Linux commands from entry to actual combat ---- file directory class

Written in the front: The article explains the commands related to Linux file operations

Shell can be regarded as a command interpreter, which provides us with an interactive text control interface. We can enter commands through the console, which will be interpreted by sell and finally handed over to the kernel for execution. Similar to python's interactive window, that is, the output is the output, and each step of the command will be executed immediately and the result will be returned.

pwd displays the absolute path of the current working path

Full name: print working directoryPrint the absolute path of the working directory
Usage:pwd

Example: To

expand knowledge:
Absolute path: relative to the path of the root node, which is the only definite path that really exists on the computer
Relative path: relative to the path of the working path, only relative to the file location of a certain directory, the reference directory is different results also different

ls lists the contents of a directory

Full name: list List directory contents
Usage: ls [option] [directory file]

options	effect
-a	show all files
-l	Show more detailed file information ls -lShort formll

There are some other options,

Example:

options can be used at the same time to

view the structure under the specified directory

Expand knowledge:
the .folder starting with is the hidden folder
..'s upper level directory (cd command will be used)
.the current directory

cd switch directory

Full name: Change directory Switch working path
Usage:cd [参数]

Order	effect
cd absolute path/relative path	Switch the path according to the given path
cd ..	Return to the previous directory of the current directory
cd -	Return to the previous directory
cd	Return to the user's home directory
cd .	Current directory

Example:

mkdir creates a new directory

Full name: make directory Create a new directory
Usage: mkdir [option] The name of the directory to be created

options	effect
-p	Create multi-level directories

Example:
create a directory, create a multi-level directory

delete an empty directory

Full name: remove directory to delete an empty directory
Usage: rmdir the directory to be deleted

options	effect
-p	Delete multi-level directories

Example:
Delete the fish1 and fish2 folders created above. Note that this command can only delete empty directories. If the directory is not empty, an error will occur.

Multiple directories can be deleted at the same time, and the directories are separated by spaces.

# 同时删除dir1 dir2
rmdir dir1 dir2

The deletion of multi-level directories can be realized through -pparameters. When deleting a multi-level directory, it can only be deleted when the directory is empty
. Example: To delete aa/bb/cc, first determine whether the cc directory is empty, delete it if it is empty, and then determine whether the bb directory is empty Delete, if it is not empty, exit delete, and then cycle the above operations in turn

touch to create a new file

Full name: touch
Usage: touch The name of the file to be created
Example: create a file in the current directory Create aa.txt aa.txtfile

in the root folder

Expand knowledge:
use vim, vi, you can also create a file,
many commands can be combined >to >>create a file and write content to the file

cp copies files or directories

Full name: copy copy file
usage: cp [option] source dest copy source to dest

options	effect
-r	copy entire folder recursively

sourceSource file/directory
destTarget file/directory
Example:
copy aa.txt to the aa directory

When the last specified file is not a directory but a file, you will be asked to choose whether to overwrite: yoverwrite nor not overwrite, cancel copy

, copy the entire directory folder to another directory

Expand knowledge:
\cp forces overwriting without prompting

rm removes a file or directory

Full name: remove deletes a directory or file
Usage: rm [option] the directory/file to be deleted

options	effect
-r	Recursively delete all contents of a directory
-f	Force delete without prompting
-in	Display the detailed execution process of the command

Example:
Delete an ordinary file

Delete all contents in the directory (the directory will also be deleted)

To expand knowledge:
to delete all files in a directory, you can use
/* * to represent all content

mv moves files and directories, renames files

Full name: move Move files or files with the same name
Usage:

• mv 原文件名 新文件名Rename
• mv 原文件地址 要移动到的地址move folder

Example:
Rename aa.txt to bb.txt and

move the bb.txt file to the root directory. After the move, there will be no local files.

Move and rename

cat to view the contents of the file and create a new file

Full name: concatenate View the contents of the file, starting from the first line
Usage: cat [option] the file to view

options	effect
-n	Display line numbers for all lines, including empty lines
-b	Display line numbers, excluding blank lines
-s	When a blank line with more than two consecutive lines is encountered, it is replaced with a blank line of one line.

Example:

View file content

Create a file and write data

Append content to the end of the file

Expand knowledge:
cat can view files, create files, clear files, and append file content
cat is usually used to view files with small content and not much content

View the content of more files in split screen

Full name: more A text filter based on the vi editor, which displays the contents of the file page by page in a full-screen manner
Usage: more The file to be viewed

operate	effect
space	page down
Enter	next row
b	page up
q	quit more
=	Output the line number of the bottom line on the screen
:f	output filename and current line number
Ctrl +F	scroll down one screen
Ctrl +B	scroll up one screen

Example:

less split screen display file content

Full name: less is very similar to more, and its function is more powerful than more. When less loads files, it does not load them all at once, but loads them as needed.
Usage: less To view files
Example:

operate	effect
space	page down
Enter	next row
b	page up
q	quit more
G	jump to end
g	jump to beginning
/keyword	Find keywords n down, N up
=	Output the line number of the bottom line on the screen
:f	output filename and current line number
Ctrl +F	scroll down one screen
Ctrl +B	scroll up one screen

Expand knowledge:
For large files, using less is more efficient than using more.

echo output content

Full name: echo output content to the console
Usage: echo [option] [output content]

options	effect
-and	support for escape characters

Example:

View system variables

Output system PATH

Write environment variables to a file

Expand knowledge:
With cooperation > >>, the output content can be written into the file, and the file can be created if the file does not exist

head Display the header information of the file

Full name: head is used to display the content at the beginning of the file, and the first 10 lines are displayed by default
Usage: head [option] file displays the first few lines of the file

options	effect
-n number	Specify the number of lines to display the header of the file

Example:
display the first 10 lines and the first 3 lines of the file

tail output file tail content

Full name: tail Display the content at the end of the file, the last 10 lines at the end of the default file
Usage: tail [option] file

options	effect
-n number	Specifies the number of lines to display at the end of the file
-f	Track all updates to this document in real time

Example:
Output the last 10 lines and the last 4 lines of the file

Expand knowledge:
tail -f 文件It is suitable for monitoring log files, it will not exit after execution, and it will always monitor changes in content

> output redirection and >> append

Need to be used in conjunction with other commands

operate	effect
ls -l > file	Write the output content to the specified file, create the file if the file does not exist, overwrite the file if the file exists
ls -al >> file	Append the output to the end of the file
cat file1 > file2	Overwrite the contents of file 1 to file 2
echo content >> file	Append the output to the specified file
…	…

Anything that can be output to the console can be used > >>to write the content into
the file. There are many corresponding operations

ln soft link

ln: link
soft links are also called symbolic links, similar to shortcuts in windows

Basic syntax
ln -s 原文件或目录 软链接名Create a soft link to the original file

delete soft link

rm -rf 软链接名Do not use rm -rf 软链接名/this means that the content of the original file is deleted

Example
Create a soft link

The instructions on Linux file operations are here. The article only explains some of the most common commands and options during use, which is enough for daily operations. If there are mistakes in the article, you are welcome to point them out