Table of contents
Commands used dozens of times a day
Commands used about ten times a day
I was interviewing recently. The plan was to interview several junior operation and maintenance engineers. I interviewed many of them, but I haven’t met a suitable one yet. Maybe it’s because I didn’t have the experience of interviewing others before, so I didn’t master the standard of asking.
Seeing that the resumes are very tall, it is difficult to ask. I saw k8 and containers, but when I asked, either I did it myself, or I didn’t answer clearly. .
As a result, I finally asked, what command should I use to view the last 10 lines of the log, but I hesitated for a long time, only to find that the clown is myself. What I want to say here is that although many of them are cloud resources now, many times Some basic content has been completed for me, but some of the most basic things still need to be clear.
The words in this article are based entirely on my own experience and conclusions. They may be used less now, but in the past, they were basically used every day.
Commands used dozens of times a day
1.cd
Dozens of times a day is actually a small number, especially for companies whose daily operations and maintenance are not so automated.
The function is to switch directories
cd .. switch to the previous directory
cd ~ switch to the root directory
cd - Switch to the directory you were in last time. This command can sometimes be helpful.
2.cp
Copy, -r, -a. These two attributes are used more often.
-r is recursive copy, which can be used to copy directories
If -a is used, the corresponding attributes will be copied, such as some executable files.
3.ls
View the files in the corresponding directory
The most commonly used options are -l and -a
-l can display some creation time, file size, etc. of specific files
-a can display hidden files, such as .ssh, etc.
4.rm
Many developers will joke with us, what about rm -rf
But for operation and maintenance, this command is really used many times a day, and it has not been deleted by mistake in so many years.
Of course, newcomers should be more cautious when using it, and use -f sparingly.
If -r is used, it will be deleted recursively.
5.mv
You can change the location of the file or change the file name.
6.cat
View file contents
Use caution when reading large log files
Commands used about ten times a day
7.ps
View progress
The most commonly used one is -ef
Or -aux
8.top
To put it simply, check the load
You can see the overall load of the server and the load of a single process.
Press a to see the load of all cpu cores
Press m to view the processes taking up the most memory.
9.free
View memory
Can -h, -m
10.tail
The last 10 lines of the file
-n can specify the number of lines
-f can refresh in real time
11.head
View the first 10 lines of the file
You can add -n to view the fixed number of lines
12.ip ad
In fact, the complete version is ip add show
IP ad can be displayed directly
The most used one is to check IP
You can also use ipconfig under Linux
You can use ifconfig under cmd
13. netstat
There is also a similar command nc. Sometimes you can also use lsof.
Used to view ports
netstat -an |grep port
You can view the port based on the process number
netstat -antlp|grep pid
Other commonly used commands
14.touch
Create a file
15.history
View command history
In fact, in operation and maintenance work, it is very useful to view historical commands.
Especially some historical systems that have not been touched for a long time.
You have to look at the history commands to find some records.
16.find
This command is actually very powerful
The most commonly used one is to find files
You can search by name, you can search by time, you can also search by file type.
find / -name test*
find / -mtime 10
find / -type f
17.awk
Commonly used is -F
Split based on specified fields
For example: echo "1-2-3"|awk -F'-''{print $2}'
18.sed
The most commonly used one is the replacement field.
sed -i can directly take effect on the file. Without -i, you can output and view the replacement effect.
sed -i 's/original field/replacement field/g' file name
19.telnet
Detect whether the peer port is open
Can determine whether the peer service is normal
Of course, there might be a wall
20.pwd
Current location path
For example, copying files, etc., sometimes used