[Linux] application of reverse quotation marks (') in shell

[Linux] application of reverse quotation marks (') in shell
The quotation mark (') is located at the top of the Tab key of the keyboard and the left side of the key 1. Note the difference between it and the single quotation mark (') on the left side of the Enter key.

The reverse quotation mark (') is used to replace commands in Linux. Command replacement means that shell can insert the standard output of a command to any location in a command line.

For example:

Cl @ cl-OptiPlex-380 :~ $ Date October 29, 2014 15:14:46 CSTcl @ cl-OptiPlex-380 :~ $ Echo 'date' | cut-d'-f1-4 Wednesday, October 29, 2014

We can see that the date command in the back quotes ''is executed first, and then the date command output is replaced with the corresponding position.

Very valid metacharacters are often used in shell.