Performs conditional processing in batch programs. IF [NOT] ERRORLEVEL number command IF [NOT] string1==string2 command IF [NOT] EXIST filename command NOT Specifies that Windows should carry out the command only if the condition is false. ERRORLEVEL number Specifies a true condition if the last program run returned an exit code equal to or greater than the number specified. command Specifies the command to carry out if the condition is met. string1==string2 Specifies a true condition if the specified text strings match. EXIST filename Specifies a true condition if the specified filename exists.