[megaloman]

epoddubniy,

Цикл с ожиданием

Код:

@Echo Off
cls
	Set "FileIn=Z:\Box_In\1.txt"
	Set "KeyWord=Ended"
	Set /A Wait=3
	
	Set "stroka="
	:Begin
		>nul FindStr /I /C:"%KeyWord%" "%FileIn%" && (Set "stroka=%KeyWord%" &GoTo :End)
		TimeOut /T %Wait%
		GoTo :Begin
	:End
	Echo "%stroka%"
pause
Exit /B

Код:

@Echo Off
cls
	Set "FileIn=Z:\Box_In\1.txt"
	Set "KeyWord=Ended"
	Set /A Wait=3
	
	Set "stroka="
	:Begin
		FOR /F "usebackq delims= " %%s IN ("%FileIn%") DO If "%%s"=="%KeyWord%" (Set "stroka=%KeyWord%" &GoTo :End)
		TimeOut /T %Wait%
		GoTo :Begin
	:End
	Echo "%stroka%"
pause
Exit /B

При такой постановке Вам вообще не нужна переменная stroka

Код:

@Echo Off
cls
	Set "FileIn=Z:\Box_In\1.txt"
	Set "KeyWord=Ended"
	Set /A Wait=3
	
	:Begin
		>nul FindStr /I /C:"%KeyWord%" "%FileIn%" && GoTo :End
		TimeOut /T %Wait%
		GoTo :Begin
	:End
	Echo "%KeyWord%"
pause
Exit /B

Код:

@Echo Off
cls
	Set "FileIn=Z:\Box_In\1.txt"
	Set "KeyWord=Ended"
	Set /A Wait=3
	
	:Begin
		FOR /F "usebackq delims= " %%s IN ("%FileIn%") DO If "%%s"=="%KeyWord%" GoTo :End
		TimeOut /T %Wait%
		GoTo :Begin
	:End
	Echo "%KeyWord%"
pause
Exit /B