【Perl】" "\w" is unrecognized escape " in grep issue

在用Perl 调用 grep时遇到如下提示“"\w" is unrecognized escape”，

$build_num = `find ./ -type d -maxdepth | grep -E "Linux/\w+" | wc -l `;

 Solution :

  反斜线前面需要再加一个反斜线。

$build_num = `find ./ -type d -maxdepth | grep -E "Linux/\\w+" | wc -l `;