用perl获取文件的权限更容易

另外：如果其他用户没有根目录的读权限的话，即使在root用户下，用su - 也是无法切换普通用户的。

今天尝试用perl获取权限，在安全加固前备份所有的修改权限的文件的原始权限；

sxb102:/export/home # cat bak.pl
#!/usr/bin/perl
$mode = (stat("./test"))[2];
printf "%04o\n", ($mode & 007777);
sxb102:/export/home # ls -l ./test
-rwsr-xr-x 1 root root 0 Apr 12 23:32 ./test
sxb102:/export/home # stat ./test
File: `./test'
Size: 0              Blocks: 0          IO Block: 4096   regular empty file
Device: 802h/2050d      Inode: 116506      Links: 1
Access: (4755/-rwsr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2008-04-12 23:32:00.000000000 +0800
Modify: 2008-04-12 23:32:00.000000000 +0800
Change: 2008-04-12 23:32:54.000000000 +0800
sxb102:/export/home # chmod 3666 ./test
sxb102:/export/home # ls -l
total 20
-rwxr-xr-x 1 root root 6495 Apr  6 23:20 a
-rw-r--r-- 1 root root  123 Apr  6 23:20 a.c
-rwxr-xr-x 1 root root   20 Apr 12 22:13 a.pl
-rwxr-xr-x 1 root root   80 Apr 12 23:35 bak.pl
-rw-rwSrwT 1 root root    0 Apr 12 23:32 test
sxb102:/export/home # stat ./test
File: `./test'
Size: 0               Blocks: 0          IO Block: 4096   regular empty file
Device: 802h/2050d      Inode: 116506      Links: 1
Access: (3666/-rw-rwSrwT)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2008-04-12 23:32:00.000000000 +0800
Modify: 2008-04-12 23:32:00.000000000 +0800
Change: 2008-04-12 23:35:55.000000000 +0800
sxb102:/export/home # ./bak.pl
3666