@echo off
(for /f "delims=" %%a in (a.txt) do (
    set /a m+=1,"test=1/(m%%12*!!(m-1))"||echo;%%a
))>b.txt 2>nul
pause
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@echo off
(for /f "delims=" %%a in (a.txt) do 2>nul set/an+=1,"1/(n%%12*(n-1))"||echo;%%a)>b.txt
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@echo off&set n=-1
:a
if not %n%==-1 set "m=skip=%n% "
(for /f "%m%delims=" %%a in (a.txt) do (
	echo;%%a
	set/an+=12
	goto:a
))>b.txt
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@echo off
echo 批处理数据。记事本b.txt，要a.txt的1行12行24行36行……(12的倍数行)直至a.txt最后一行。
echo by breakme QQ:49849628
set b=
setlocal EnableDelayedExpansion 
rem 读取文件有多少行？并将第一行数据读取
for /f "tokens=1* delims=*" %%i in (a.txt) do set /a b+=1 && if "!b!"=="1" echo %%i>>b.txt

rem 按规律匹配数据 0 开始，每加 12 就读取一行
for /l %%i in (0,12,!b!) DO call :a %%i

exit

:a
set a=
for /f "tokens=1* delims=*" %%i in ('type a.txt') do (
set /a a+=1
if "!a!"=="%1" echo %%i>>b.txt
)
goto :eof
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gawk "!(NR%2)" a.txt | more >b.txt
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