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High|ander

Member

From: Skövde, Sweden

Registered: 2005-10-28

Posts: 188

Website

C and fork()

Hi

I'm trying to create a simple C program that creates a new process and executes mpg123 in it.
The problem is that the mp3-file is never played.

The code:

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

int main (int argc, char **argv)
{
    int status;
    pid_t pid = fork();

    if (pid < 0 ){
        printf("Fork failed\n");
    }
    else if (pid == 0) {
        execl("mpg123", "file.mp3");
        printf("Lets play\n");
    }
    else {
        printf("Trying to play something\n");
        /* This is the parent process.  Wait for the child to complete.  */
             if (waitpid (pid, &status, 0) != pid) {
             status = -1;
         }
    }
    return 0;
}

Can you see any errors that I have made?

Thanks !

---

When death smiles at you, all you can do is smile back!
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Cerebral

Forum Fellow

From: Waterloo, ON, CA

Registered: 2005-04-08

Posts: 3,108

Website

Re: C and fork()

Do you see "Lets play" appear on the console when you run this?

RETURN VALUE
       If any of the exec() functions returns, an error  will  have  occurred.
       The  return  value  is -1, and the global variable errno will be set to
       indicate the error.

Check the return value of your execl call as well.

Last edited by Cerebral (2008-03-17 20:10:25)

Shaika-Dzari

Member

From: Québec, Canada

Registered: 2006-04-14

Posts: 436

Website

Re: C and fork()

Hello!

Try to write the full path to mpg123.
arg0 must be the program name and other argument (file.mp3 for you).

execl("/usr/bin/mpg123","mpg123", "file.mp3");

@+

Last edited by Shaika-Dzari (2008-03-17 20:18:00)

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Shaika-Dzari
http://www.4nakama.net

High|ander

Member

From: Skövde, Sweden

Registered: 2005-10-28

Posts: 188

Website

Re: C and fork()

Hello!

execl("/usr/bin/mpg123","mpg123", "file.mp3");

@+

Changed to your code, and it worked, thanks.

After reading the API doc on execl() I saw my mistake.

---

When death smiles at you, all you can do is smile back!
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srimalik

Member

Registered: 2007-09-16

Posts: 65

Re: C and fork()

Instead of using full path, you can use the execlp function it will search the executable in the PATH environment variable.

-Sri