sed 개행 문자 제거 (정규식)

-  http://stackoverflow.com/questions/1251999/sed-how-can-i-replace-a-newline-n

sed ':a;N;$!ba;s/\n/ /g' file

1. :a create a label 'a'
2. N append the next line to the pattern space
3. $! if not the last line, ba branch (go to) label 'a'
4. s substitute, /\n/ regex for new line, / / by a space, /g global match (as many times as it can)

sed will loop through step 1 to 3 until it reach the last line, getting all lines fit in the pattern space where sed will substitute all \n characters