你不能这样做，因为bash首先处理重定向，然后执行命令。所以当grep查看file_name时，它已经是空的。你可以使用一个临时文件。

You cannot do that because bash processes the redirections first, then executes the command. So by the time grep looks at file_name, it is already empty. You can use a temporary file though.

grep -v 'seg[0-9]\{1,\}\.[0-9]\{1\}' file_name > tmpfile
cat tmpfile > file_name

这样，考虑使用 mktemp 来创建 tmpfile 但请注意它不是POSIX。

like that, consider using mktemp to create the tmpfile but note that it's not POSIX.