1.mac os在10.15.3中是沒telnet命令的，安裝命令如下
brew install telnet
但是會出現Updating Homebrew…一直卡在這裏不動，在這個時候不需要做過多的操作，有一個小技巧，按下Ctrl+C就開始下載了…
yaomingyang:~ yaomingyang$ brew install telnet
Updating Homebrew...
^C==> Downloading https://homebrew.bintray.com/bottles/telnet-60.catalina.bottle.t
######################################################################## 100.0%
==> Pouring telnet-60.catalina.bottle.tar.gz
🍺 /usr/local/Cellar/telnet/60: 4 files, 138.1KB
==> `brew cleanup` has not been run in 30 days, running now...
Pruned 1 symbolic links from /usr/local
2.測試安裝是否成功
yaomingyang:~ yaomingyang$ telnet
telnet>
3.查看telnet可執行文件位置
yaomingyang:~ yaomingyang$ which telnet
/usr/local/bin/telnet
