How to handle inputs in a C shell program during exec

Question

I am currently writing my own shell program. This simple shell can just execute commands.

When executing commands like vi or calc which require input from the terminal , the command is getting executed and is waiting for the input from the user. But I am unable to give any input on the screen.

How should the input be handled during the fork and exec.

Here is the piece of code which is executing commands:

    if((pid = fork()) < 0)
    {
            perror("Fork failed");
            exit(errno);
    }
    if(pid == 0)
    {
            // Child process
            if(execvp(arguments[0], arguments) == -1)
            {
                    child_status = errno;
                    switch(child_status)
                    {
                            case ENOENT:
                                    printf(" command not found \n");
                                    break;
                    }
                    exit(errno);
            }
    }
    else
    {
            // parent process
            int wait_stat;
            if(waitpid(pid , &wait_stat, WNOHANG) == -1)
            {
                    printf(" waitpid failed \n");
                    return;
            }
    }

} ~

Thanks,

msw · Accepted Answer · 2010-06-08 18:37:34Z

3

The WNOHANG is causing the parent process not to wait and therefore (depending on platform) the child process will be detached from terminal IO or die.

Remove the WNOHANG.

answered Jun 8, 2010 at 18:37

msw

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