13.5.11 EXIST Specifier

The EXIST specifier asks whether a file exists and can be opened. It takes the following form:

EXIST = ex

ex
Is a scalar default logical variable that is assigned one of the following values:

.TRUE.	If the specified file exists and can be opened, or if the specified unit exists
.FALSE.	If the specified file or unit does not exist or if the file exists but cannot be opened

The unit exists if it is a number in the range allowed by the processor.