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.vscode/settings.json

@@ -0,0 +1,6 @@
+{
+    "files.associations": {
+        "wait.h": "c",
+        "stat.h": "c"
+    }
+}

child_porcess_clean/clear.c

@@ -0,0 +1,50 @@
+#include <stdio.h>
+#include <signal.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <time.h>
+#include <sys/time.h>
+
+void process_clean()
+{
+    while (wait(NULL) != -1)
+    {
+        printf("child clean\n");
+    }
+
+    return 0;
+}
+int main(int argc, char *argv[])
+{
+    signal(SIGCHLD, process_clean);
+    for (int i = 0; i < 10; i++)
+    {
+        pid_t pid = fork();
+        if (pid == 0)
+        {
+            sleep(1);
+            exit(0);
+        }
+        else if (pid > 0)
+        {
+            int status;
+            // wait(&status);
+            // printf("Child %d exited with status %d\n", pid, status);
+        }
+        else
+        {
+            perror("fork");
+        }
+    }
+    int k = 5;
+    while (k--)
+    {
+        sleep(1);
+    }
+
+    return 0;
+}

child_porcess_clean/run.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+gcc -o test.bin clear.c
+./test.bin

deamon/daemon.c

@@ -0,0 +1,158 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <string.h>
+
+#define CREAT_PID_FILE_PATH "/tmp/mydaemon.pid"
+#define LOG_FILE_NAME "log.txt"
+#define SUCCESS() fprintf(stdout, "success\n")
+void daemonize(const char *cmd)
+{
+    pid_t pid, sid;
+
+    // Fork off the parent process
+    pid = fork();
+    // An error occurred
+    if (pid < 0)
+    {
+
+        fprintf(stderr, "can not creat process\n");
+        exit(EXIT_FAILURE);
+    }
+    // Success: Let the parent terminate
+    if (pid > 0)
+    {
+        exit(EXIT_SUCCESS);
+    }
+
+    // On success: The child process becomes session leader
+    if ((sid = setsid()) < 0)
+    {
+        fprintf(stderr, "can not new secion\n");
+        exit(EXIT_FAILURE);
+    }
+
+    // Catch, ignore and handle signals
+    signal(SIGCHLD, SIG_IGN);
+    signal(SIGHUP, SIG_IGN);
+    // Fork off for the second time
+    pid = fork();
+
+    // An error occurred
+    if (pid < 0)
+    {
+        fprintf(stderr, "can not creat process\n");
+        exit(EXIT_FAILURE);
+    }
+
+    // Success: Let the parent terminate
+    if (pid > 0)
+    {
+        exit(EXIT_SUCCESS);
+    }
+
+    // Set new file permissions
+    umask(0);
+
+    // Change the working directory to the root directory
+    // or another appropriated directory
+    if ((chdir("/")) < 0)
+    {
+        exit(EXIT_FAILURE);
+    }
+
+    // Open the /dev/null file
+    // open("/dev/null", O_RDWR);
+    // open("/dev/null", O_RDWR);
+
+    // Write the PID to the pidfile
+    FILE *fp;
+    fp = fopen(CREAT_PID_FILE_PATH, "w");
+    if (fp != NULL)
+    {
+        fprintf(fp, "%d\n", getpid());
+        fclose(fp);
+    }
+    else
+    {
+        fprintf(stdout, "create file error\n");
+        exit(EXIT_FAILURE);
+    }
+    fprintf(stdout,"server start...\n");
+    // Close all open file descriptors
+    int x;
+    for (x = sysconf(_SC_OPEN_MAX); x >= 0; x--)
+    {
+        close(x);
+    }
+    //  Open the /dev/null file
+    open("/dev/null", O_RDWR);
+    open("/dev/null", O_RDWR);
+    // Now we can do the tasks of the daemon
+    while (1)
+    {
+        // Your daemon code here
+        sleep(1);
+        fprintf(stdout, "Daemon is running...\n");
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    const char *cmd = "mydaemon";
+    // Check for a valid command line argument
+    if (argc < 2)
+    {
+        fprintf(stderr, "Usage: %s start|stop\n", cmd);
+        exit(EXIT_FAILURE);
+    }
+
+    // Check the command line argument
+    if (strcmp(argv[1], "start") == 0)
+    {
+        // 测试下是否已经有个进程了
+        int exit = access(CREAT_PID_FILE_PATH, F_OK);
+        if (exit == 0)
+        {
+            fprintf(stderr, "the server is exited, so safe exit\n");
+            return 0;
+        }
+        else
+        {
+            fprintf(stdout, " try to start server\n");
+        }
+        daemonize(cmd);
+    }
+    else if (strcmp(argv[1], "stop") == 0)
+    {
+        // Code to stop the daemon
+        FILE *fp;
+        pid_t pid;
+
+        fp = fopen(CREAT_PID_FILE_PATH, "r");
+        if (fp != NULL)
+        {
+
+            fscanf(fp, "%d", &pid);
+            fclose(fp);
+            kill(pid, SIGTERM);
+            remove(CREAT_PID_FILE_PATH);
+            fprintf(stdout, "server stop...\n");
+        }
+        else
+        {
+            printf(" no find the process\n");
+        }
+    }
+    else
+    {
+        fprintf(stderr, "Usage: %s start|stop\n", cmd);
+        exit(EXIT_FAILURE);
+    }
+
+    return EXIT_SUCCESS;
+}

deamon/run.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+if [ "$1" = "ps" ];then
+    ps -aux | grep test
+else 
+    gcc -o test.bin daemon.c
+    ./test.bin $1
+fi

exec/app.c

@@ -0,0 +1,6 @@
+#include <stdio.h>
+
+int main(int argc ,char *argv[]){
+    printf("app run\n");
+    return 0;
+}

exec/exec.c

@@ -0,0 +1,39 @@
+#include <stdio.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/wait.h>
+#include <sys/stat.h>
+#include <signal.h>
+extern char **environ;
+
+int main(int argc ,char *argv[])
+{
+    char pwd[1024];
+    getcwd(pwd,1024);
+    printf("master \n");
+    printf("path %s\n",pwd);
+    char path[1024];
+    snprintf(path,sizeof(path),"%s/app.bin",pwd);
+
+    char *exec_arg[]={path,NULL};
+    char *envp[] = {NULL};  
+    int err = execve(path,exec_arg,envp);
+    printf("error happen %d\n",err);
+    return 0;
+}
+ 
+
+// int main() {  
+
+//     char *args[] = {"/bin/ls", "-l", NULL};  
+//     char *envp[] = {"PATH=/bin:/usr/bin", NULL};  
+//     execve("/bin/ls", args, envp);  
+//     // 如果 execve 失败，会执行到这里  
+//     perror("execve failed");  
+
+//     return 1;  
+
+// }

exec/run.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+gcc -o app.bin ./app.c
+gcc -o test.bin ./exec.c
+./test.bin ./app.bin