Summary of Linux commands commonly used in work

Use more open source tools such as docker and kubernetes at work. The work is basically based on the Linux system. Record the Linux commands that are commonly used in work. It will be more convenient to use each command with certain parameters. Only commonly used commands and parameters are recorded here

1. System work command

1. echo command

The echo command is used to output a string or the value of a variable after extraction in the terminal. The format is echo [string | $variable]

Similar to system.out.println in Java

[root@k8s-master ~]# echo "hello world"
hello world
[root@k8s-master ~]# str="hello world"
[root@k8s-master ~]# echo $str
hello world

2. date Command

Used to display and set the system time, the format is data [option] [+specified format]

Common parameters of data

1. %t Tab [tab key]
2. %H Hours (0~23)
3. %I Hours (0~12)
4. %M Minutes (0~59)
5. %S seconds (0~59)
6. %J Day of the year

[root@k8s-master ~]# date
Thu Apr 11 13:42:20 CST 2019
[root@k8s-master ~]# date "+%Y-%m-%d %H:%M:%S"
2019-04-11 13:43:41
[root@k8s-master ~]# date "+%j"
101

3. reboot command

The reboot command is used to reboot the system. Its format is reboot.

[root@k8s-master ~]# reboot

4. poweroff command

The poweroff command is used to shut down the system. Its format is poweroff

[root@k8s-master ~]# poweroff

5. wget Command

The wget command downloads network files on the terminal. The format is wget [parameter] [download address]
Parameter Introduction

1. -b background download mode
2. -P Download to the specified directory
3. -t maximum number of attempts
4. -c Resume downloading
5. -p download all resources in the page
6. -r recursive download

[root@k8s-master ~]# wget http://www.linuxprobe.com/docs/LinuxProbe.pdf

6. ps Command

The ps command is used to view the process status in the system. The format is [ps parameter]
Parameter Introduction

1. -a Display all processes
2. -u Display user and other detailed information
3. -x displays processes that have no controlling terminal

[root@k8s-master ~]# ps aux

7. top Command

The top command is used to dynamically monitor detailed information such as process status and system load. The top command is very powerful, equivalent to the "enhanced Windows Task Manager" in Linux.

top - 10:41:34 up 12 days, 19:14, 2 users, load average: 1.00, 1.06, 0.92
Tasks: 635 total, 2 running, 633 sleeping, 0 stopped, 0 zombie
%Cpu(s): 4.6 us, 1.2 sy, 0.0 ni, 92.1 id, 1.7 wa, 0.0 hi, 0.1 si, 0.3 st
KiB Mem : 16268340 total, 7407372 free, 4552160 used, 4308808 buff/cache
KiB Swap: 0 total, 0 free, 0 used. 10456728 avail Mem 

 PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND                                                        
32056 root 20 0 868460 790968 42808 S 25.2 4.9 1915:18 kube-apiserver 

The first five lines of the top command are overall system statistics. They represent system load, process status, CPU, physical memory, and virtual memory usage respectively.

8. pidof Command

The pidof command is used to query the pid value of a service. The format is: [pidof parameter service name]

 [root@k8s-master ~]# pidof java
  27775

9. kill and killall commands

The kill command is used to terminate the process format of pid value [kill parameter pid value], and the killall command is used to terminate all processes of a specific service [killall parameter a process name].

2. State monitoring command

The system status monitoring command can provide a faster and better understanding of the Linux server. Including the use of commands related to the system's network card network, system kernel, system load, memory usage, and the number of currently started terminals.

1. ifconfig command

ifconfig is used to obtain information such as network card configuration and network operation status. The format is [ifconfig network device parameters]
Simply enter ifconfig to view all network card information.

[root@k8s-master ~]# ifconfig
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
    inet 192.168.223.16 netmask 255.255.255.0 broadcast 192.168.223.255
    inet6 fe80::20c:29ff:fede:d1af prefixlen 64 scopeid 0x20<link>
    ether 00:0c:29:de:d1:af txqueuelen 1000 (Ethernet)
    RX packets 66 bytes 8951 (8.7 KiB)
    RX errors 0 dropped 0 overruns 0 frame 0
    TX packets 88 bytes 10153 (9.9 KiB)
    TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

When checking the network card information, you mainly check the network card name, IP address after inet, physical address after ether, number of received and sent data packets of RX and TX, and cumulative traffic.

When checking the network card information, you mainly check the network card name, IP address after inet, physical address after ether, number of received and sent data packets of RX and TX, and cumulative traffic.

2. uname Command

Use the uname command to view information such as the system kernel and system version. Generally, it is used with the -a parameter to view complete relevant information.

[root@k8s-master ~]# uname -a
Linux mysql 3.10.0-693.el7.x86_64 #1 SMP Tue Aug 22 21:09:27 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

Also view details of the current system version.

[root@k8s-master ~]# cat /etc/redhat-release 
CentOS Linux release 7.4.1708 (Core)

3. uptime command

The uptime command can be used to view system load information. Including system time, system running time, current terminal users, and system pressure status in the last 1 minute, 5 minutes, and 15 minutes. The lower the load value, the better. Do not exceed 1 for a long time, and do not exceed 5 in a production environment.

[root@k8s-master ~]# uptime
 11:15:53 ​​up 14 min, 2 users, load average: 0.00, 0.04, 0.05

4. free command

Displays the current system memory usage information. The format is [free -h]

[root@k8s-master ~]# free -h
       total used free shared buff/cache available
Mem: 15G 4.4G 6.7G 739M 4.4G 9.8G
Swap: 0B 0B 0B

5. histroy Command

The histroy command is used to display the commands executed in history. The format is [history -c]
Executing the history command can display the most recent 1000 command records executed by the current user on the local computer. You can also use the "! code number" method to repeat a command.

[root@k8s-master ~]# history
  1 ls
  2 cd /
  3 ls
  4 hostname
  5 ls
  6 cd mysql/
  7 ls
  8 cd data/

3. Working directory switching command

The Linux used during work is almost never graphically installed. To reduce expenses. We basically use command terminal mode. During use, it is naturally not possible to switch the working directory as easily as in the Windows system. The working directory is the user's current location.

1. pwd Command

The pwd command displays the absolute path format of the current working directory [pwd option]

[root@k8s-master ~]# pwd
/root

2. cd Command

The cd command switches the working path. This should be the most commonly used command in Linux.

[root@k8s-master ~]# cd /home/
[root@k8s-master home]#

3. ls Command

The ls command displays file information. Format [ls options]
The -l parameter can view file attributes.

[root@kubemaster home]# ls
config docker software test.yaml
[root@kubemaster home]# ls -l
total 12
drwxr-xr-x 4 root root 35 Feb 13 09:46 config
drwx--x--x 11 root root 130 Mar 11 16:37 docker
drwxr-xr-x 4 root root 30 Jan 10 14:08 software
-rw-r--r-- 1 root root 234 Sep 6 2018 test.yaml

4. File directory management commands

1. mkdir Command

The mkdir command is used to create a blank directory. The format is [mkdir option directory]
You can use the -p parameter to recursively create directories.

[root@kubernetes ~]# mkdir -p /a/b/c
[root@kubernetes ~]# cd /a/b/c
[root@kubernetes c]# pwd
/a/b/c

2. cp command

The cp command is used to copy files or directories. The format is cp [options] source file target file

[root@kubernetes ~]# cp install.log x.log
[root@kubernetes ~]# ls
install.log x.log

3. mv Command

The mv command is used to cut files or rename files. The format is mv [options] source file [target path | target file name]

[root@kubernetes ~]# mv x.log linux.log
[root@kubernetes ~]# ls
install.log linux.log

4. rm Command

The rm command is used to delete files or directories. The format is rm [options] file. When deleting files in a Linux system, the system will ask you by default whether you want to perform the deletion operation. If you don’t want to always see this repetitive confirmation message, you can follow the rm command with the -f parameter to force deletion.

[root@kubernetes ~]# rm install.log
rm: remove regular empty file 'install.log'? y
[root@kubernetes ~]# rm -f linux.log
[root@kubernetes ~]# ls
[root@kubernetes ~]#

The above is a summary of the commonly used Linux commands introduced by the editor. I hope it will be helpful to everyone. If you have any questions, please leave me a message and the editor will reply to you in time. I would also like to thank everyone for their support of the 123WORDPRESS.COM website!