I'm trying to find an easy way to turn logging to a text file on and off much like the example seen here in Python. Their solution was to use a valid file name where logging is desired and to use the null device 'dev/null' otherwise. They're using redirection but I wish to use fopen.
Is there some way to do something like the following, which word work for Unix or Windows systems if that matters.
nullFID = fopen('/dev/nul', 'w')
The script I'm altering could benefit greatly with detailed logging in certain breaking scenarios where we want to pull up a fine level of detail for a handful of files but that would otherwise grow too large for the batch processing the script normally targets.
Looks like this can be done, someone posted an answer on MathWorks using a similar term of "null file". Not sure if that's valid terminology but could be a shortening of "null device file".
The way to reference the null device is OS dependent...
nullFID = fopen( 'NUL:' ); % Windows
nullFID = fopen('/dev/null'); % UNIX
And it also appears the reference varies from Matlab releases. Consider the following script
ver
nullFID = fopen( 'NUL:' , 'w' )
fprintf( nullFID , '12345' )
nullFID = fopen( 'NUL:' )
fprintf( nullFID , '12345' )
nullFID = fopen('NUL' , 'w' )
nullFID = fopen('NUL' )
And the following output generated from two versions of Matlab...
R2011b
>> ver
-------------------------------------------------------------------------------------
MATLAB Version 7.13.0.564 (R2011b)
MATLAB License Number: xxxx
Operating System: Microsoft Windows 7 Version 6.1 (Build 7601: Service Pack 1)
Java VM Version: Java 1.6.0_17-b04 with Sun Microsystems Inc. Java HotSpot(TM) 64-Bit Server VM mixed mode
-------------------------------------------------------------------------------------
MATLAB Version 7.13 (R2011b)
>> nullFID = fopen( 'NUL:' , 'w' )
nullFID = 119
>> fprintf( nullFID , '12345' )
ans = 5
>> nullFID = fopen( 'NUL:' )
nullFID = 120
>> fprintf( nullFID , '12345' )
ans = 0
>> nullFID = fopen('NUL' , 'w' )
Warning: You have chosen a reserved DOS device name for your filename.
Please choose another valid filename
nullFID = -1
>> nullFID = fopen('NUL')
nullFID = -1
R2015a
>> ver
----------------------------------------------------------------------------------------------------
MATLAB Version: 8.5.0.197613 (R2015a)
MATLAB License Number: 1093113
Operating System: Microsoft Windows 7 Professional Version 6.1 (Build 7601: Service Pack 1)
Java Version: Java 1.7.0_60-b19 with Oracle Corporation Java HotSpot(TM) 64-Bit Server VM mixed mode
----------------------------------------------------------------------------------------------------
MATLAB Version 8.5 (R2015a)
>> nullFID = fopen( 'NUL:' , 'w' )
nullFID = -1
>> fprintf( nullFID , '12345' )
Error using fprintf
Invalid file identifier. Use fopen to generate a valid file identifier.
>> nullFID = fopen( 'NUL:' )
nullFID = 8
>> fprintf( nullFID , '12345' )
ans = 0
>> nullFID = fopen('NUL' , 'w' )
Warning: You have chosen a reserved DOS device name for your filename.
Please choose another valid filename.
nullFID = -1
>> nullFID = fopen('NUL' )
nullFID = -1