extra characters at the end of g command

使用sed命令替換文本內容的時候出現報錯，如下

 sed -i 's/HostName/#HostName/g' /Users/gwd/.ssh/config 

sed: 1: "/Users/gwd/.ssh/config": extra characters at the end of g command

報錯“sed: 1: "/Users/gwd/.ssh/config": extra characters at the end of g command”，原因在於在OS X需要顯式指定擴展名，解決方案是設置一個空字符串，即執行以下命令即可

 sed -i '' 's/HostName/#HostName/g' /Users/gwd/.ssh/config