Question

我正在编写自己的unix shell。当我尝试CTRL-C这样的事情时，我的新子进程正在后台启动/运行。但是当我在母进程（我的shell）中点击CTRL-C时，它会关闭firefox（我的后台（-child）进程）。我不想用WIFEXITED(status)关闭bg子进程。它应该什么都不做（它只应该杀死fg进程，如果除了我的shell之外还有其他东西）。

我已阅读void signal_handler(int signum) { switch (signum) { case SIGINT: // CTRL-C cout << " [caught SIGINT]" << pid << endl; if(pid != 0) { kill(pid, SIGINT); } break; case SIGTSTP: // CTRL-Z cout << " [caught SIGTSTP]" << endl; if(pid != 0) { kill(pid, SIGTSTP); } break; case SIGCHLD: while((waitpid(pid,0, WNOHANG | WUNTRACED))>0) { cout << "[" << pid << "] done" << endl; } break; default: break; } return; }，但我真的不知道如何使用它。

我的信号处理程序：

// some names of variables were changed to show it to you more readable.

signal(SIGINT, signal_handler);
signal(SIGTSTP, signal_handler);
signal(SIGCHLD, signal_handler);

if (input == "fg" || input == "bg") {
        if (input == "fg") {
            pid = inputPid(input);                  //function to get pid when user types something like fg 1234 (foreground pid 1234)
            kill(pid, SIGCONT);                     // SIGCONT -> continue
            cout << "[" << inputPid(input) << "]" << endl;
            waitpid(pid, &status, WUNTRACED);       // WUNTRACED -> return if a child has stopped
            pid = 0;
        } else if (input == "bg") {
            bgPids.push_back(pid);
            kill(pid,SIGCONT);
        }
    } else if(input == "background") {
        cout << "PIDs in Background: ";
        for(int i = 0; i < bgPids.size(); i++) {    // vector which gets all background pids
            cout << "[" << bgPids[i] << "] ";
        }
        cout << endl;
    } else {
        if ((pid = fork()) < 0) {
            cout << "Error" << endl;
            exit(1);
        } else if (pid == 0) {                      // child

            signal(SIGINT, SIG_DFL);    
            signal(SIGTSTP, SIG_DFL);
            signal(SIGCHLD, SIG_DFL);
            setpgid(0, getpid());               
            execvp(arguments[0], &arguments[0]);
            cout << "Error" << endl;
            exit(1);
        } else if (checkIfBackground(inputNew) == false) {  // mother
            pid_t pid_r;
            if (waitpid(pid, &status, WUNTRACED) < 0) {
                cout << "Error" << endl;
            }
        } else { // when user types argument& or argument &
            bgPids.push_back(pid);
            cout << "Prozess is in background!" << endl;
            if(WIFEXITED(status)) {
                cout << "bg exited" << status << endl;
            }
        }
    }
}

这就是我开始一个过程的方式：

FILE*

SIGTSTP杀死后台进程

0 个答案: