Tests for multi-line regexps with ":s". vim: set ft=vim :

STARTTEST
:" test if replacing a line break works with a back reference
:/^1/,/^2/s/\n\(.\)/ \1/
:" test if inserting a line break works with a back reference
:/^3/,/^4/s/\(.\)$/\r\1/
:" test if replacing a line break with another line break works
:/^5/,/^6/s/\(\_d\{3}\)/x\1x/
:/^1/,$w! test.out
:qa!
ENDTEST

1 aa
bb
cc
2 dd
ee
3 ef
gh
4 ij
5 a8
8b c9
9d
6 e7
77f
xxxxx