今天升级了os catalina
1：在使用命令台时出现了：
the default interactive shell is now zsh. to update your account to use zsh, please run `chsh -s /bin/zsh`. for more details, please visit https://support.apple.com/kb/ht208050.
2：原我使用的是bash风格，提示语告知现在新系统的shell已经更换为zsh，请用此 `chsh -s /bin/zsh` 命令切换。
3：查看系统支持的shell风格命令：
cat /etc/shells
4：我系统支持的shell：
the default interactive shell is now zsh.
to update your account to use zsh, please run `chsh -s /bin/zsh`.
for more details, please visit https://support.apple.com/kb/ht208050.
localhost:~ yuzhilin$ cat /etc/shells
# list of acceptable shells for chpass(1).
# ftpd will not allow users to connect who are not using
# one of these shells.
/bin/bash
/bin/csh
/bin/dash
/bin/ksh
/bin/sh
/bin/tcsh
/bin/zsh
localhost:~ yuzhilin$
5：解决办法
(1) 不使用bash，切换zsh，`chsh -s /bin/zsh`命令切换即可。
(2) 继续使用bash，但又不想出现提示语，则在
vim ~/.bash_profile
.bash_profile文件最下方加上
# macos catalina
export bash_silence_deprecation_warning=1
:wq 保存退出重新打开命令行警示语消失。
