$_下划线变量在shell启动时设置，包含shell的绝对文件名或者作为参数列表被执行的脚本。

The underscore variable is set at shell startup and contains the absolute file name of the shell or script being executed as passed in the argument list.

youdao

$_下划线变量在shell启动时设置，包含shell的绝对文件名或者作为参数列表被执行的脚本。

The underscore variable is set at shell startup and contains the absolute file name of the shell or script being executed as passed in the argument list.

youdao