Linux Basic command and file management

• Linux Terminal Introduction
• Shell prompt
• Bash Shell Basic Syntax
• use of BASIC commands:ls, pwd, CD
• View System and BIOS Hardware Time
• How Linux gets Help
• Linux shutdown command: Shutdow, INIT, etc.
• Linux 7 Boot levels
• Create a quick and easy snapshot of your experimental environment
• Set up the server to automatically power on after the call

Linux Terminal Introduction

TTY Console terminal pts Virtual Terminal

Tty1-tty6

The first entry is the graphical surface:tty1 is the graphical interface.

the graphical interface switches to Character Interface Terminal: ctrl+shift+alt+f2-6

to switch characters to the graphical interface: Alt+f1

PTS Virtual Terminal

Ctrl+shift+t

Alt+1

Zoom in:Ctrl+Shift+ +

Zoom Out:Ctrl +-

pts (pseudo-terminal slave) pseudo terminal : after connecting via the SSH related tool, the terminal is shown as: Pts

Shell prompt:

[email protected] ~]#   

[user @ host name current directory name] prompt root # Normal User: $

Bash Shell Basic Syntax

Summary Linux command input rule:

How to enter a command:

Command [Options] ([parameters]) [Value of options] ([value of parameter])

Space as a split

common Options (parameters):-H--help; Features: Options look like:-Letters OR--add words

Basic command:

ls Command

function: See what files are in the current directory

syntax:ls directory, if you do not add a directory to view the current directory

Parameters:

-L display the shortcut in the detailed information system #ll

-A Show hidden files

-D View directory (without viewing the contents)

-H Enhanced Readability

Early Linux is a bit by bit.

Cases:

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

-rw-r--r--1 root root 1753 Jan 20:45/etc/passwd

[Email protected] ~]# LS/ETC/PASSWD

/etc/passwd

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

/etc/

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

Drwxr-xr-x. 20:45/etc/Root 12288 Jan

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

-rw-r--r--1 root root 1753 Jan 20:45/etc/passwd

[Email protected] ~]# LS-LH/ETC/PASSWD

-rw-r--r--1 root root 1.8K Jan 20:45/etc/passwd

Example: viewing hidden files,

Ls-a

. Current directory

.. Parent directory (upper directory, parent directory)

Pwd

Function: View current directory

syntax:pwd has no parameters

Cases:

Pwd

[Email protected] ~]# ll-d/etc/

Drwxr-xr-x. 20:45/etc/Root 12288 Jan

Cd

Role: Switch Directories

Syntax:CD directory Name

Cases:

#cd back to the user's own home directory

#cd ~ Go back to the user's own home directory

#cd-Go back to the previous directory

# cd/etc////sysconfig/ the same as Cd/etc/sysconfig .

cd/etc/ the Same as cd/etc .

View System and BIOS hardware time: Refers to the BIOS time

[Email protected] sysconfig]# Hwclock

Wed 08:58:11 PM CST-0.942319 seconds

How Linux gets Help

method 1: Add parameter-H or--help

[email protected] ~]# shutdown --help

[Email protected] ~]# fdisk-h

[email protected] ~]# Mans Find

Shutdown command:

shutdown , Init , reboot    

Shutdown

Function: Shutdown, restart, timer shutdown

Syntax: shutdown [Options]

The following options are available:

-R = Restart the computer

- h = off Machine

-H time = timer off

-C-= Cancel the pre-timer shutdown or Ctrl + C

Cases:

shutdown-h +10 #10分钟后关机

If you want to use the command at a specific time when the timer is turned off:

Shutdown-h 10:01

immediate shutdown: shutdown-h now

Shutdow-r usage is the same as shutdown-h.
Shutdown-r now restart
shutdown-r +10   # Restart after 10 minutes
shutdown-r 22:22     # Restart after 22:22

Init Command

Role: Switching the system operating level

syntax:init 0-6

Cases:

Init 0 command is used to immediately switch the system run level to 0 , that is, shut down the machine;

Init 6 command to switch the system run level to 6 , that is, restart.

Linux 7 Boot levels:

0 System shutdown mode, the system default operation level cannot be set to 0, otherwise it will not start normally, the machine shuts down.
1 single-user mode, root privilege, for system maintenance, prohibit remote login, like Safe mode login under Windows.
2 Multi-user mode, no NFS network support.
3 full multi-user text mode with NFS, login to console command line mode.
4 The system is unused, reserved for general use, and in some special cases it can be used to do something. For example, you can switch to this mode to do some setup when your laptop's battery is running out.
5 graphical mode, after landing into the graphical GUI mode, X window System.
6 Restart mode, the default run level cannot be set to 6, otherwise it will not start normally. Running the init 6 machine will restart.

RunLevel

Function: View the current level of operation

Syntax:runlevel

• Create a quick and easy snapshot of your experimental environment

Configure a good static IP address, close iptables firewall, turn off SELinux

[[Email protected] ~]# Setup

[[email protected] ~]#/etc/init.d/networkmanager stop

Stopping NetworkManager daemon: [FAILED]

[Email protected] ~]# Chkconfig NetworkManager off

[Email protected] ~]#/etc/init.d/network restart

[email protected] ~]# cat!$

Cat/etc/selinux/config

# This file controls the state of the SELinux on the system.

# selinux= can take one of these three values:

# Enforcing-selinux security policy is enforced.

# Permissive-selinux Prints warnings instead of enforcing.

# disabled-no SELinux policy is loaded.

Selinux=disabled

#SELINUX =enforcing

# selinuxtype= can take one of these the values:

# targeted-targeted processes is protected,

# Mls-multi level Security protection.

selinuxtype=targeted

[Email protected] ~]# iptables-f

[Email protected] ~]#/etc/init.d/iptables Save

iptables:saving firewall rules to/etc/sysconfig/iptables:[OK]

• Set up the server to automatically power on after the call

Linux Basic file Management

What this section says:

• Linux system directory structure
• relative /absolute path
• Create /copy/delete files
• RM-RF/accident
• View File Contents
• Recovery Linux files that have been deleted

Linux system directory structure

Inverted tree-type structure

/ commonly referred to as the root partition. All files and directories begin with this. Only The root user has write access to this directory.

The---/etc configuration file contains the configuration files for all applications and also contains scripts to start and close a particular program, for example,

/etc/passwd , /etc/init.d/network and so on.

---/boot stores the files that the Linux system needs to load when it starts. (usually saved in another disk partition) Kernel, grub and other files are stored here.

---/home general user all data stored in this directory

---/var is an extensible directory that contains very often variable files. For example,/var/log (System log),/var/lib (Pack documentation),

---/root all data for the administrator. Root User's home directory

---/tmp temporary file storage location

---/usr usr represents the Unix software source

---/bin command This directory contains a binary executable file.

---/sbin system commands, the commands in this directory are intended primarily for system administrators to use for system maintenance. For example, Iptables, reboot, Fdisk, and so on.

/MNT-mount the directory mount point, which the system administrator can use to temporarily mount the file system.

---/dev contains device files. In Linux, everything is considered a file. Terminal devices, USB, disks, and so on are all considered files, such as/DEV/SDA.

absolute path /relative path:

cd/etc/sysconfig/network-scripts/

Relative path:

[Email protected] ~]# cd/etc

[Email protected] etc]# CD sysconfig/network-scripts/

. Represents the current directory

.. Indicates a parent directory

Create /view/copy/delete files and folders

Creating files and folders

Touch

Function: Often used to create empty files

syntax: Touch file name

[email protected]/]# Touch a.txt

[[email protected]/]# ls a.txt

A.txt

Mkdir

Role: Create a directory

syntax:mkdir directory Name

Example: mkdir/tmp/test

-P is created along with the parent directory

#mkdir/path/to/dirname

#mkdir-P

/a/b/c/d

Example 1:

[Email protected] ~]# mkdir-p/A/B/C/D

[[Email protected] ~]# CD !$ #!$ represents the last parameter of the previous command

cd/a/b/c/d

[Email protected] d]# CD. /.. /

[Email protected] b]# pwd

/a/b

To view file methods:

Cat

Function: View the contents of a file

syntax:cat file name

Cases:

cat/etc/passwd

More View file names

Cases:

more/etc/passwd

Q exit

Less view file names

Q exit

Use the cursor keys to page UP

The difference between more and less in Linux

MORE: Does not support back, but almost no need to add parameters, the space bar is the page down, the ENTER key is down the line, in the case of no need to back the situation is convenient.

Less: Supports rollover, either up (PageUp button) or down (pagedown button). , the SPACEBAR is a page down, and the ENTER key is a downward-turning line

Head starts at the first line, viewing the file, showing the first 10 rows by default

-N numbers show how many rows

Cases:

head/etc/passwd

Head-n 3/etc/passwd

Tail starting from the first line, viewing the file, showing the last 10 rows by default

-N shows how many rows

-F Dynamic Display data (not closed) often used to view logs

[Email protected] tmp]# tail-f/var/log/messages

[Email protected] ~]# service network restart

See who modified the /etc/resolv.conf the DNS server address in the .

To copy a file:

Cp

Role: Copying files

Syntax:CP source File Destination file

[Email protected] ~]# cp/etc/passwd/tmp/

[Email protected] ~]# LS/TMP/PASSWD

/tmp/passwd

Copy directory:

[Email protected] ~]# cp/etc//tmp/

cp:omitting (Ignore) directory '/etc/'

-R contains subdirectories and files.

[Email protected] ~]# cp-r/etc//tmp/

CTRL + C

Interaction:

Touch/tmp/test11

Mkdir/tmp/test11 #这个命令还可以创建成功吗?

Note: Files and filenames are different in the same directory.

Delete files and folders

RM  

Action: Delete a file or directory

syntax: rm-rf file or directory name

[Email protected] ~]# rm-rf/tmp/test

[Email protected] ~]# rm-rf/tmp/test11

-R Recursive Delete (can delete things in directory and directory)

-F forcibly removed

Rename:

MV   

Role: Renaming

syntax:MV Source: File or directory name destination: file or directory name

[Email protected] ~]# mkdir Yanhuo

[Email protected] ~]# MV Yanhuo Xiaoli

[[email protected] ~]# ls Yanhuo

Working experience: Use the Delete command carefully, use the MV command frequently

Linux Basic command and file management