Specs

read(device(), :all | :line | non_neg_integer()) :: chardata() | nodata()

Reads from the IO device.

The device is iterated by the given number of characters or line by line if :line is given. Alternatively, if :all is given, then whole device is returned.

It returns:

• data - the output characters

• :eof - end of file was encountered

• {:error, reason} - other (rare) error condition; for instance, {:error, :estale} if reading from an NFS volume

If :all is given, :eof is never returned, but an empty string in case the device has reached EOF.