Question

I would like to redericting stdout, stderr to file and stdin from char*. My goal is make it in C.

When i run this code:

int main(){
        stdout=fopen("/home/user/file.txt","w");
    printf("aaaa");
    printf("\nbbbb");
    system("/bin/bash");
    sprintf("stdin","exit");
    return 0;
}

File didn’t have for some string and bash take argument from console. Where is bug??

Answer 1

You don’t want to assign to stdout. Instead, you (probably) want to use freopen, in your case like: freopen("/home/user/file.txt","w", stdout);

If/when you’re doing all the processing internally, you’re generally better off writing the code to receive a FILE * as a parameter, and passing the correct value. That doesn’t work when you have external code that writes directly to stdout though.

Edit: I should probably also mention one other serious problem with freopen — no method is provided to restore it to the previous stream. It’s up t you to use freopen again, and know the path that will write to the console (or whatever).