https://stackoverflow.com/questions/15758814/turning-multiple-lines-into-one-line-with-comma-separated-perl-sed-awk file aaa bbb ccc ddd xargs cat file | xargs result aaa bbb ccc ddd xargs improoved cat file | xargs | sed -e ‘s/ /,/g’ result aaa,bbb,ccc,ddd 변태 같은 명령어라고 표현해야 하나..
