Common parentheses in Shell Usage Summary Linux Course learning

LinuxSmall Brackets()and curly braces{}is the execution of one of these commands, but there is a certain difference, and its specific meaning is as follows:

(): Commands within parentheses are executed in a child shell

(()): Compare and calculate the values in parentheses

$ (): command substitution, equivalent to anti-quote '

$ (()): integer Arithmetic

{}: Manipulating a set of characters within parentheses

${}: reference to Variable

[]: Condition test

[[]]: Conditional test to support regular expressions

$[]: integer operation

these are the Linux The various parentheses in the specific interpretation, for often confused people, can be compared to study, I believe, more than a few times also are divided clearly!

Common parentheses in Shell Usage Summary Linux Course learning