CODEWITHSUNDEEP
c++linuxforkstdout
Alon_T
Alon_T

Reputation: 1440

redirect a process started with execv to /dev/null

I have a program that forks(), and the child process is replaced by another process, say A, that is ran through invoking execv(A).

How do I redirect process A's output to /dev/null??

I've so far tried : (The handle error parts are taken care of, and no error occurs)

    pid = fork();
    //check for errors
    if (pid<0){
                  //handle error
    }
    //the child process runs here
    if (pid==0){
        fd = open("/dev/null", O_WRONLY);
        if(fd < 0){
                        //hadnle error
        }
        if ( dup2( fd, 1 )  != 1 ) {
                         //handle error 
        }
        if (execv(lgulppath.c_str(),args)<0){
            //handle error
        }
    }

However, that, understandably doesn't work , since it redirects the child process's output to /dev/null and not process A's, later to replace the child, output.

Any ideas? (I don't have the code of A's process)

Thanks

Upvotes: 1

Views: 3156

Answers (1)

Olaf Dietsche
Olaf Dietsche

Reputation: 74058

One possibility could be, that process A writes to stderr instead of stdout.

Then you must dup2(fd, 2) instead.

If process A writes to stdout and stderr, you must dup2() both:

if (dup2(fd, 1) < 0) {
    // error handling
}

if (dup2(fd, 2) < 0) {
    // error handling
}

Upvotes: 1

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