ANSI C - Execute Process, Wait, Delete File

Question

I am trying to execute LP to print a PDF document and wait for it to exit. After it exists i am trying to delete the file with unlink();

However the wait finishes even before execv execute LP. I am not quite sure how to handle this and why the wait isn't waiting till execv finishes.

Is there any other way to accomplish this?

        if(fork())
        {
            fprintf(stderr, "Executing command %s %s", "/usr/bin/lp", homedir);
            char *const parmList[] = {"/usr/bin/lp", homedir, (char *)0};
            execv("/usr/bin/lp", parmList );

        }else
        {
            int pid, status;
            fprintf(stderr, "Wait\n");
            pid = wait(&status);
            fprintf(stderr, "Finished waiting.\n");
            unlink(homedir);
        }

When executing the above code the ouput would look like this:

Wait
Finished waiting.
Executing command /usr/bin/lp /home/user/Docs/test.pdf
/usr/bin/lp: Error - unable to access "/home/user/Docs/test.pdf" - No such file or directory

Answer 1

fork()在子进程中返回零，在父进程中返回正值（假设fork成功），而wait(...)仅在父进程中有意义，因此您需要交换if的内容else块。