A: user
1, create user test01, test01 user will generate a directory in / home / below
useradd test01
ssh test01 @ ip login prompt must have a password
2, change the password
passwd test01 (Enter password)
passwd (enter, change the root password)
3, view the user information
id username
4, delete users
userdel username
4, additional user group information (user test01 group added to testshare)
usermod -a -G testshare test01
II: group
1. Create group
groupadd group
2. Delete Group
groupdel group
Three: directory permissions
1. Create a directory testshare
mkdir testshare
2, view directory permissions
ll testshare
drwxr-xr-x (1, first letter is represented by: d directory - file 2, rwx (read, write operation right), 3, 3 represents the front of the rights holder, intermediate representation is holding group permissions, the last three represent other people's rights)
x; the ability to execute the file (usually executable file)
x: directory permissions to enter the directory
3, change the directory to hold user group information
chowd user: group directory: Change directory owner, holds group information, the holder of the situation did not write the original default user
chown: Test hare testsare
4, modify the directory permissions (character mode)
chmod a (All) U (User) g (group) o (others) + (increase) / - (decrease) rwx (permission) testsare
chmod g + w testsare (testsare group permissions w increases)
chmod o-rx testsare (testsare other minus rx permission)
6, modify the directory permissions (numerically)
1 1 1 (binary 0011, 0102, 0113 and so on) (100: 4, 010: 2, 001: 1)
r w x