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This article will explain in detail the basic knowledge about the Linux operating system. The editor thinks it is very practical, so I share it for you as a reference. I hope you can get something after reading this article.

1. Introduction to Linux

2. Introduction to Ubuntu

3. File and directory operations

3.1 basic shell operation

3.1.1 Command parser

Essence: call the corresponding executable program according to the name of the command

The type of shell used for viewing: echo $SHELL

3.1.2 commonly used shortcut keys

Use the tab key to complete the main keyboard shortcuts such as command / directory

3.1.3 Linux directory structure

Important directory structure:

/ bin: executable system-level binary commands under the Linux operating system

/ dev: device directory

/ etc: contains information about all configurations of the current operating system user

/ home: home directory

/ lib: the library files used by the operating system and related configurations have been placed in this directory

/ media: the system mounts the directory automatically

/ mnt: manually mounted directory

/ root: home directory of root user

/ usr: unix software resource pack management directory, which stores some things under the current user

3.1.4 user directory

Absolute path and relative path

User directory

Devin: currently logged in user

Ubuntu: hostnam

~: user's home directory (host directory)

$: the current user is an ordinary user

#: superuser

3.1.5 File and directory operations

Tree: displays the current files and directories in a tree

Ls: view all files and directory information under the execution directory

-a view hidden files

-l View details.

Cd: enter the specified path (cd ~ / cd -)

Pwd: show current path

Create / delete directories, files

Cp: copy a file or directory

View the contents of the file

Ln

File and directory properties

Which: view the path where the specified command is located

3.1.6 File permissions / users / user groups

3.1.7 find and retrieve

3.1.8 installation and uninstallation of software

Online installation (preferred)

Deb package installation

Source code installation

3.1.9 disk Management

The system mounts the directory by default: / media

Manually mount the directory: / mnt

Mounting method: mount + device name + mount directory

Uninstall: when unmount is uninstalled, the user's current location must not be in / mnt (/ media) or its subdirectories, otherwise it cannot be uninstalled.

3.2 compressed package Management

Packing

Compress

3.3 process Management

Who: view the status of current online users

Ps: view the status of processes running within the entire system (ps-aux)

Kill: used to terminate the specified process

Env: view current process environment variables

Top: viewing Task Manager

3.4 Network Management

Ifconfig: get network interface information

Ping: test connectivity to the target host

-c: stop after the specified number of packets are sent

-I: set a few seconds interval to send a packet

Nslookup: the IP address corresponding to the domain name of the production server

3.5 user Management

Create a user

Sudo addusr + user name

Sudo useradd-s / bin/bash-g devin-d / home/devin-m devin

Set user group: sudo groupadd devin

Delete a user:

Sudo delusr + user name

The function of sudo usrdel-r itcast:-r is to delete the user's home directory together

Switch user: su + user name

Root user: sudo su

Set password: sudo passwd + user name

Log out login user: exit

4. Common servers

Ftp server

Install the ftp server

Sudo apt-get install vsftpd

Modify the configuration file (/ etc/vsftpd.conf)

Start the process: sudo service vsftpd restart

Data transmission

Problem: 500OOPS: vsftpd: refusing to run with writable root inside chroot ()

Solution: add a line to the configuration file: allow_writeable_chroot=YES

5 、 vim

Vim is a text editor with no menus, only commands, and many commands

There are three modes of vim

Command mode insert mode last line mode

5.1 Command mode

5.1.1 move the cursor

5.1.2 Delete and undo

5.1.3 copy and paste

5.1.4 Visual mode

5.1.5 find and replace

5.1.6 text Line Mobility and Man Page

5.2 insert mode

5.3 Last line mode

5.4 split screen operation

6 、 gcc

Gcc is a compiler. The common parameters are as follows:

-v/--version to check the version number

-O generate target file

-I specify the header file directory

-D define macros at compile time

-On optimization 0 is not optimized, 1 is the default, and 3 is the highest optimization level

7. Production and use of static library

7.1 advantages and disadvantages of static libraries

Advantages:

Convenient addressing and high speed

The library is packaged into an executable program, which can be used by publishing the executable program directly.

Disadvantages:

The code of the static library has been loaded into the executable program during the compilation process, so it is larger.

If the static library changes, the program needs to be recompiled

7.2 making and using static libraries

8. Production and use of dynamic library

8.1 advantages and disadvantages of dynamic libraries

Advantages:

The code of the shared library is loaded into memory when the executable program is running and is only a simple reference during compilation, so the code is small and easy to update (dynamic link).

Disadvantages:

Delayed binding, slightly slower

8.2 production and use of dynamic Library

9. Gdb debugging

This is the end of the basic knowledge about the Linux operating system. I hope the above content can be helpful to you and learn more knowledge. If you think the article is good, you can share it for more people to see.

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