Introduction to basic commands under Linux (vi)

I. Rights Management

1. Three types of users:

U: Owner

G: Genus Group

O: Other users

A: All Users

2.chown---Modify the owner of the file

Usage: Chown User name File name or directory name ..., modify directory by default only to change the owner of the directory

-R: Recursively modifies the owner of the file under the directory

--reference=/path/to/somefile file,... Refer to the owner of a file, modify the latter to be the same

Chown username:groupname File,.... Modify the owning group at the same time

- R: Recursively modifies the owning group of the file under the directory

3.CHGRP---Modify the owning group of a file

Usage: CHGRP group name file name or directory name ..., modify directory by default only the group that belongs to the directory

-R: Recursively modifies the owning group of files under the directory

--reference=/path/to/somefile file,... Refer to the group to which the file belongs, modifying the same

4.chmod---Permissions to modify files

Usage: chmod permission value file name or directory name ..., if the number of digits but the previous complement 0

-r: Permission to modify files in directory recursively

--reference=/path/to/somefile file,... Refer to the permissions of a file, modify the latter to the same

chmod u+r File: Add Read permissions for the file owner

chmod u-x File: Remove Execute permissions for file owner

chmod u=rx files: Giving read and Execute permissions to files

chmod ug=rw file: Give read and Execute permissions to file owner and owning group

chmod u=x,g=r File: Grant execute permission to the owner of the file, assign permissions to the owning group

chmod 777 Files: Modify the owner of the file, the group that belongs to, the other person's permissions

chmod +x File: Add Execute permission for three types of files user a omitted

Practice:

1, create a new user without home directory OpenStack;

# useradd-m OpenStack

2, copy/etc/skel for/home/openstack;

# Cp-r/etc/skel/home/openstack

3, change/home/openstack and its internal documents belong to the main group are openstack;

# Chown-r/openstack:openstack/home/openstack

4,/home/openstack and its internal files, group and other users do not have any access rights

# chmod-r go=/home/openstack

Issue: How to add a user manually by adding a user Luochen Basic group Luochen (GID 1000) additional group test without the Useradd command

1. Add a line to the end of the/etc/group file

luochen:x:1000:

Add Luochen to the last field in the test group

2. Add a line to the end of the/etc/passwd file

Luochen:x:1000:1000:luochen:/home/luochen:/bin/bash

3. Add a line to the end of the/etc/shadow file

luochen:!! : 16539:0:99999:7:::

4. Copy home Directory

Cp-r/etc/skel/home/luoche

5. Specify the group to which the file and directory owner belongs

Chown-r luochen.luochen/home/luochen/

6. Delete the owning group and other people permissions

Chmod-r go=/home/luochen/

7. Generate a password

OpenSSL passwd-1-salt ' Luocheng '---1 bits using MD5 encryption-salt to encrypt impurities 8 bits

Copy the generated password into the/etc/shadow file

5.umask Command---Matte code

Determines the default permissions when a user creates a file or directory the system automatically adds 1 if you have Execute permissions when you calculate it must not let the file have permission to execute

The current mask code can be viewed directly with umask

Use Umask 0xxx to set mask code

The type of shell that stands in terms of user login:

Log-in Shell:

Normal usually a terminal Login

Su-username

su-l USERNAME

Non-logon Shell:

su USERNAME

Open Command window under graphics terminal

shell scripts that are executed automatically

Bash configuration file:

Global configuration

/etc/profile,/etc/profile.d/*.sh,/ETC/BASHRC

Personal configuration

~/.bash_profile, ~/.BASHRC

File for Profile class:

Setting Environment variables

Run a command or script

Files of the BASHRC class:

Setting Local variables

defining command aliases

How does the login shell read the configuration file?

/etc/profile--/etc/profile.d/*.sh--and ~/.bash_profile--~/.BASHRC--/ETC/BASHRC

How do I configure a file for a non-logon shell?

~/.BASHRC--/ETC/BASRC-/etc/profile.d/*.sh

The full and half switch of the SU command is whether to read the environment configuration of the switching user

Command aliases used across shells

Add alias Cls=clear to the. bashrc file in your home directory to save and log in to use

To display some information when a user logs on, you can write a script in the. bash_profile file

This article is from "Luo Chen's blog" blog, please be sure to keep this source http://luochen2015.blog.51cto.com/9772274/1634856

Introduction to basic commands under Linux (vi)