Linux Beginner's note seven: Linux User management, password and group commands in detail! (Video serial number: 04_1)

Commands to learn in this section:

User Management commands: USERADD,USERDEL,ID,FINGER,USERMOD,CHSH,CHFN,PASSWD,PWCK,

Group Management commands: Groupadd,groupmod,groupdel,gpasswd,newgrp,chage

Skills learned in this section:

User Management commands

Password management commands

Group Management Commands

User Management commands:

Useradd, Userdel, Usermod, passwd, Chsh, CHFN, finger, id, chage

useradd [Options] USERNAME : Add a user (only three files are involved: Passwd,shadow,group)

-u:uid (greater than or equal to 500, non-repeatable by default)

-g:gid (Basic Group) (group must exist beforehand)

-g:gid,... (additional groups) (can have multiple, group prior to existence)

-C "COMMENT": (note information)

-d/path/to/directory: (Specify home directory)

-S Shell (specifies the user's default shell, preferably a shell present in the "/etc/shells" file)

(/etc/shells: Specifies the security shell that is available for the current system)

(See what your SHELL is:echo $SHELL)

-m–k: (Forced to create home directory, and copy files from/etc/skel home directory

-M: Do not create home directory for users, even if /etc/login.defs set user should have home directory we also do not create it for him)

-R: Adding system users

Environment variables:

PATH

Histsize

SHELL

userdel [option] USERNAME: Delete User

-r: Delete User's home directory at the same time

ID: View user's account attribute information

-U: View UID (user ID) of the user

-G: View the user's GID (Base group ID)

-G: View group IDs for all groups (including additional groups and all groups)

-N: (can be used in combination with the above three to display the name)

finger USERNAME: View user account information (not installed by default, installation method:yum install finger)

usermod: Modify user account properties

-U UID: Modifies the user's user ID

-G GID: Modifies the user's base group ID (the base group is pre-existing)

-a-g GID: Changes the user's additional group (without using the-a option, overwriting the previous additional group)

-C: Modify annotation information

-D-M: Specify a new home directory for the user and move all files under the home directory to the new home directory)

(-D: Specify a new home directory for the user, the files used in the previous home directory can no longer be accessed)

-S: Modify the user's shell

-L: Modify the user's login name (is lowercase l)

-e: Define the user's expiration time (when disabled, format "YYYY-MM-DD")

-F: Specifies the user's inactivity time (the time that the password expires and is not disabled)

-L: Lock account

-U: Unlock Account

Chsh: Modifying the user's default shell

CHFN: Modify comment information (can be viewed with finger username and tail-1/etc/passwd)

Password Management commands:

passwd [USERNAME] ( The default is only to modify its own password, only the administrator can specify the user name, to modify the other user's password)

--stdin: read password from standard input (ex: echo "Redhat" | Passwd–stdin user2)

-L: Lock user account (lowercase l)

-N: Minimum password usage period

-X: Maximum password lifetime

-W: Password warning period

-U: Unlock user account

-D: Remove user password

pwck: Checking user account Integrity

Group Management Commands:

Groupadd: creating groups

-G GID: Specify user base Group ID

-R: Added as System group

　　groupmod: Modifying Group Property information

-G GID: Modify user base Group ID

-N GRPNAME: Modify Group name

Groupdel: Deleting a group

gpasswd: Set password for group (newgrp GRPNAME: Temporarily switch base Group to another group, password required)

Newgrp GRPNAME <--> Exit

chage: change user password expiration information. (not familiar with)

-D: Last modification time

-E: Expiration time (0 means immediate expiration, 1 means never expires)

-I: Inactive time (I in uppercase) (number of days after password expiration, locked account)

-L: Lists the user's and password's expiration date (lowercase l)

-M: Minimum period of use

-M: Maximum lifespan

-W: Warning time

Practice:

1, create a user Mandriva, whose ID number is 2002, the basic Group is distro (group ID 3003), the additional group is Linux;

# groupadd-g 3003 distro

# Groupadd Linux

# useradd-u 2002-g distro-g Linux Mandriva

2, create a user fedora, whose full name is Fedora Community, the default shell is tcsh;

# useradd-c "Fedora Community"-s/bin/tcsh Fedora

3, the change Mandriva ID number is 4004, the basic group is Linux, the additional group is distro and fedora;

# usermod-u 4004-g linux-g Distro,fedora Mandriva

4, to Fedora Plus password, and set its minimum password period of 2 days, the longest is 50 days;

# passwd-n 2-x Fedora

5. Change the default shell of Mandriva to/bin/bash;

Usermod-s/bin/bash Mandirva

6, add the system user HBase, and do not allow its login system;

# useradd-r-s/sbin/nologin HBase

Linux Beginner's note seven: Linux User management, password and group commands in detail! (Video serial number: 04_1)