bash - 在 Bash 中自定义 "command not found"消息

Question

有什么办法可以改变 Bash 系统错误消息模板，以便您可以在原始消息之外打印一些内容吗？例如:

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

或

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

Answer 1

自 Bash 4.0 起，如果搜索命令不成功，shell 将搜索名为 command_not_found_handle 的函数。如果它不存在，Bash 会打印这样的消息并以状态 127 退出:

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

如果它确实存在，它会用命令及其参数作为参数调用，所以如果你有类似的东西

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

在你的 .bashrc 中，Bash 会这样 react :

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

不过，大多数系统都有更复杂的东西。例如，我的 Ubuntu 在 /etc/bash.bashrc 中有这个:

# 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

这来自 /etc/profile。 /usr/lib/command-not-found 是一个 Python 脚本，它使用更多的 Python (CommandNotFound) 来基本上查找名称类似于未知命令的包，或者听起来很相似:

$ 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

所以如果你想要简单的定制，你可以提供你自己的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。