This came out of one of my comments to this question regarding the use of bc in shell scripting. bc puts line breaks in large numbers, e.g.:

> num=$(echo 6^6^3 | bc)
> echo $num
12041208676482351082020900568572834033367326934574532243581212211450\ 20555710636789704085475234591191603986789604949502079328192358826561\ 895781636115334656050057189523456

But notice they aren't really line breaks in the variable. In fooling around with more pipe in the assignment, e.g.:

num=$(echo 6^6^3 | bc | perl -pne 's/\\\n//g')

I realized that while there really is an \n in the bc output, checking echo $num > tmp.txt with hexdump shows the \n (ASCII 10) has definitely become a space (ASCII 32) in the variable assignment.

Why is that?