This article will give you a detailed introduction to commonly used Linux commands, demonstrations and some basic knowledge
Directory
ls command
file command
pwd command
whoami command
cd command
Relative path and absolute path
which directive
touch command
mkdir command
Add user trust relationship
rmdir command
rm command
man command
cp command
mv command
edit
cat command
echo command
Redirect
more command
less command
head command
tail command
Pipeline operation
date command
cal command
find command
grep command
zip command/unzip command
tar command
bc command
uname command
shutdown command
stat command
Three times under Linux
touch command supplement
Hotkeys in Linux-
List of commands
ls command
Syntax: ls [options] [directory]
Function: ls has multiple options. For a directory, this command lists all subdirectories and files in the directory. For files, the file name and other information will be listed
ls without options defaults to displaying files in the current directory
Options:
-l : List file details in the form of a list
In the Linux system, the file type is not distinguished by the file suffix, but the file type is identified by the first character, regardless of whether the file suffix is .c or .txt or other suffixes, as long as it starts with -, it is an ordinary file
d: Directory file, simply a folder, we can create a new file under this directory file
-: Ordinary file, divided into text Files, dynamic and static libraries, executable programs, etc.
l: Soft link (similar to Windows shortcut)
b: Block device file (such as hard disk, optical drive, etc.)
p: Pipe file
c: Character device file (such as screen and other serial devices) -
s: Socket file
We focus on the first two types of files today
Ordinary files can be divided into many types. In order to be compatible with windows and make it easier for most of us Linux users to distinguish different files, we are still used to using suffixes to represent different file types. However, some files must be added with a suffix, such as .c files written in C language, which require special processing and use the suffix to distinguish the type
-a: Display all files in the directory including hidden files. The files starting with a dot represent hidden files. One dot represents the current path and two dots represent the upper-level path. We Will be explained in the cd command below. and..
-d: Display the directory like a file, while Files in the directory are not displayed. The dot here represents the current path
-R: List all subdirectories files under (recursively), all files in the directory will be listed
-n: Use numeric UID or GID instead of name
There are some other options that I won’t demonstrate. You can try them if you go down.
-1 Output only one file per line
-r Sort the directory in reverse order
-k to The size of the file in k bytes. ls –alk specifies the file
#-i to output the index information of the i node of the file. For example, ls –ai specifies the file-
-t and sorts it by time
file command
Function: View file type
Syntax: file [file]
[king@VM-12-11-centos ~]$ file cat.txt
cat.txt: UTF-8 Unicode text #类型是文本文件
[king@VM-12-11-centos ~]$ file ret #类型是目录文件
ret: directory
Copy after login
pwd command
Syntax: pwd
Function: Display the current path
whoami command
Function: Display the current user
Two writing methods
cd Command
Function: switch path
Usage: cd [the path you want to switch]
Linux manages files in a multi-tree structure. The files and directories on the disk are composed of a directory tree. Each node is a directory or file. Root directory: /
Relative path and absolute path
When we need to find a file, You must know the path and file name of the file, such as looking for the text.c file, because each node has only one parent node, and the path from the root directory to the text.c file is unique. . The path that completely describes the file location is the absolute path. The absolute path can uniquely identify a file. The pwd command above displays the absolute path
The relative path is: its own path relative to the target location, which is not unique. We can find the file from different locations
Absolute path: The path from the following directory to the specified file, which can uniquely identify a file
Relative path: The path from a certain file to the specified file. It cannot uniquely identify a file.
The cd command can switch paths between relative paths and absolute paths.
You can switch to the specified directory through the absolute path
[king@VM-12-11-centos Linuxclass]$ pwd
/home/king/Linuxclass
[king@VM-12-11-centos Linuxclass]$ cd classcode
[king@VM-12-11-centos classcode]$ ls
a.out ret.txt test test.c
[king@VM-12-11-centos classcode]$ cd test
[king@VM-12-11-centos test]$ cd ../../p1 #切换到上上级目录的p1路径下
[king@VM-12-11-centos p1]$ pwd
/home/king/Linuxclass/p1
[king@VM-12-11-centos Linuxclass]$ which ls
alias ls='ls --color=auto' #alias：给指令取别名
/usr/bin/ls #我们的指令都是系统简化过的
[king@VM-12-11-centos Linuxclass]$ which ll
alias ll='ls -l --color=auto' #ll可以代替ls -l
/usr/bin/ls
[king@VM-12-11-centos Linuxclass]$ which cd #同时我们发现指令都是在bin目录下的
/usr/bin/cd
[ret@VM-12-11-centos ~]$ su
Password: #输入root用户密码
[root@VM-12-11-centos ret]# whoami #切换为root用户
root
[root@VM-12-11-centos ret]# su ret #root用户可以直接切换成指定用户，不需要输入用户密码
[ret@VM-12-11-centos ~]$ whoami #现在我们就切换到用户ret了
ret
[king@VM-12-11-centos file11]$ man 3 printf #我们可以查看printf库函数
Copy after login
cp指令
语法：cp [选项] [源文件] [目标文件] [指定目录]
功能：复制文件或目录
常用选项：
-f 强行复制文件或目录， 不论目的文件或目录是否已经存在
-r 递归处理，将指定目录下的文件与子目录一并处理。
We copy the file file11 and name it file
Copied to the current directory by default, you can also specify the directory at the end
mv command
Function: move files or rename files
Usage:mv [options] [source file] [target file]
Options:
-f: force means force. If the target file already exists, it will be overwritten directly without asking.
-i: If the destination file (destination) already exists, it will ask whether to overwrite it!
Here we move the file file11 to the file directory
If mv is not followed by a file, but filename, the file will be renamed. In addition, when searching for public accounts, Linux should learn how to reply "monkey" in the background and get a surprise gift package.
For example, rename the file file11 to change
cat command
Function: View file content
Syntax: cat [options] [file]
Options:
-b: Number non-empty output lines
-n: Number all output lines
-s: Do not output multiple blank lines
##echo command
Function: Display the string to the standard output, that is, on the screen, echo defaults to newline
Redirect
Can we write the string to a file?
The answer is yes. By redirecting and adding the > symbol and the file name after the string, you can write the string that should be displayed to the standard output into the file. If the file does not exist, just The file will be automatically created. This is output redirection.
writes the string that should be displayed on the screen into the target file. At the same time, output redirection will clear the original content of the file. Re-write
When writing this, the previous hello Linux has been almost cleared
If you want to keep the previous content and write it, It is necessary to append the redirection > symbol to become >> symbol
No file is added after the cat command. By default, the content is read from the keyboard and echoed to the monitor. That is
-i: Ignore upper and lower case, upper and lower cases are treated as the same
-n: Output line number
##-v: Reverse selection
Let’s take the file whose content is 0-1000 lines
cat.txtExample
When we display the file content, we will bring '90' All the characters are displayed
We use output redirection to write two lines into the file, and -i ignores case, so that both lines can be searched out
-r: Process all files and subdirectories in the specified directory together, recursively
unzip Syntax: unzip [compressed file.zip]
-d: Compress to the specified path
If we do not add the -r option, compress the file directly
We take the compressed test file as an example, in which test also has 3 subdirectories file, file22 and file33, the compressed file.zip The size is only 160
After decompression, I found that the test file was an empty directory and did not help us compress all the files
So we need to bring the option -r. After decompression, we found that the size of cur.zip is 774, which is significantly larger than the previous 160
Add option -d to extract cur.zip to the ret file at the specified path
tar command
andzip/unzip is similar, but the decompressed file suffix is .tgz
Function: Complete packaging, compression, and decompression
Options:
-c: Parameter command to create a compressed file (meaning create)
##-x: Parameter command to unzip a compressed file
-t: View the files in tarfile!
-z: Does it also have the attributes of gzip? That is, do I need to use gzip compression?
-j: Does it also have the attributes of bzip2? That is, do I need to use bzip2 compression?
-v: Display files during compression! This is commonly used, but it is not recommended to be used in background execution processes!
-f: Use the file name. Please note that the file name must be followed immediately after f! Don't add any more parameters!
-C: Extract to the specified directory
Usually -czf and -xzf Used in conjunction with compression and decompression, here we also move the compressed file cur.tgz to the test directory for decompression
Here we Specify the path of the compressed file cur.tgz through the -C option, and extract the file to the ret directory
The previous operations are all decompression and compression, while packaging is to package all the files that need to be compressed together. It can be understood that the size of the files does not change after all the files are organized
bc command
Function: It can be understood as a calculator
Display the calculation results directly on the screen,Ctrl cExit
uname command
Function: Get computer and operating system related information
Options:
-a: Output detailed information, in order: kernel name, host name, kernel version number, kernel version, hardware name, processor type, hardware platform type, operating system name
-r: Output the kernel version number
##uname outputs the kernel name by default, and hostname outputs the host name by default. In fact, we only need the -a option
Kernel version number: 3 represents the major version number, 10 represents the minor version number, where the minor version number is an even number: the stable version kernel is an odd number: test Version kernel, the kernel version used by our servers is generally not the latest, but some classic versions that have been used for many years. Brand-new versions need to pass the test of time to prove that the kernel is stable, safe, and efficient before they can be used.
shutdown command
Options:
-h: Stop the system service and shut down immediately
-r: Stop the system service Restart after
- -t second：-t [number of seconds], that is, shut down after a few seconds
Before introducing the touch modification file time, we first introduce a command
stat command
Function: View file details
Usage:stat [file]
stat View test File details
Related information about the file:
File: Display the file name
Size: Display the file size
Blocks: Total number of data blocks used by the file
IO Block: IO block size
regular file: File type (regular file)
Device: Device number
Inode: Inode number
Links: Number of links
Access: File permissions
Gid, Uid: File ownership Gid and Uid
Three times under Linux
Access Time: abbreviated as atime, indicating the last time the file was accessed.
Modify Time: abbreviated as mtime, indicating the time when the file content was last modified
##Change Time : The abbreviation is ctime, which indicates the time when the file attributes were last modified.
atime: When we view the file with cat after a while, stat will send the atime time when we view it again. Changes have occurred. Of course, for kernels after 2.6, the rules for the refresh time of atime have been reset. Atime will not be updated immediately, but the OS will automatically update the time after a certain interval. Because compared to modifying file content and attributes, viewing files is the most frequent. If atime is refreshed frequently, the efficiency will be reduced
For mtime: After we write hell, its three times have changed. The change of mtime will not necessarily affect atime, but ctime may change accordingly because the file is modified. When writing content, it is possible to modify the attributes of the file. For example, the size attribute of the file will be modified when writing data.
ctime: The most recent time when the file attributes were changed, this line indicates The most important thing is the file attributes
## The chgmod command can change the access permissions of the file, which also changes the file attributes
touch command supplement
options:
-a Change atime and ctime
-c or --no-create Do not create any documents.
-d Use the specified date and time instead of the current time to change atime and mtime
-f This parameter will be ignored Processing, only responsible for solving the compatibility issues of the BSD version of the touch command.
-m Change ctime and mtime
-r Set the date and time of the specified document or directory to the same as the reference document or directory The date and time are the same.
-t Use the specified date and time instead of the current time
Commonly used are -d, -a -m, and touch The command modifies all times by default. The touch here is to operate on the created file
Hotkeys in Linux
[Tab]: Command completion, press once or twice, the command starting with wh will be displayed on the screen
[c] : Terminate the current program. For example, if characters are continuously output on the screen and an infinite loop code is written, you can Ctrl cterminate
System security related commands: passwd, su, umask, chgrp, chmod, chown, chattr, sudo ps, who
Other commands: tar, unzip, gunzip, unarj, mtools, man, unendcode, uudecode
The above is the detailed content of Detailed explanation of commonly used Linux commands (worth collecting). For more information, please follow other related articles on the PHP Chinese website!
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
