Linux quick start knowledge summary

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1. Command line shortcut keys

• Ctrl+a: move the cursor to the beginning
• Ctrl+e: move the cursor to the end
• Ctrl+u: Clear the entire line

2. File operation instructions

• cd ...: jump to the parent directory
• ls : view
• pwd : view the current directory

1. Important documents

• "Everything you see is a file" in LInux system
• bin: store binary executable files
• boot: Store the boot program
• dev: store device files
• home: store users
• etc: user information and system configuration files
• lib: library file
• root: administrator host directory (home directory)
• usr: user resource management directory

2. File type

• Normal file:-
• directory file: d
• Character device file: c
• Block device file: b
• Soft link: l
• Pipeline file: p
• socket: s
• unknown file

3.cp copy instruction

Copy files:

	cp file1 file2
	cp file1 dirl
	cp file1 ../

Copy directory:

	cp dir1 dir2 -r
	cp dir1 ~l -r

4. Increase permissions

	chmod u+x 文件名

5. Modify the operating instructions

Create user:

	sudo adduser 新用户名

Modify the user who owns the file:

	sudo chown 新用户名待修改文件。
	sudo chown wangwu a. c

delete users:

	sudo deluser 用户名

Create user group:

	sudo addgroup 新组名

Modify the user group to which the file belongs:

	sudo chgrp 新用户组名待修改文件。
	sudo chgrp g88 a.c

Delete group:

	sudo delgroup 用户组名

3. Find and Retrieve

find command: find files

-type按文件类型搜索d/p/s/c/b/1/ f:文件
-name按文件名搜索
	find ./ -name"*fi1e*.jpg"
-Imaxdepth指定搜索深度。应作为第一个参数出现
	find ./ -maxdepth 1 -name "*fi1e*.jpg'
-size按文件大小搜索．单位:k、M、G
	find /homelitcast -size +20M -size -50M
-atinme、 mtime、ctime 天  anin、rin、cmin分钟

exec: Execute the result set found by find

find/usr/ -name '*tmp*' -exec ls -ld {} \;
-ok:以交互式的方式将find搜索的结果集执行某一指定命令
-xargs:将find搜索的结果集执行某一指定命令。当结果集数量过大时，可以分片映射
	find /usr/ -name '*tmp*’l xargs 1s -1d l

grep command: find file content

grep -r 'copy' ./ -n
ps aux | grep 'cupsd'’--检索进程结果集。

4. Installation

1. Original code installation

• Unzip the source code package
• cd you
• ./configure
  detects whether the file is missing, creates a Makefile, and detects the compilation environment
• make
  compiles source code, generates libraries and executable programs
• sudo make install
  installs libraries and executable programs into the system path
• sudo make distclean
  remove and uninstall software

2. Software installation:

• 1. networking
• 2. Update the software resource list to the local. sudo apt-get update
• 3. Install sudo apt-get install software name
• 4. Uninstall sudo apt-get remove software name
• 5. Install using a package (.deb): sudo dpkg -i install-package-name

5. Compression and decompression

tar compression:

• 1.tar -zcvf The name of the compressed package to be generated to compress the material.
  tar zcvftest.tar. gzfile1 dir2 use _gzip compression.
  tar jcvftest.tar.gz fi1e1 dir2 Use bzip anti-style compression.

tar decompression:

• 
  Use gzip to decompress the c --> x tar zxvftest.tar.gz in the compression command .
  tar jxvftest.tar.gz uses bzip2 to decompress.

rar compression:

• rar a -r compressed package name (with .rar suffix) compressed material.
  rar a -r testrar.rar
  stdio.h test2.mp3

rar decompression:

• urrar x package name (with .rar suffix)

zip compression:

• zip -r Compression package name (with .zip suffix) to compress the material.
  zip -r testzip.zip dir
  stdio.h test2.mp3

zip decompression:

• unzip compressed package name (with .zip suffix)

6. Three working methods of vim

Jump to the specified line:

• 88G (command mode)
• :88 (last line mode)

Pick the beginning of the line:

• gg (command mode)

Looking at the end of the line:

• G (command mode)

Auto formatter:

• gg=G (command mode)

Braces correspond to;

• % (command mode)

Move the cursor to the beginning of the line:

• 0 (command mode) execution ends, and the working mode remains unchanged.

Move the cursor to the end of the line:

• $(command mode) execution ends, and the working mode remains unchanged.

Delete a single character:

• The execution of x (command mode) ends, and the working mode remains unchanged.

Delete a word:

• dw (command mode) place the cursor on the first letter of the word to operate.

Delete from cursor to end of line:

• D or $ (command mode)

Delete the cursor to the beginning of the line:

• d0

Delete specified area:

• Press V (command mode) to switch to "visual mode", use hjk1 to move the cursor to select the area to be deleted. Press d to delete the data in this area.

Delete specified 1 line:

• On the line where the cursor is located, press dd (command mode)

Delete specified N lines:

• Delete the first line at the cursor, press Ndd (command mode)

Copy a line:

• yy

Paste:

• p: backward, P: forward.

Find:

• 1. Find the content of the idea:
  In the command mode, press "!" to input the keyword you want to search, and press Enter. Use n to retrieve the next one.
• 2. Find what you see:
  In the command mode, place the cursor on any character of the word, press "*" "#"

One-line replacement:

• Put the cursor on the line to be replaced, enter the last line mode, enter: s /original data/new data

Replacement throughout:

• Last line mode,: %s/Original data/New data/gg: Not added, only the first one of each line will be replaced.

Replacement of specified lines:

• Last line mode,: start line number, end line number s / original data / new data / gg: do not add, only replace the first one of each line.
  :29,35s /printf/print1n/g

Revocation, anti-revocation:

• u, ctr1tr (command mode)

Split Screen:

• sp: Horizontal screen. Ctrl1+ww switch. vsp: vertical screen. Ctrl1+ww switch.

Jump to the man page:

• Put the cursor on the word of the function to be viewed, and use K (command mode) to jump. specified volume, nK

View macro definition:

• Put the cursor on the macro definition word to be viewed, and use [d to view the definition statement.

Execute the she11 command in the last line mode:

• :!Order
• : ! 1s -l

7. Four steps of gcc compilation

gcc compilation 4 steps:

• -I: Specify the directory location where the header file is located.
• -c: Only do preprocessing, compilation, and assembly. get the binaries!!!
• -g: Add debug statements when compiling. Mainly supports gdb debugging.
• -wall: Display all warning messages.
• -D: Register macro definitions "dynamically" with the program.

8. Static library and dynamic library

Static library production and use steps:

1.将 .c生成.o文件
	gcc -c add. c -o add. o
2．使用ar工具制作静态库
	ar rcs lib库名.aadd.o sub. o
3．编译静态库到可执行文件中:
	gcc test.c lib厍名.a -o a. out

Header guards: prevent header files from being included repeatedly

#ifndef _HEAD_H
#define _HAD_H
...
#endif

Dynamic library production and use:

1.将.c生成.o文件，(生成与位置无关的代码–fPIC)
	gcc -c add. c -o add. o -fPIC
2．使用gcc -shared制作动态库
	gcc -shared lib库名.soadd.o sub.o div.o
3．编译可执行程序时，指定所使用的动态库。-l:指定库名-L:指定库路径。
	gcc test.c -o a.out -lnmymath -L./lib
4．运行可以执行程序./a.out
	原因:
		链接器:工作于链接阶段，工作时需要-l和-L
		动态链接器:工作于程序运行阶段，工作时需要提供动态库所在目录位置。
				  通过环境变量:export LD_LIBRARY_PATH=动态库路径
				  ./ a.out成功! !!(临时生效，终端重启环境变量失效)
				  永久生效:写入终端配置文件。 .bashrc
						1) vi ~l .bashrc
						2)写入export LD_LIBRARY_PATH=动态库路径保存
						3) . .bashrc/ source .bashrc / 重启 终端--->让修改后的.bashrc生效
						4) ./a.out成功!