sort problems

[A/Prof. David F. Davey]

    Okay you sort experts why do these two sorts not work ?
    
    sort << !
     Abe
    Aba
    !
You must say skip leading blanks on the first column (+0 to right)
sort +0b <<
 Abe
Aba
!

    
    sort << !
    Abe
    $Aba
    !
The shell variable $Aba is most likely undefined. "set -x" before the sort
of the here document would show a blank line input in this case. You can
also see what is happening with:

Aba="Aba from shell variable"
sort << !
Abe
$Aba
!