Echo is the basic command for terminal printing. Use:
$ Echo "hello world"
$ Echo hello world
$ Echo 'Hello world'
$ Echo $ PATH
[Name Description]
By default, echo adds a line break symbol at the end of each line. Option-n is used to ignore line breaks at the end of a line;
Exclamation point (!) It is a special symbol. If a string has an exclamation mark, it should not be placed in double quotation marks (""). You can also use escape characters without double quotation marks or single quotation marks:
$ Echo hello world!
$ Echo 'Hello world! '
$ Echo "hello world \!"
When the echo command without quotation marks is used, the semicolon (;) cannot be printed, because the semicolon is used as the command Separator in the bash shell;
When you use the echo command of single quotes (''), baseh does not evaluate the variable ($ var) in single quotes, but only outputs as is;
$ Echo 'hello, $ vName .'
Hello, $ vName. # output this line;