Question

I’m writing a C program under Android/Linux that runs a system command. The command outputs some text to stdout, and I’m trying to capture the output into a string or character array.

For example:

system("ls");

would list the contents of the current directory to stdout, and I would like to be able to capture that data into a variable programmatically in C.

How do I do this?

Thanks.

Answer 1

You want to use popen. It returns a stream, like fopen. However, you need to close the stream with pclose. This is because pclose takes care of cleaning up the resources associated with launching the child process.

FILE *ls = popen("ls", "r");
char buf[256];
while (fgets(buf, sizeof(buf), ls) != 0) {
    /*...*/
}
pclose(ls);