebrew Portable Ruby!
1、在GitHub下载，该文件，解压portable-ruby-2.6.8_1.el_capitan.bottle.tar.gz，得到 portable-ruby 文件夹，进入
https://github.com/Homebrew/homebrew-portable-ruby/releases/download/2.6.8_1/portable-ruby-2.6.8_1.el_capitan.bottle.tar.gz
2、解压portable-ruby-2.6.8_1.el_capitan.bottle.tar.gz，得到 portable-ruby 文件夹，进入portable-ruby，拷贝里面的 2.6.8_1 文件夹到 "/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby"
3、制作一个current的快捷方式指向“2.6.8_1”文件夹。（command + option 拖动文件夹可以制作框架方式）
参考：
https://blog.csdn.net/u013670453/article/details/113915555