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)