Linux 命令和单引号

Question

I thought the single quotes simply reserve the literal value of each character within the quotes and do not interfere with the command result except for those character-escaping situations.

For example, the two commands below returned the same result.

$ ls /home/testuser/tmp1
$ ls '/home/testuser/tmp1'

This command below ran successfully.

$ cp /home/testuser/tmp1/* /home/testuser/tmp2

However, the command below ran into error.

$ cp '/home/testuser/tmp1/*' /home/testuser/tmp2 
cp: cannot stat '/home/testuser/tmp1/*': No such file or directory

What did I do wrong here?

Answer 1

* is what you call a character escaping situation. Since you preserved the literal value of * , it lost its meaning of "all files", and cp instead tries to copy a file named literally * .

When you run:

cp /home/testuser/tmp1/* /home/testuser/tmp2 

The shell will transparently rewrite it into:

cp /home/testuser/tmp1/bar /home/testuser/tmp1/foo /home/testuser/tmp2 

This process is known as "pathname expansion" or "globbing". When you quote the * , this rewrite does not happen.