#!/bin/bash

echo "Hello World!" # print a string
echo "Welcome $USER" # print a variable value
echo '$USER' # single quote does not interpret the variable
echo "Today is $(date)" # print the output of a command
echo -e "Number of user login: \c"; who | wc -l # \c keeps the cursor on the same line after the end of the echo, need -e to enable it
echo -e "Hello\n World!" # \n, newline
echo -e The gif files are *.sh # wildcard
exit 0 # 0 represent the program is implemented successfully
			

#!/bin/bash

printf "Hello %s\n" $USER
printf "Hello |%10s|\n" $USER
printf "Hello |%-10s|\n" $USER
printf "Value of PI is: %10.2f\n" 3.1415926
			

• echo escape sequences
• printf command