Homebrew是一款自由及开放源代码的软件包管理系统，用以简化macOS系统上的软件安装过程。对于Appstore中没有的软件，推荐使用此方法安装管理第三方软件。
没有安装Homebrew，可以参考MacOS 安装 HomeBrew
1、安装命令：brew install telnet
Error: The following directories are not writable by your user:
/usr/local/share/man/man8
You should change the ownership of these directories to your user.
sudo chown -R $(whoami) /usr/local/share/man/man8
And make sure that your user has write permission.
chmod u+w /usr/local/share/man/man8
2、提示无法安装，需要执行如下命令，即可安装。
sudo chown -R $(whoami) /usr/local/share/man/man8
chmod u+w /usr/local/share/man/man8
3、brew install telnet
==> Downloading https://mirrors.ustc.edu.cn/homebrew-bottles/bottles/telnet-63.m
######################################################################## 100.0%
==> Pouring telnet-63.monterey.bottle.tar.gz
🍺 /usr/local/Cellar/telnet/63: 4 files, 174.8KB
==> Running `brew cleanup telnet`...
Disable this behaviour by setting HOMEBREW_NO_INSTALL_CLEANUP.
Hide these hints with HOMEBREW_NO_ENV_HINTS (see `man brew`).
4、查看telnet版本
telnet -v
telnet: illegal option -- v
usage: telnet [-4] [-6] [-8] [-E] [-K] [-L] [-N] [-S tos] [-X atype] [-c] [-d]
[-e char] [-k realm] [-l user] [-f/-F] [-n tracefile] [-r] [-s src_addr] [-u] [-P policy] [host-name [port]]
