Is there a better way to capture the output of an external program?
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In a Matlab script, I use a command-line program called wgrib2 to extract information from a compressed jpeg2000 file. Presently the information is extracted to a multi-line text file which I later read into Matlab. I save/read the file many times and I suspect that's why my script runs slowly. To avoid disk i/o, I'd like to capture the wgrib2 output to a Matlab variable; apparently this is not directly possible, but with mkfifo it might be possible. Here is how I am doing it, but if there is a better way, please let me know.
!mkfifo myfifo % Make a named pipe
% Call the external program and dump its output to the named pipe
system('wgrib2.exe multi_1.glo_30m.hs.201212.grb2 -ij 1 165 -ij 1 166 -ij 1 254 -ij 1 255 > myfifo &');
fid = fopen('myfifo','r'); % Send output to the named pipe as if it were a file
a = fscanf(fid, '%c'); % Read the output as character
fclose(fid); % Close the fake file
system('rm myfifo'); % Close the named pipe
strToSplitOn = ':val='; % Output values are separated by this sequence
% Split the output and convert to a number
variableWithFileOutput = str2double(regexp(a, strToSplitOn, 'split'));
FYI it is possible to "reuse" the named pipe so in my program where I call wgrib2 thousands of times, I put system('rm myfifo') at the end.