在Bash中自定义“command not found”消息

Question

有没有办法更改Bash系统错误消息模板，以便除了原始消息之外还可以打印某些内容？例如：

Macbook Air:~/Public]$ lfe 
-bash: lfe: WTF command not found 

或

Macbook Air:~/Public]$ lfe 
-bash: lfe: #!&**! command not found 

Answer 1

也许是这样的：

curl https://raw.githubusercontent.com/rcaloras/bash-preexec/master/bash-preexec.sh -o ~/.bash-preexec.sh 
echo '[[ -f ~/.bash-preexec.sh ]] && source ~/.bash-preexec.sh' >> ~/.bashrc 

然后添加以下到.bashrc太

preexec() { type "$1" >/dev/null 2>&1 || echo -n 'WTF??? '; } 

重装你的shell，然后尝试输入一些不存在的命令，如bububu

$ bububu 

将打印

WTF??? -bash: bububu: command not found 

重要：读https://github.com/rcaloras/bash-preexec

Answer 2

由于猛砸4.0，如果搜索的命令不成功，shell搜索名为command_not_found_handle的函数。如果它不存在，Bash打印类似这样的消息，并与状态127退出：

$ foo 
-bash: foo: command not found 
$ echo $? 
127 

如果确实存在，它被称为用命令和它作为参数的参数，所以如果你有什么像

command_not_found_handle() { 
    echo "It's my handle!" 
    echo "Arguments: $@" 
} 

在.bashrc，bash将这样的反应：

$ foo bar 
It's my handle! 
Arguments: foo bar 

大多数系统都有一些更诡辩尽管如此。我的Ubuntu，例如，有这样的/etc/bash.bashrc：

# if the command-not-found package is installed, use it 
if [ -x /usr/lib/command-not-found -o -x /usr/share/command-not-found/command-not-found ]; then 
    function command_not_found_handle { 
      # check because c-n-f could've been removed in the meantime 
       if [ -x /usr/lib/command-not-found ]; then 
      /usr/lib/command-not-found -- "$1" 
        return $? 
       elif [ -x /usr/share/command-not-found/command-not-found ]; then 
      /usr/share/command-not-found/command-not-found -- "$1" 
        return $? 
     else 
      printf "%s: command not found\n" "$1" >&2 
      return 127 
     fi 
    } 
fi 

，这是从/etc/profile来源。 /usr/lib/command-not-found是使用一些Python的（CommandNotFound）基本上查找该被命名为喜欢未知的命令包，或​​声音类似Python脚本：

$ sl 
The program 'sl' is currently not installed. You can install it by typing: 
sudo apt install sl 
$ sedd 
No command 'sedd' found, did you mean: 
Command 'sed' from package 'sed' (main) 
Command 'seedd' from package 'bit-babbler' (universe) 
Command 'send' from package 'nmh' (universe) 
Command 'send' from package 'mailutils-mh' (universe) 
sedd: command not found 

所以，如果你想简单的定制，你可以提供自己的command_not_found_handle ，如果你想定制现有的系统，你可以修改Python脚本。

但是，如前所述，这需要Bash 4.0或更高版本。