So I want to adjust the length of string1. I do this  by inserting a 
spacer in string1 who's length is calculated from the length of string2:

     local diff spacer
     (( diff = $#string2 - 76 ))
     for (( dd=1; dd<diff; dd++ )); do spacer+=' '; done
     ... # spacer will be incorporated into string1, not shown.

It works fine, but I'll bet there's a less laborious way -- some way of 
creating 'spacer' with  'diff' number of spaces without the for loop.  I 
could make 'spacer' too long and then cut it at an index [diff], but I 
doubt that's as simple as it could be.  I know it's there, I just can't 
quite remember.