How to set commands output as a variable in a batch file

Question

Is it possible to set a statement\'s output of a batch file to a variable, for example:

findstr testing > %VARIABLE%

echo %VARIABLE%

Answer 1

To read a file...

set /P Variable=

To Write a file

@echo %DataToWrite%>File.txt

note; having spaces before the <> character causes a space to be added at the end of the variable, also

To add to a file,like a logger program, First make a file with a single enter key in it called e.txt

set /P Data=log0.txt

your log will look like this

Entry1
Entry2 

and so on

Anyways a couple useful things