Script output is provided by the echo and printf commands, which we described in Screen Output:

$ echo "Hello world"
Hello world
$ printf "I am %d years old
" `expr 20 + 20`
I am 40 years old

Input is provided by the read command, which reads one line from standard input and stores it in a variable:

$ read name
Sandy Smith <ENTER>
$ echo "I read the name $name"
I read the name Sandy Smith