Linux user and file directory management

Linux User and Rights management

User Management

Multi-user multitasking operating system

User type

Administrator user root

Normal User

System User/program user

User-related files:

/etc/passwd User Information

Format:

User name: X:uid:gid: Description Information: SHELL

Uid:

---60000

0---999 system users

SHELL:

/bin/bash Default

/sbin/nologin System users

/etc/shadow User password information

User:

Basic Group

Additional group user UserA-----> user Group UserA; Caiwu, Shichang, Jishu, YANFA

1. Create user

# useradd [option] User name

Option options:

1)-U uid Specifies the UID of the user

[Email protected] ~]# useradd-u user2

[[email protected] ~]# ID user2

uid=2000 (User2) gid=2000 (user2) group =2000 (User2)

[Email protected] ~]#

2) Specify the user's base group, additional group

-G Gid/Group name

-G Gid/Group name,...

[Email protected] ~]# Groupadd Caiwu

[Email protected] ~]# useradd-g user1-g Caiwu User3

[Email protected] ~]#

[[email protected] ~]# ID User3

uid=2001 (User3) gid=1001 (user1) group =1001 (User1), 2001 (CAIWU)

3) Specify the user shell name

-S shell name

- m does not create a host directory

[Email protected] ~]# useradd-s/sbin/nologin-m Apache

4) Create a system user

-R

[[email protected] ~]# useradd-r MySQL

5) Specify the user's host directory

[Email protected] ~]# useradd-d/tmp/hadoop Hadoop

2. Switch users

# Su-User name

3. View User ID Information

[[email protected] ~]# ID user1

uid=1001 (user1) gid=1001 (user1) group =1001 (user1)

[[email protected] ~]# ID User3

uid=2001 (User3) gid=1001 (user1) group =1001 (User1), 2001 (CAIWU)

[Email protected] ~]# id-u User3

2001

[Email protected] ~]# id-g User3

1001

[Email protected] ~]# id-g User3

1001 2001

[Email protected] ~]# id-u-N user3

User3

[Email protected] ~]# id-g-N user3

User1

[Email protected] ~]# id-g-N user3

User1 Caiwu

[Email protected] ~]#

4. Set User password

# passwd [option] [user name]

[Email protected] ~]# passwd user1

1) View User password status

[Email protected] ~]# Passwd-s user1

User1 PS 2017-04-11 0 99999 7-1 (password is set, use the SHA512 algorithm.) )

2) lock user password (cannot log in)

[Email protected] ~]# Passwd-l user1

Locks the password of the user user1.

PASSWD: Successful operation

[Email protected] ~]# Passwd-s user1

User1 LK 2017-04-11 0 99999 7-1 (password has been locked.) )

3) Unlock user password

[Email protected] ~]# Passwd-u user1

Unlocks the user User1 password.

PASSWD: Successful operation

[Email protected] ~]# Passwd-s user1

User1 PS 2017-04-11 0 99999 7-1 (password is set, use the SHA512 algorithm.) )

[Email protected] ~]#

4) Force user password to expire

[Email protected] ~]# PASSWD-E user1

The user User1 password is being terminated.

PASSWD: Successful operation

5. Modify user Information

# usermod [option] User name

-U UID

-G Group Name

-Group G Name

-S shell name

[Email protected] ~]# Usermod-ag Caiwu User3

[[email protected] ~]# ID User3

uid=2001 (User3) gid=1001 (user1) group =1001 (User1), 2001 (Caiwu), 2004 (Shichang)

6. Delete users

# userdel [option] User name

[Email protected] ~]# Userdel user1

[[email protected] ~]# userdel-r user2>>> Delete the user's host directory at the same time

User Group Management

1. Create a user group

# Groupadd User Group name

2. Delete user groups

# Groupdel User Group name

[Email protected] ~]# Groupadd Jishu

[Email protected] ~]# Useradd Tom

[Email protected] ~]# Useradd Mike

[Email protected] ~]# Useradd Jerry

[Email protected] ~]# usermod-g Jishu Tom

[Email protected] ~]# usermod-g Jishu Jerry

[Email protected] ~]# usermod-g Jishu Mike

[[email protected] ~]# grep "Jishu"/etc/group

Jishu:x:2005:tom,jerry,mike

[Email protected] ~]# gpasswd-d Tom Jishu

Removing user "Tom" from the "Jishu" group

[[email protected] ~]# grep "Jishu"/etc/group

Jishu:x:2005:jerry,mike

[Email protected] ~]#

User Action Environment Profile:

Copied from the/etc/skel directory

[Email protected] ~]# ls-a/home/usera/

.  .. . bash_logout. Bash_profile. BASHRC. Mozilla

. BASHRC Open a new terminal/ETC/BASHRC

. bash_profile User Login system /etc/profile

. bash_logout Logoff system

Example: Setting command aliases

# alias Command aliases = ' Command '

To set an alias for a single user:

[Email protected] ~]# VIM/HOME/USERA/.BASHRC

Alias ipshow= ' Cat/etc/sysconfig/network-scripts/ifcfg-eth0 '

[Email protected] ~]# SOURCE/HOME/USERA/.BASHRC

To set aliases for all users:

[Email protected] ~]# VIM/ETC/BASHRC

Alias ipshow= ' Cat/etc/sysconfig/network-scripts/ifcfg-eth0 '

[Email protected] ~]# SOURCE/ETC/BASHRC

File directory Permissions Management

General permissions:

RRead 4

WWrite write 2

XExecute execution 1

File:

R viewing file contents (CAT/MORE/LESS/HEAD/TAIL/GREP)

W Edit file contents (VIM)

XShell/python Script

Directory:

R View files under the directory (LS/TMP)

W Modify the files in the directory (new, delete, MV)

x Switch directory (CD)

View File Permissions

[Email protected] ~]# ls-l/etc/fstab

-rw-r--r--. 1 root root 465 July 2016/etc/fstab

View Directory Permissions

[Email protected] ~]# ls-ld/etc/

Drwxr-xr-x. 136 root root 8192 April 13:48/etc/

Set file directory Permissions

1) chmod Modify Permissions

# chmod {augo}{+-=}{rwx} file name

A All

uuser owner

GGroup of genera

o Other

[Email protected] ~]# chmod a+x/test/1.txt

[Email protected] ~]# chmod g=rw/test/3.txt

# chmod nnn File name

[Email protected] ~]# chmod 600/test/4.txt

2) Modify the owner of the file, belong to the group

# chown user name. User group name File name

[Email protected] ~]# chown user1.caiwu/test/1.txt

[Email protected] ~]# chown user1/test/2.txt

[Email protected] ~]# chown root.caiwu/test/4.txt

To modify only the genus group:

# CHGRP user Group name file name

[Email protected] ~]# chgrp caiwu/test/3.txt

Method 2)facl----file access Control List

Set permissions:

Set permissions for individual users

# setfacl-m u: User name: Permission file name

[Email protected] ~]# setfacl-m u:user4:r/test/3.txt

[Email protected] ~]# Getfacl/test/3.txt

Getfacl:removing leading '/' from absolute path names

# File:test/3.txt

# Owner:user1

# Group:user3

user::rw-

user:user4:r--

Group::rwx

Mask::rwx

Other::r-x

Set permissions for a single user group

# setfacl-m G: User group name: Permission file name

Remove Facl Permissions

Remove permissions for a single user

# setfacl-x u: User name File name

[Email protected] ~]# setfacl-x u:user4/test/3.txt

Remove permissions for a single user group

# setfacl-x G: User group name file name

Special permissions:

Suid4

Sgid2

Sticky bit 1# chmod 644 file01 # chmod 6644 file02 # chmod 2700

1, Suid

Role: Ordinary users during the execution of the command, will temporarily obtain the command is the main user of the operating system permissions

[Email protected] ~]# ls-l/usr/bin/passwd

-rwsr-xr-x. 1 root root 27832 June 2014/usr/bin/passwd

Set SUID Permissions

# chmod u+s file name

2, Sgid

For directory settings

Role: After the directory has Sgid permissions, the newly created file in the directory inherits the group information of the directory

Set Sgid Permissions

# chmod G+s Directory Name

[Email protected] ~]# ls-ldh/linux/

Drwxr-sr-x. 2 root Caiwu 18 April 15:37/linux/

3. Sticky bit

For directory settings

Role:

Only the main user, directory owner and root of the file under the directory can delete the file

[Email protected] ~]# ls-ldh/tmp/

DRWXRWXRWT. 8 root root 4.0K April 15:45/tmp/

Set Sticky bit permissions

# chmod o+t Directory Name

chmod, Chown, Chgrp, Setfacl

Common options:-r

This article is from the "lyw666" blog, make sure to keep this source http://lyw666.blog.51cto.com/12823216/1957697

Linux user and file directory management