linux - 关于鸟哥书中shell变量测试与替换那张表怎么记忆?

Question

我看到这张图毫无头绪啊,有什么基本的规律能用文字表达出来吗?这张图到底有多大用啊?我能不能当作没看见?

Answer 1

I found out that Brother Bird didn’t draw this picture well. I changed it and it seemed to be coherent

Answer 2

There is really no pattern in this table.
If it were me, I would put it in Evernote and check it anytime when needed.
The more you use it, the easier it will be to remember it.

PS: If it is not to cope with the exam, there is no need to memorize it by rote.

Answer 3

You won’t need it if you don’t write a shell script

Answer 4

You don’t have to memorize the words you often use. Memorizing the words you don’t need will be in vain
See, I only know now that ${i:i:j} takes a substring