[VIM]處理檔案中不特定數量無意義空行 & how to replace ^M with vim

https://stackoverflow.com/questions/16414410/delete-empty-lines-using-sed
不會保留縮排空行，需要只能砍空超過一行的


https://stackoverflow.com/questions/12598916/how-to-use-sed-to-remove-only-double-empty-lines

處理檔案中不特定數量無意義空行

sed 'N;/^\n$/D;P;D;'  main.i > main3.i





how to replace ^M  with vim :

1.顯示^M: e ++ff=unix


2.取代:24,39s/\r$//g


3.改回不顯示: e ++ff=dos











sed  -i   + backup file

sed -i.bak '/pattern to match/d' ./infile