Linux Learning 5

The shell I'm using for Ubuntu comes with bash.

quotation marks in 1.bash

': (single quote) What is the output of a strong reference?

"; (double quotes) Weak references are variable substitution

·; (Anti-quote) command replacement

2.echo

-N No Line break

-E will escape the output after \ t \ n

echo "Hello\tworld" output Hello\tworld echo-e "Hello\tworld" Hello World

3.shell can have a child shell, in a new process, and open a new shell

The variable is valid only for the current shell and is not valid for the child shell.

4. Declaring a variable

Declare-i declared as Cosmetic

Declare-a declaring an array

5. Referencing variable values

${age}

Undo Variable

Unset age

Read-only variables

ReadOnly age=23