Day 22 Linux的文件权限
第1章 Linux 权限 permission denied
1.1 对于文件rwx含义
模拟环境
[root@oldboyedu50-lnb ~]# mkdir -p /oldboy
[root@oldboyedu50-lnb ~]# echo 'hostname' >/oldboy/test.sh
[root@oldboyedu50-lnb ~]# cat /oldboy/test.sh
hostname
[oldboy@oldboyedu50-lnb /oldboy]$ ll test.sh
-rw-r--r--. 1 root root 9 Aug 6 12:32 test.sh
[oldboy@oldboyedu50-lnb /oldboy]$ cat test.sh
hostname
[oldboy@oldboyedu50-lnb /oldboy]$ echo 'pwd' >>test.sh
-bash: test.sh: Permission denied
[oldboy@oldboyedu50-lnb /oldboy]$ /oldboy/test.sh
-bash: /oldboy/test.sh: Permission denied
[root@oldboyedu50-lnb /oldboy]# chown oldboy.oldboy test.sh
[root@oldboyedu50-lnb /oldboy]# ll test.sh
-rw-r--r--. 1 oldboy oldboy 9 Aug 6 12:32 test.sh
1.1.1 #root用户下面修改权限 测试r权限
#oldboy用户只有r 权限
[root@oldboyedu50-lnb /oldboy]# chmod u=r test.sh
[root@oldboyedu50-lnb /oldboy]# ll test.sh
-r--r--r--. 1 oldboy oldboy 9 Aug 6 12:32 test.sh
#oldboy用户下面测试
[oldboy@oldboyedu50-lnb /oldboy]$ ll test.sh
-r--r--r--. 1 oldboy oldboy 9 Aug 6 12:32 test.sh
[oldboy@oldboyedu50-lnb /oldboy]$ cat test.sh
hostname
[oldboy@oldboyedu50-lnb /oldboy]$ echo 'pwd'>>test.sh
-bash: test.sh: Permission denied
[oldboy@oldboyedu50-lnb /oldboy]$ /oldboy/test.sh
-bash: /oldboy/test.sh: Permission denied
1.2 #root用户下面修改权限 测试w权限
#oldboy用户只有w 权限
[root@oldboyedu50-lnb /oldboy]# chmod u=w test.sh
[root@oldboyedu50-lnb /oldboy]# ll test.sh
--w-r--r--. 1 oldboy oldboy 9 Aug 6 12:32 test.sh
#oldboy用户下面测试
[oldboy@oldboyedu50-lnb /oldboy]$ ll test.sh
--w-r--r--. 1 oldboy oldboy 9 Aug 6 12:32 test.sh
[oldboy@oldboyedu50-lnb /oldboy]$ cat test.sh
cat: test.sh: Permission denied
[oldboy@oldboyedu50-lnb /oldboy]$ echo 'pwd' >>test.sh
[oldboy@oldboyedu50-lnb /oldboy]$ echo 'pwd' >>test.sh
[oldboy@oldboyedu50-lnb /oldboy]$ echo 'pwd' >>test.sh
[oldboy@oldboyedu50-lnb /oldboy]$ echo 'pwd' >>test.sh
[oldboy@oldboyedu50-lnb /oldboy]$ cat test.sh
cat: test.sh: Permission denied
[oldboy@oldboyedu50-lnb /oldboy]$
[oldboy@oldboyedu50-lnb /oldboy]$ /oldboy/test.sh
-bash: /oldboy/test.sh: Permission denied
1.3 #root用户下面修改权限 测试x权限
#oldboy用户 只有x 权限
[root@oldboyedu50-lnb /oldboy]# chmod u=x test.sh
[root@oldboyedu50-lnb /oldboy]# ll test.sh
---xr--r--. 1 oldboy oldboy 13 Aug 6 12:56 test.sh
#oldboy用户下面测试
[oldboy@oldboyedu50-lnb /oldboy]$ ll test.sh
---xr--r--. 1 oldboy oldboy 13 Aug 6 12:56 test.sh
[oldboy@oldboyedu50-lnb /oldboy]$ cat test.sh
cat: test.sh: Permission denied
[oldboy@oldboyedu50-lnb /oldboy]$ echo 'pwd' >>test.sh
-bash: test.sh: Permission denied
[oldboy@oldboyedu50-lnb /oldboy]$ /oldboy/test.sh
bash: /oldboy/test.sh: Permission denied
1.4 文件的rwx权限小结:
1.4.1 r读取文件内容
1.4.2 w修改文件内容 需要r权限配合 只有w权限的时候 强制保存退出会导致源文件内容丢失
1.4.3 x权限表示是否能执行脚本 需要r权限配合
2.1对于目录rwx含义
创建环境
mkdir -p /oldboy/test
touch /oldboy/test/oldboy{01..5}.txt
chown oldboy.oldboy /oldboy/test/
[root@oldboyedu50-lnb /oldboy]# ll /oldboy/test -d
drwxr-xr-x. 2 oldboy oldboy 4096 Aug 6 13:02 /oldboy/test
[root@oldboyedu50-lnb /oldboy]# ll /oldboy/test
total 4
-rw-r--r--. 1 root root 8 Jul 16 19:24 del.sh
-rw-r--r-- 1 root root 0 Aug 6 13:02 oldboy01.txt
-rw-r--r-- 1 root root 0 Aug 6 13:02 oldboy02.txt
-rw-r--r-- 1 root root 0 Aug 6 13:02 oldboy03.txt
-rw-r--r-- 1 root root 0 Aug 6 13:02 oldboy04.txt
-rw-r--r-- 1 root root 0 Aug 6 13:02 oldboy05.txt
r 查看目录内容 ls
w 可以删除 创建 重命名 目录中的文件
x 是否能进入到目录 cd
2.2#root用户下面修改权限 测试r权限
#oldboy用户 只有r 权限
[root@oldboyedu50-lnb /oldboy]# chmod u=r test
[root@oldboyedu50-lnb /oldboy]# ll -d test
dr--r-xr-x. 2 oldboy oldboy 4096 Aug 6 13:02 test
#oldboy用户下面测试
[oldboy@oldboyedu50-lnb /oldboy]$ ls test
ls: cannot access test/oldboy05.txt: Permission denied
ls: cannot access test/oldboy04.txt: Permission denied
ls: cannot access test/oldboy01.txt: Permission denied
ls: cannot access test/del.sh: Permission denied
ls: cannot access test/oldboy02.txt: Permission denied
ls: cannot access test/oldboy03.txt: Permission denied
del.sh oldboy01.txt oldboy02.txt oldboy03.txt oldboy04.txt oldboy05.txt
[oldboy@oldboyedu50-lnb /oldboy]$ ls -l test
ls: cannot access test/oldboy05.txt: Permission denied
ls: cannot access test/oldboy04.txt: Permission denied
ls: cannot access test/oldboy01.txt: Permission denied
ls: cannot access test/del.sh: Permission denied
ls: cannot access test/oldboy02.txt: Permission denied
ls: cannot access test/oldboy03.txt: Permission denied
total 0
-????????? ? ? ? ? ? del.sh
-????????? ? ? ? ? ? oldboy01.txt
-????????? ? ? ? ? ? oldboy02.txt
-????????? ? ? ? ? ? oldboy03.txt
-????????? ? ? ? ? ? oldboy04.txt
-????????? ? ? ? ? ? oldboy05.txt
2.3w 代表是否能删除目录内容 在目录中创建文件 重命名 需要与x配合
[root@oldboy50-lnb /oldboy]#chmod u=w test
[root@oldboy50-lnb /oldboy]#ll -d test
d-w-r-xr-x 2 oldboy oldboy 4096 Aug 2 12:57 test
[oldboy@oldboy50-lnb /oldboy]$cd test
-bash: cd: test: Permission denied
[oldboy@oldboy50-lnb /oldboy]$ls test
ls: cannot open directory test: Permission denied
[oldboy@oldboy50-lnb /oldboy]$touch 1.txt test
touch: cannot touch `1.txt': Permission denied
2.4x权限是否能进入目录 cd (你是否能查看目录中文件的属性)
[root@oldboy50-lnb /oldboy]#chmod u=x test
[root@oldboy50-lnb /oldboy]#ll -d test
d--xr-xr-x 2 oldboy oldboy 4096 Aug 2 14:22 test
[oldboy@oldboy50-lnb /oldboy]$ls test
ls: cannot open directory test: Permission denied
[oldboy@oldboy50-lnb /oldboy]$cd test
[oldboy@oldboy50-lnb /oldboy/test]$touch 1.txt test
touch: cannot touch `1.txt': Permission denied
touch: cannot touch `test': Permission denied
2.5目录权限小结:
2.5.1 r 显示目录内容 需要x权限配合
2.5.2 w 是否能删除目录内容 在目录中创建文件 修改(重命名)
2.5.3 x 是否能进入到目录 cd (你是否能查看目录中文件的属性)
2.5.4 删除一个文件 看文件所在目录的权限 是否有wx权限
2.6说说下面错误的报错原因:
1.
[oldboy@oldboyedu50-lnb /]$ ls /root/
ls: cannot open directory /root/: Permission denied 没有r和x权限
2.
[oldboy@oldboyedu50-lnb /]$ touch /etc/passwd.txt
touch: cannot touch `/etc/passwd.txt': Permission denied 没有w权限,x和w配合
3.
[oldboy@oldboyedu50-lnb /]$ \rm -f /etc/sysconfig/network
rm: cannot remove `/etc/sysconfig/network': Permission denied 没有w权限wx配合
4.
[oldboy@oldboyedu50-lnb /]$ echo '#oldboy' >>/etc/hosts
-bash: /etc/hosts: Permission denied 没有w权限rw配合
5.
[oldboy@oldboyedu50-lnb /]$ cat /etc/shadow
cat: /etc/shadow: Permission denied 没有r权限
2.7文件访问过程与权限
cat oldboy.txt
inode block
文件 文件属性 数据(文件内容)
目录 目录属性 文件名
cat /oldboy/lidao/test.sh
权限可能与文件所在的目录及上级目录 及 目录有关
控制系统默认权限 umask
文件一般可以给的最大权限:666
文件默认的权限 特殊情况 umask 为单数 032文件 遇到奇数减完加一 目录没有此规则
666 666
-022 -032
=644 634
+010
=644
目录一般可以给的最大权限:777
目录默认的权限
777
-022
=755
umask是 035 系统文件默认权限是? 目录权限是?
文件
666
-035
=631
+011
642
目录
777
035
742
要求创建的文件默认权限是000,目录的权限是111 umask ?
umask==666
2.8如何通过控制权限的方法 保护网站安全
网站 blog.oldboyedu.com
/app/blog
2.8.1 网站通过www用户运行(虚拟用户)
2.8.2控制目录/app/blog 权限
file 644 root root
dir 755 root root
2.8.3网站上传目录upload
file 644 www www
dir 755 www www
2.9例题
模拟环境
mkdir -p /app/blog /app/blog/upload
touch /app/blog/tao.avi /app/blog/dao.mp4 /app/blog/ndd.torrent
useradd www
[www@oldboyedu50-lnb /app/blog]$ touch upload/499G.torrent
touch: cannot touch `upload/499G.torrent': Permission denied
#什么原因及怎么解决
[root@oldboyedu50-lnb /oldboy]# chown www.www /app/blog/upload/
2.10网站整体结构
[root@oldboyedu50-lnb /oldboy]# chattr +a test.sh
[root@oldboyedu50-lnb /oldboy]# lsattr test.sh
-----a-------e- test.sh
[root@oldboyedu50-lnb /oldboy]# #a append 只能追加不能删除无法修改
[root@oldboyedu50-lnb /oldboy]# #i 无法删除无法修改只能看
[root@oldboyedu50-lnb /oldboy]# >test.sh
-bash: test.sh: Operation not permitted
[root@oldboyedu50-lnb /oldboy]# echo pwd >>test.sh
[root@oldboyedu50-lnb /oldboy]# \rm -f test.sh
rm: cannot remove `test.sh': Operation not permitted