Linux account security Management--useradd, Groupadd, passwd, Chown, chmod tools

Source: Internet
Author: User
Tags readable stdin account security

Groupadd

- g set Group ID number

Example: Groupadd Tomcat

groupadd-g600 Tomcat

Delete Group with Groupdel

Groupdel Tomcat


Useradd

     -c Comment Add a comment   to the new user;
    -d home_dir Specify a name for the main directory (if you do not want to use a login name for the main directory)  
    -e expire_date Specifies the date   for an account to expire in YYYYY-MM-DD format;
    -f inactive _days specify how many days after the account password expires this account is disabled,     

-1 means disable this feature
-G Initial_group The GID or group name of the specified user login group
-G Group ... Specify one or more additional groups to which the user belongs except for the logon group
-K must be used with-m to copy the contents of the/etc/skel directory to the user's home directory
-M create user's home directory
-M does not create the user's home directory (only used when the default setting is specified for creation)
-N Create a new group with the same name as the user login
-R Create System account
-P passwd Assigning a default password to a user account
s shell Specifies the default login shell
-U UID assigns a unique UID to the account

Example: Useradd-g tomcat-d/var/servlet/service-s/sbin/nologin Tomcat

Delete User with Userdel

Userdel Tomcat

Userdel-r Tomcat home Directory deleted together


passwd

-L Lock User

--stdin reading a password from a file or pipe

-U Unlock User

-D Quick Erase password

Example: passwd Tomcat modifying the Tomcat password

Passwd-l Tomcat Lock User

Passwd-u Tomcat Unlock User

passwd-d Tomcat Clear User password

echo "123456" |PASSWD--stdin Tomcat set Tomcat password to 123456


Usermod Modifying account information

-c< Notes > Modify the Notes text for the user account.

-D Login Directory > Modify user login directory.
-e< Expiration date > Modify the expiration date of the account.
-f< Buffer days > Modify the number of days after the password expires to close the account.
-g< Group > Modify the group to which the user belongs.
-g< Group > Modify the additional groups to which the user belongs.
-l< Account name > Modify user account name.
-L LOCKS the user password to invalidate the password.
-s<shell> modifies the shell used by the user when they log in.
-u<uid> Modify the User ID.
-U unlocks the password.

Instance:


USERMOD-G staff NewUser add NewUser to the group staff

Usermod-l newuser newuser1 Modified newuser1 user name is NewUser

Usermod-l NewUser Lock Account NewUser

Usermod-u NewUser Unlock the NewUser


chmod modifying file directory Permissions

Chmod can use numbers to represent permissions such as chmod 777 file
The syntax is: chmod ABC file
Each of the a,b,c is a number that represents user, group, and other permissions for different users and groups.
R=4,w=2,x=1

R is read permission, W is write permission, X is execute permission


4+2+1=7 to rwx property; readable writable executable
rw-property is 4+2=6; readable writable non-executable
To r-x the property, 4+1=5. Readable executable not writable


Chown modifying the owner and group of files and directories

Chown User1:tomcat/home/test

Chown user2:tomcat/home/test/-R recursive subdirectory modified together (-R)



This article is from the "Practical Linux knowledge and Skills sharing" blog, please be sure to keep this source http://superleedo.blog.51cto.com/12164670/1886432

Linux account security Management--useradd, Groupadd, passwd, Chown, chmod tools

Related Article

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.