how does below tr command replace nonletters with newlines?
I think I understand tr -cs '\n' part.. but what is
A-Za-z\' <--- what is this??
tr -cs A-Za-z\' '\n' |
-c --complement
-s, --squeeze-repeats
replace each input sequence of a repeated character that is listed in SET1 with a single occurrence of that charac-
ter