What output would you expect after typing the following:

Question

$ prog1
$ e2=20; export e2
$ e4=40 prog1

Here are two programs called prog1 and prog2:
$ cat prog1
e1=100
export e1
e2=200
e3=300 prog2
$ cat prog2
echo e1=$e1 e2=$e2 e3=$e3 e4=$e4
$

Answer 1

The output demonstrates how variables live within their own shell unless forced otherwise with the export command, so the result of the invocation is:
$ prog1
e1=100 e2= e3=300 e4=
$ e4=40 prog1
e1=100 e2=200 e3=300 e4=40
$ prog1
e1=100 e2=200 e3=300 e4=
$