Linux exercise 13 default permissions and special permissions examples

Project 1. Default permissions

1. View the umask values of common users user1 and root users respectively

[root@localhost aoian] # umask
0022
[root@localhost aoian] # useradd user1
root@localhost aoianj # su user1
user1 @localhost aoian] $ umask
0002

2. Use user1 to create a folder dir and file file, and view their attributes

$ mkdir dir
$ touch file
$ ll
drwxrwxr- x.2 user1 userl 6 11月 13 18: 58 dir
-rW-rW-r-- .1 userl userl 0 11月 13 18: 59 file

3. Summarize how the default permissions of new files and folders for ordinary users and root users are determined

The maximum file permission is 666

The maximum permission of the directory is 777

Ordinary user umask-0002

666-002 is 664

777-002 is 775

Calculated that the default permissions of ordinary user files are 664

The default permission of the folder is 775

The same

Root user umask-0022

Calculated that the default file permissions are 644

The default permission of the directory is 755

Item 2. Examples of special permissions

Suppose there are two accounts in the system, user1 and user2. In addition to their own group, these two people also belong to a group named project. Assume that these two users need to jointly own the development rights of the /home/net/ directory, and that the directory does not allow other people to access it. How should the permissions of this directory be set?

[root@localhost aoian]# groupadd project
[root@localhost aoian]# useradd -G project user1
[root@localhost aoian]# useradd -G project user2
[root@localhost aoian]# mkdir /home/net
[root@localhost aoian]# chgrp project /home/net
[root@localhost aoian]# cd /home
[root@localhost home]# ll
总用量 4
drwx------. 16 aoian aoian   4096 10月 16 09:50 aoian
drwxr-xr-x.  2 root  project    6 11月 13 20:44 net
drwx------.  3 user1 user1     78 11月 13 20:43 user1
drwx------.  3 user2 user2     78 11月 13 20:43 user2
[root@localhost home]# chmod 2770 net
[root@localhost home]# ll
总用量 4
drwx------. 16 aoian aoian   4096 10月 16 09:50 aoian
drwxrws---.  2 root  project    6 11月 13 20:44 net
drwx------.  3 user1 user1     78 11月 13 20:43 user1
drwx------.  3 user2 user2     78 11月 13 20:43 user2

chomd 2770 net ------------>>SGID: 2 modify special permissions

If chomd 770 net, user2 has insufficient permissions

Switch user test

[root@localhost home]# su user1
[user1@localhost home]$ cd net
[user1@localhost net]$ touch user01
[user1@localhost net]$ ll
总用量 0
-rw-rw-r--. 1 user1 project 0 11月 13 20:50 user01
[user1@localhost net]$ exit
exit
[root@localhost home]# ll
总用量 4
drwx------. 16 aoian aoian   4096 10月 16 09:50 aoian
drwxrws---.  2 root  project   20 11月 13 20:50 net
drwx------.  5 user1 user1    128 11月 13 20:55 user1
drwx------.  3 user2 user2     78 11月 13 20:43 user2
[root@localhost home]# su user2
[user2@localhost home]$ cd net
[user2@localhost net]$ ls
user01
[user2@localhost net]$ exit
exit

New user3 test

[root@localhost home]# useradd user03
[root@localhost home]# su user03
[user03@localhost home]$ ls
aoian  net  user03  user1  user2
[user03@localhost home]$ cd net
bash: cd: net: 权限不够