linux-the difference between single quotes, double quotes, and anti-quotes.

One, single and double quotation marks

Both single and double quotes are meant to solve the problem of having spaces in the middle.

Because the space in Linux as a very typical delimiter, such as String1=this is astring, so execution will be error. To avoid this problem, single and double quotes are generated. Their difference is that the single

The quotation marks deprive the special meaning of all characters, while the ' $ ' (parameter substitution) and ' ' (command substitution) in double quotation marks are the exception. So, there's basically no difference between the two, unless the parameter substitution $ and the command substitution are encountered in the content

'.

So here's the result:
Num=3
Echo ' $num '
$num
echo "$num"
3
Therefore, if you need to use both of these symbols in the double quotation mark "", you need to escape with a backslash.

Second, anti-quote "'

The usage of this thing, and $ () is the same. When you execute a command, the statements in either, or $ () are executed once as a command, and the result is added to the original command for re-execution.

For example: Echo ' ls ' will first execute LS to get xx.sh and so on, then replace the original command as: Echo xx.sh the last execution result is xx.sh so, usually we encounter the output of a bunch of command execution results in a variable, need to use this

The command substitution is also understandable.

linux-the difference between single quotes, double quotes, and anti-quotes.