sorting - Linux sort utility, possible to sort on minimum value of multiple columns? -

a text file has multiple columns of 1 "start" , other "end", both holding positive integer values. however, since objects described (think of them vectors placed on number line) have direction these can end in either orientation this:

 400  20  (start @ 400, end @ 20)   10 100  (start @ 10, end @ 100 )  300  15  (start @ 300, end @ 15) 

often 1 order these ranges, opposed start or end value. range limits row are:(min(start,end), max(start,end)). sorting lower limit give order:

  10 100  (start @ 10, end @ 100 )  300  15  (start @ 300, end @ 15)  400  20  (start @ 400, end @ 20) 

this type of sort can accomplished using perl or other similar scripting language, first generating lower range limit, , sorting on it. however, far can tell there no way directly using usual unix/linux sort utility. specifying this:

sort -k 1,1n -k 2,2n 

sorts on first, if there tie, sorts on second. isn't desired sort though.

is there way type of "minimum of multiple column" sort using "sort"?