Linux Practice Notes

Mount: Mount command

Mount/dev/sda2/mnt/server

Cd/mnt/server

You cannot uninstall in the/mnt/server directory, or if you have a program that uses a disk in mount.

Du-s look at the size of the folder

Du-h Mark K or M

Usage of DF Resources

Df-h Mark K or M

Su-Completely switched past

Su didn't switch over completely.

Linux User and Group management

Useradd passwd Userdel groupadd gpasswd Groupdel

Useradd--/etc/passwd--/etc/shadow--/etc/group--/etc/gshadow

Create a/home/shrek at the same time

Then CP to/etc/skel/.*/home/shrek

Chown-r Shrek.shrek/home/shrek

/etc/passwd

Shrek:x:500:501::/home/shrek:/sbin/nologin

Shrek User Name

X: The password is stored in the shadow file.

UID500

501 Groups of ID501

:: In the middle of the colon, put a function description or comment for the user

User home Directory/home/shrek

Shell/sbin/nologin used by the user

/etc/shadow

Shrek:[email Protected]@#$%%#%23425$:13822:0:999999:7:::

Shrek User Name

Passwords that have been encrypted

13822 from January 1, 1970 onwards to how many days now. Linux time

0 The shortest history of password changes, and how long you can change them. 0 to never expire.

99999 expiration time, 99,999 days to expire.

7 How many days before your password expires

:: Password disabled for Linux time

/etc/group

shrek:x:501:

If Todd is added to the group, it can be shrek:x:501:todd directly, other users

Linux users only differentiate between a UID of 0 and a UID of not 0.

/etc/gshadow

Rarely used.

Tail-5/etc/passwd only see the last five lines of passwd.

head-5/etc/passwd View passwd header Five elements file.

Useradd-g root,bin,todd Shrek

Assign Shrek to join multiple groups at the same time.

But if you do it again,

Useradd-g mysql,ttt Shrek

Then Shrek joins only MySQL and TTT because it specifies which group the Shrek belongs to, not the cumulative increment group.

Want to have multiple users join a group

Gpasswd-m SHREK,TODD,TTT Root

Add multiple users (SHREK,TODD,TTT) to the root group

Head/etc/group Verify that there are several users behind the root group.

What if I accidentally put/etc/passwd or/etc/shadow delete?

Single User

ls/etc/passwd

cp/etc/because a single user has a backup file

Man familiar with the properties of the file detailed

Kill the SSH man.

Skill-9 PTS/2 Kill the PTS/3 process of the machine.

W who user

W Use the most

MESG y

Write Root PTS/2

Write a message to write to PTS/2.

Crtl+d keyboard input ends.

Wall the news to everyone. All the people on the machine will suffer. People on each console will receive this message.

To view a user's logon log:

Last

Lastlog the last logon time for each user.

Finger look at the information of a particular user.

This article is from the "Big da Qi" blog, please be sure to keep this source http://newgate.blog.51cto.com/9210093/1558598

Linux Practice Notes