Most of the students' feedback on the Shell script is not easy to learn. I feel that after learning the part of the Shell script, I still can't write the script. Let me help you analyze the reasons and explain how to do it to learn the shell script.
The reason why you feel difficult to learn, can't write anything. Because it is too rusty. Writing a shell script actually learns to walk with a baby, learning to ride a bicycle or learning to swim, this is a skilled job.
To write a beautiful script, I summarize the following:
1 Play basic skills
A shell script is essentially a text document composed of multiple Linux system commands plus logic (conditions, loops). To implement a requirement, as long as you can implement it with system commands, the shell script can be implemented. If you don't have Linux commands, how can you write a script?
2 Learn the rules
If you write a few more shell scripts, you will find that many requirements are to intercept small strings from a large string. This requires you to be very proficient in regular expressions, and several tools for working with regular rules should be used proficiently (grep/sed/awk).
3 logical thinking ability
In large shell scripts, there is strong logic, what to do when conditions are met, and what to do when not satisfied. Conditions can also be nested within a condition, or nested loops (for, while, etc.).
This kind of logical ability is not something we have born. It is the skill that needs constant practice and long-term accumulation.
You may ask, where are there so many scripting requirements? The key is that there is no opportunity to practice. Yes, this is indeed a problem, especially for the students who are in the learning stage. What are the needs of the students? If it is okay to go to work, there is a lot of work to do every day, and there are many requirements in the production environment to be implemented with Shell scripts.
For the students in the learning stage, I have considered your situation, so I spent a few months last year, insisting on issuing a Shell practice question every day in the public number, you can use these resources. In fact, many students have only felt a significant improvement after only one month of persistence. 
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