如何取得/etc/hosts文件的權限對應的數字內容，如-rw-r--r--爲644，要求使用命令取得644這樣的數字。
解答：
[root@oldboyedu-39-nb ~]# stat /etc/hosts
File: `/etc/hosts'
Size: 216 Blocks:8 IO Block: 4096 regular file
Device: 803h/2051d Inode:260126 Links: 2
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2017-07-30 00:02:05.983001919 +0800
Modify: 2017-05-20 22:57:33.530934887 +0800
Change: 2017-05-20 22:57:33.533934704 +0800
[root@oldboyedu-39-nb ~]# stat /etc/hosts|awk 'NR==4'
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
[root@oldboyedu-39-nb ~]# stat /etc/hosts|awk 'NR==4'|sed's#^.*(0##g'
644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
方法一：sed去掉前面，去掉後面
[root@oldboyedu-39-nb ~]# stat /etc/hosts|awk 'NR==4'|sed 's#^.*(0##g'|sed's#/.*$##g'
644
方法二：sed反向引用
[root@oldboyedu39 ~]# stat /etc/hosts | sed -n '4p' | sed -r's#^.*\((.*)/-.*$#\1#g'
0644
[root@oldboyedu39 ~]#
[root@oldboyedu39 ~]# stat /etc/hosts | sed -n '4p' | sed -r's#^.*\(0(.*)/-.*$#\1#g'
644
方法三：awk分隔用法菜刀系列
[root@oldboyedu39 ~]# stat /etc/hosts | awk 'NR==4' |awk -F "[0/]"'{print $2}'
644
[root@oldboyedu39 ~]#
[root@oldboyedu39 ~]# stat /etc/hosts | awk 'NR==4' |awk -F "[0/]"'{print $2}'
644
[root@oldboyedu39 ~]#
[root@oldboyedu39 ~]# stat /etc/hosts | awk -F "[0/]" 'NR==4{print$2}'
644
[root@oldboyedu39 ~]#
[root@oldboyedu39 ~]# stat /etc/hosts | awk -F "[(/]" 'NR==4{print$2}'
0644
4.命令的結果裏面有你想要的東西----可能會有現成參數
# stat-c%a /etc/hosts
644