问题
I have a long-running Matlab script for data processing. I want to send it a flag over stdin to tell it I have new data to process. I also want to read a flag from stdout when it is done processing.
In other words, I have a Process A that sends a flag about once a minute to Matlab. I want Matlab to wait until it receives this flag.
Writing to stdout in a matlab process is as easy as calling fprintf. But how can I read from stdin? Documentation on fopen doesn't mention an input pipe, and neither does fread. How can get a Matlab script to read from stdin?
回答1:
It actually turns out that the solution is as simple as input. Write the following into myscript.m:
str = input('', 's');
fprintf(str);
exit;
Then, run the following in a shell:
echo Hello world | matlab -nosplash -nodisplay -nodesktop -r "myscript"
Indeed, we see that "Hello world" is printed to the console, along with Matlab's startup text.
So, in summary, input reads from stdin, and fprintf writes to stdout.
回答2:
One way to do this is using a named pipe. In a shell, run mkfifo MY_PIPE to make a named pipe. This will make a file-like object called MY_PIPE that you can read and write to. Then, redirect the output of the program sending data to MY_PIPE, e.g. ./program.sh > MY_PIPE. Finally, to read from the pipe in Matlab, you can use fopen('MY_PIPE', 'r').
Note that answer is limited in a few ways:
It will only run in a Linux environment and with access to the shell.
It doesn't make use of Matlab built-ins and is kind of hackish.
来源：https://stackoverflow.com/questions/23875734/how-to-read-from-stdin-in-matlab