Preface
I've been dealing with Linux recently, and I feel pretty good. I think the more troublesome thing about Linux than windows is that many things have to be controlled by commands. Of course, this is also the reason why many people like linux. It is relatively short but powerful. I will list the common Linux commands I have learned for your reference only.
For more linux C/C++ learning materials, you can pay attention to the WeChat public account: "C and C plus" Reply: "Linux" can be obtained
1. System Information Linux Common Commands
arch show the machine's processor architecture
uname -m show the machine's processor architecture
uname -r show the kernel version in use
dmidecode -q show the hardware system components - (SMBIOS / DMI)
hdparm -i /dev/hda list the architecture of a disk Features
hdparm -tT /dev/sda Perform test read operations on disk
cat /proc/cpuinfo Show CPU info info
cat /proc/interrupts Show interrupts
cat /proc/meminfo Verify memory use
cat /proc/swaps Show what swap is used
cat /proc/version show kernel version
cat /proc/net/dev show network adapters and statistics
cat /proc/mounts show mounted filesystems
lspci -tv list PCI devices
lsusb -tv show usb device
date show system Date
cal 2022 Display the calendar in 2022
date 061217002022.00 Set date and time - month day hour minute year. second
clock -w save time modification to BIOS
Second, the system shutdown, restart Linux common basic commands
shutdown -h now shuts down the system
init 0 shuts down the system
telinit 0 shuts down the system
shutdown -h hours:minutes & shuts down the system at the scheduled time
shutdown -c cancels the system shutdown at the scheduled time
shutdown -r now restarts
reboot restarts the
logout logout
3. Basic commands commonly used in Linux for directory operations
1. Directory switching cd
Command: cd directory
cd / switch to the root directory
cd /usr switch to the usr directory under the root directory
cd ../ switch to the upper directory or cd ..
cd ~ switch to the home directory
cd - switch to the last visited directory
2. Directory view ls [-al]
Command: ls [-al]
ls View all directories and files in the
current directory ls -a View all directories and files in the current directory (including hidden files)
ls -l or ll List View all directories and files in the current directory (list view, show more information)
ls /dir View all directories and files in the specified directory such as: ls /usr
3. Directory operations [add, delete, modify, check]
Create a directory [Add] mkdir
Command: mkdir directory
mkdir aaa Create a directory named aaa in the current directory
mkdir /usr/aaa Create a directory named aaa in the specified directory
Delete a directory or file [delete] rm
Command: rm [-rf] directory
Delete files:
rm files delete files in the current directory
rm -f files delete files in the current directory (do not ask)
Delete a directory:
rm -r aaa recursively delete the aaa directory in the current directory
rm -rf aaa recursively delete the aaa directory in the current directory (do not ask)
Delete all:
rm -rf * Delete all directories and files in the current directory
rm -rf /* [Suicide command! Use with caution! Use with caution! Use with caution! 】Delete all files in the root directory
Note: rm can not only delete directories, but also other files or compressed packages. For the convenience of everyone's memory, no matter if any directory or file is deleted, use rm -rf directory/file/compressed package directly
Directory modification [change] mv and cp
Rename directory
command: mv current directory New directory
for example: mv aaa bbb Change directory aaa to bbb
Note: The syntax of mv can not only rename directories but also rename various files, compressed packages, etc.
Cut directory
command: mv directory name new location of the directory
Example: Cut the aaa directory in the /usr/tmp directory to the /usr directory mv /usr/tmp/aaa /usr
Note: The mv syntax can not only cut directories Cut operation, can perform cut operation on files and compressed packages, etc.
Copy directory
command: cp -r directory name directory copy target location -r stands for recursion Example: copy the aaa directory in the /usr/tmp directory to the /usr directory cp
/usr/tmp/aaa /usr
You can copy directories and files, compressed packages, etc., without writing -r recursion when copying files and compressed packages
search directory [check] find
Command: find directory parameter file name
Example: find /usr/tmp -name 'a*' Find all directories or files starting with a in the /usr/tmp directory
Four, file operation Linux common commands
1. File operations [add, delete, modify, check]
Create a new file [Add] touch
command: touch file name
Example: Create a file named aa.txt in the current directory touch aa.txt
Delete file [Delete] rm
command: rm -rf file name
Modify the file [change] vi or vim
[3 modes of vi editor]
Basically vi can be divided into three states, namely command mode (command mode), insert mode (Insert mode) and bottom line mode (last line mode), the functions of each mode are as follows :
1) Command mode command mode)
Control the movement of the screen cursor, delete characters, words or lines, search, move and copy a section and enter Insert mode, or go to last line mode.
Common commands in command line mode:
【1】Control cursor movement: ↑, ↓, j
【2】Delete current line: dd
【3】Search: / character
【4】Enter edit mode: ioa
【5】Enter bottom line mode ::
2) Edit mode (Insert mode)
Only in Insert mode, text input can be done, press "ESC" key to return to command line mode.
Common commands in edit mode:
【1】ESC Exit edit mode to command line mode;
3) In last line mode,
save the file or exit vi, and you can also set the editing environment, such as searching for strings, listing line numbers ……Wait.
Common commands in bottom line mode:
[1] Exit editing: :q
[2] Force quit: :q!
[3] Save and exit: :wq
open a file
Command: vi filename
Example: Open the aa.txt file in the current directory vi aa.txt or vim aa.txt
Note: After using the vi editor to open the file, it cannot be edited, because it is in command mode at this time, click i/a/o on the keyboard to enter the editing mode.
edit file
Use the vi editor to open the file and click the button: i, a or o to enter the editing mode.
i: start inserting before the character where the cursor is
a: start inserting after the character where the cursor is
o: insert a new line below the line where the cursor is
Save or cancel editing
save document:
Step 1: ESC to enter command line mode
Step 2: : Enter bottom line mode
Step 3: wq save and exit editing
Cancel editing:
Step 1: ESC to enter command line mode
Step 2: : Enter bottom line mode
Step 3: q! Cancel this modification and exit editing
File viewing [check]
File viewing command: cat/more/less/tail
cat: see the last screen
Example: Use cat to view the /etc/sudo.conf file, only the content of the last screen can be displayed
cat sudo.conf
more: percentage display
Example: use more to view the /etc/sudo.conf file, the percentage can be displayed, carriage return can go to the next line, space can go to the next page, q can exit to view
more sudo.conf
less: turn pages to view
Example: use less to view /etc/sudo.conf file, use PgUp and PgDn on the keyboard to page up and down, q to end view
less sudo.conf
tail: specify the number of lines or dynamically view
Example: Use tail -10 to view the last 10 lines of /etc/sudo.conf file, Ctrl+C to end
tail -10 sudo.conf
2. Permission modification
rwx: r stands for readable, w stands for writable, x stands for the file is an executable file, if rwx becomes - at any position, it stands for unreadable or writable or non-executable file.
Example: Change the permission of aaa.txt file to executable file permission, the permission of aaa.txt file is -rw-------
The first one: - means it is a file, and d means a folder.
The first paragraph (3 digits): the permission of the owner The second paragraph
(3 digits): the group that the owner belongs to, and the permission of the group members.
(Last 3 digits): Represents the permissions of other users
421 421 421
- rw- --- --
Five, compressed file operation Linux common commands
1. Packing and compression
The extension of the compressed file in Windows .zip/.rar
The packaged file in
linux: aa.tar The compressed file in
linux: bb.gz The packaged and compressed file in linux: .tar.gz
Package files in Linux generally end with .tar, and compressed commands generally end with .gz.
In general, packaging and compression are carried out together, and the suffix name of the packaged and compressed file is generally .tar.gz.
Command: tar -zcvf Pack the compressed file name of the file to be packed
Among them: z: call the gzip compression command to compress
c: pack the file
v: display the running process
f: specify the file name
Example: pack and compress the files under /usr/tmp The compressed package of all files is named xxx.tar
tar -zcvf ab.tar aa.txt bb.txt
or: tar -zcvf ab.tar *
2. Decompression
Command: tar [-zxvf] compressed file
where: x: represents decompression
Example: decompress ab.tar under /usr/tmp to the current directory
Example: Extract the ab.tar under /usr/tmp to the root directory /usr
tar -xvf ab.tar -C /usr------C represents the specified decompression location
Six, find the command Linux common commands
1、grep
grep command is a powerful text search tool
Example of use:
ps -ef | grep sshd Find the specified ssh service process
ps -ef | grep sshd | grep -v grep Find the specified service process, exclude the gerp body
ps -ef | grep sshd -c Find the number of the specified process
2、find
The find command searches a directory structure for files and performs the specified action on the search results.
find searches the current directory and its subdirectories by default, and does not filter any results (that is, returns all files), displaying them all on the screen.
Example of use:
find . -name "*.log" -ls Find files ending in .log in the current directory and display detailed information.
find /root/ -perm 600 Find files with a permission of 600 in the /root/ directory
find . -type f -name "*.log" Find the current directory and find ordinary files ending with .log
. -type d | sort Find the current All directories and sort
find . -size +100M Find files larger than 100M in the current directory
3、locate
locate allows users to quickly search for a path. By default, it is automatically updated once a day, so the latest changed files cannot be found using the locate command. To avoid this situation, you can use the updatedb command to manually update the database before using locate. If there is no queried data in the database, the error locate: can not stat () `/var/lib/mlocate/mlocate.db': No such file or directory will be reported! updatedb can be!
yum -y install mlocate If it is a streamlined CentOS system, you need to install the locate command
Example of use:
updatedb
locate /etc/sh Search all files starting with sh in the etc directory
locate pwd Find all files related to pwd
4、whereis
The whereis command is used to locate executable files, source code files, and help files in the file system. The attributes of these files should belong to source code, binary files, or help files.
Example of use:
whereis ls finds all files related to the ls file
5、which
The function of the which command is to search the location of a system command in the path specified by the PATH variable and return the first search result.
Example of use:
which pwd finds the path where the pwd command is located
which java finds the path of java in path
Seven, su, sudo
1、his
su is used to switch between users. However, the user before the switch remains logged in. If it is root to switch to ordinary or virtual users, no password is required, otherwise, ordinary users need password authentication to switch to any other user.
su test: switch to the test user, but the path is still the /root directory
su - test : switch to the test user, the path becomes /home/test
su : switch to the root user, but the path is still the original path
su - : switch to root user, and the path is /root
su is not enough: If a user needs to use root privileges, the root password must be told to this user.
Exit to return to the previous user: exit
2、sudo
sudo is designed for all ordinary users who want to use root privileges. Allows ordinary users to temporarily use root privileges. Just enter the password for your account.
Enter the sudo configuration file command:
vi /etc/sudoer or visudo
case:
Allow hadoop user to execute various application commands as root, need to enter the password of hadoop user.
hadoop ALL=(ALL) ALL
case:
Only the hadoop user is allowed to execute the ls and cat commands as root without entering a password.
In the configuration file:
hadoop ALL=NOPASSWD: /bin/ls, /bin/cat
8. System Services
service iptables status --View the status of the iptables service
service iptables start --Open the iptables service
service iptables stop --Stop the iptables service
service iptables restart --Restart the iptables service
chkconfig iptables off --Turn off the iptables service's self-starting
chkconfig iptables on - -Enable the iptables service to start automatically at boot
Nine, network management Linux common commands
1. Hostname configuration
[root@node1 ~]# vi /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=node1
2. IP address configuration
[root@node1 ~]# vi /etc/sysconfig/network-scripts/ifcfg-eth0
3. Domain name mapping
The /etc/hosts file is used for IP address resolution when accessing by hostname. So, what kind of host name you want to access, you need to put the host name and its corresponding ip address.
[root@node1 ~]# vi /etc/hosts
#### Add
192.168.52.201 node1
192.168.52.202 node2
192.168.52.203 node3 at the end
Ten, timed task command crontab configuration Linux common commands
crontab is a command used by Unix and Linux to set up scheduled tasks. Through the crontab command, you can execute specified system commands or shell scripts at regular intervals. The unit of time interval can be minutes, hours, days, months, weeks, and any combination of the above.
crontab installation:
yum install crontabs
service operation instructions:
service crond start ## start the service
service crond stop ## shut down the service
service crond restart ## restart the service
1. Command format
crontab [-u user] file
crontab [-u user] [ -e | -l | -r ]
Parameter Description:
-u user: used to set the crontab service of a user
file: file is the name of the command file, indicating that file is used as the task list file of crontab
and load crontab.
-e: Edit the contents of a user's crontab file. If no user is specified, it means editing the current
The user's crontab file.
-l: Display the contents of a user's crontab file. If no user is specified, it means that the current
Contents of the user's crontab file.
-r: delete the scheduled task configuration, delete a user's crontab from the /var/spool/cron directory
file, if no user is specified, the crontab file of the current user is deleted by default.
Command example:
crontab file [-u user] ## Replace the current crontab with the specified file
crontab -l [-u user] ## List the user's current crontab
crontab -e [-u user] ## Edit the user's current crontab
2. Configuration instructions
Command: * * * * * command
Explanation: Time division day month week order
The first column indicates minutes 1 to 59 with * or */1 for every minute
The second column represents the hour from 0 to 23 (0 means 0 o'clock)
The third column represents the date 1 to 31
The fourth column represents the month 1 to 12
The 5th column identifies the day of the week 0 to 6 (0 means Sunday)
Column 6 Command to run
Eleven, other common Linux commands
View the current directory: pwd
Command: pwd View the current directory path
View processes: ps -ef
Command: ps -ef View all running processes
End the process: kill
command: kill pid or kill -9 pid (forcibly kill the process) pid: process number
Network communication command:
ifconfig: View network card information
Command: ifconfig or ifconfig | more
ping: Check the connection to a machine
Command: ping ip
netstat -an: View the current system port
Command: netstat -an
Search for the specified port
Command: netstat -an | grep 8080
Configure the network
Command: setup
Restart the network
Command: service network restart
Switch user
Command: su - username
Turn off the firewall
Command: chkconfig iptables off
or:
iptables -L;
iptables -F;
service iptables stop
modify file permissions
Command: chmod 777
Clear screen
command: ctrl + l
After the shortcut key esc in vi mode :
Save and exit shortcut: shift+z+z
The cursor jumps to the last line shortcut key: shift+g
delete a line: dd
Copy a line of content: y+y
Paste the copied content :p
12. More linux C/C++ learning materials
For more linux C/C++ learning materials, you can pay attention to the WeChat public account: "C and C plus" Reply: "Linux" can be obtained