WHY

sed -r ":a; N; /\n(<div)/!ba; s//\1/" a.txt > b.txt
复制代码

gawk "BEGIN{RS=\"\n^<div\"}{if(flag)printf s\"^<div\";else flag=1;s=$0}END{printf s}" a.txt > b.txt
复制代码

WHY

@echo off
setlocal enabledelayedexpansion
for /f "delims=" %%i in ('findstr /n .* a.txt') do (
    set "curLine=%%i"
    set "curLine=!curLine:*:=!"
    if defined flag (
        if "!curLine:~0,4!" NEQ "<div" (
            echo;!preLine!
        ) else (
            set /p "=!preLine!" <nul
        )
    ) else (
        set flag=1
    )
    set "preLine=!curLine!"
)
if defined flag echo;!preLine!
pause
复制代码