Batch: Checking for null value and writing a string in its place -

i have group of text files contain either 1 line of data or blank. need of files dumped single file. part's easy enough, need blank file return "nodata" or similar string in new file.

setlocal enabledelayedexpansion type nul >c:\somedirectory\dataall.txt   rem find files in direcotry; files %%g in (c:\somedirectory\txt??.txt) ( rem find of text within found files /f "tokens=*" %%t in ('type "c:\somedirectory\%%~ng.txt"') ( set datain=%%t     rem check see if file empty , write nodata final variable if     if "c:\somedirectory\%%~ng.txt" lss 1('set "/a datain=nodata"')     rem check see if file not empty , write data final variable      if "c:\somedirectory\%%~ng.txt" neq 0 ('set /a "datain=%%t"')     rem write datain final text file     >> "c:\somedirectory\dataall.txt" echo !datain! )    )  endlocal 

this duplicates previous text file's data blank one. example, if txt1 has xxx,xxx,xx; txt2 blank; , txt3 x,x,x datall file read:

xxx,xxx,xx

xxx,xxx,xx

x,x,x

how set datain string?

for %%g in (c:\somedirectory\txt??.txt) (  set "datain=no data"  rem find of text within found files  /f "usebackqtokens=*" %%t in ("c:\somedirectory\%%~ng.txt") (   set datain=%%t  )  rem write datain final text file >> "c:\somedirectory\dataall.txt" echo !datain! ) 

relying on "either it's blank or has 1 line" info, set output string datain "not found" value , overwrite 1 data line if it's found. empty file not execute do part of for %%t loop.