diff --git a/C13-Linux系统编程/C13-Linux系统编程学习笔记.md b/C13-Linux系统编程/C13-Linux系统编程学习笔记.md
index f22b763..d38c883 100644
--- a/C13-Linux系统编程/C13-Linux系统编程学习笔记.md
+++ b/C13-Linux系统编程/C13-Linux系统编程学习笔记.md
@@ -968,4 +968,142 @@ struct rlimit {
     rlim_t rlim_cur;  /* soft limit */
     rlim_t rlim_max;  /* hard limit */
 };
-```
\ No newline at end of file
+```
+
+
+# 进程基本知识
+
+已经进入**多进程**阶段
+
+## 进程标识符`pid`
+类型`pid_t`，传统意义上是一个16位有符号整型数。
+命令`ps`
+常用命令：`ps axf`，`ps aux`，`ps axm`，`ps ax -L`
+进程号是顺次向下使用
+```c
+// 返回当前进程号
+pid_t getpid(void);
+
+// 返回父进程的进程号
+pid_t getppid(void);
+```
+
+## 进程的产生
+
+`pid_t fork();`
+- 以**复制（duplicating）**当前进程的方式创建一个新进程
+- 和`setjmp`一样，执行一次，返回两次
+- 在`fork`处复制，不会从头运行
+
+`fork`后父子进程的不同之处：
+1. `fork`的返回值不一样
+2. `pid`不同
+3. `ppid`也不同
+4. 未决信号和文件锁不继承
+5. 资源利用量清0
+
+`init`进程：**1号**，是所有进程的祖先进程
+
+调度器的调度策略来决定哪个进程先执行
+
+`fflush()`的重要性
+
+```c
+/*
+ *  vfork创建的子进程只能做exec或者exit
+ *  ! 基本废弃
+ */
+pid_t vfork(void);
+```
+
+## 进程的消亡及释放资源
+```c
+// 等待进程状态发生变化
+pid_t wait(int *status); // 阻塞
+
+pid_t waitpid(pid_t pid, int *status, int options);
+
+int waitid(idtype_t idtype, id_t id, siginfo_t *infop, int options);
+
+
+wait3();
+wait4();
+```
+
+分配法和交叉分配法，90%优先选择交叉分配法。
+
+池类算法：
+上游往池子里放任务，下游三个线程从池子里取任务。
+
+## `exec`函数族
+eg. `bash`进程创建`primer`进程
+
+```c
+// exec函数族：替换当前进程的映像
+
+extern char **environ;
+
+int execl(const char *path, const char *arg, ...);
+
+int execlp(const char *file, const char *arg, ...);
+
+int execle(const char *path, const char *arg, ..., char * const envp[]);
+
+int execv(const char *path, char *const argv[]);
+
+int execvp(const char *file, char *const argv[]);
+
+```
+
+## 用户权限及组权限
+
+
+## 观摩课：解释器文件
+
+
+## `system()`函数
+
+
+## 进程会计
+
+
+## 进程时间
+
+
+## 守护进程
+
+
+## 系统日志
+
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diff --git a/C13-Linux系统编程/process_basic/ex.c b/C13-Linux系统编程/process_basic/ex.c
new file mode 100644
index 0000000..6d85cdd
--- /dev/null
+++ b/C13-Linux系统编程/process_basic/ex.c
@@ -0,0 +1,28 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+/**
+ * @brief    data +%s
+ * @details
+ *
+ * @param    argc
+ * @param    argv
+ * @return  int
+ */
+int main(int argc, char **argv)
+{
+    puts("Begin!");
+    fflush(NULL);   // !!!
+
+    execl("/bin/date", "date", "+%s", NULL);
+    // NULL 作为参数列表的结束标志
+
+    // !! 如果不出错，不会到这里
+    perror("execl()");
+    exit(1);
+
+    puts("End!");
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/C13-Linux系统编程/process_basic/few.c b/C13-Linux系统编程/process_basic/few.c
new file mode 100644
index 0000000..f1a6c38
--- /dev/null
+++ b/C13-Linux系统编程/process_basic/few.c
@@ -0,0 +1,42 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+/**
+ * @brief    few: folk, execl, wait
+ * @details
+ *
+ * @param    argc
+ * @param    argv
+ * @return  int
+ */
+int main(int argc, char **argv)
+{
+    pid_t pid;
+
+    puts("Begin!");
+
+    fflush(NULL);
+
+    pid = fork();
+    if (pid < 0)
+    {
+        perror("fork()");
+        exit(1);
+    }
+
+    if (0 == pid)   // child
+    {
+        execl("/bin/date", "date", "+%s", NULL);
+        perror("execl()");
+        exit(1);
+    }
+
+    wait(NULL);
+
+    puts("End!");
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/C13-Linux系统编程/process_basic/fork1.c b/C13-Linux系统编程/process_basic/fork1.c
new file mode 100644
index 0000000..5b06406
--- /dev/null
+++ b/C13-Linux系统编程/process_basic/fork1.c
@@ -0,0 +1,40 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int main(int argc, char **argv)
+{
+    pid_t pid;
+
+    /*
+     *  如果 ./fork1 > /tmp/out
+     *  begin会由父进程输出两次
+     *  缓冲问题
+     *  文件时全缓冲
+     */
+    printf("[%d]Begin!\n", getpid());
+
+    fflush(NULL);   // !!! 在fork之前刷新该刷新的流
+
+    pid = fork();
+    if (pid < 0)
+    {
+        perror("fork()");
+        exit(1);
+    }
+
+    if (pid == 0)   // child
+    {
+        printf("[%d]Child is working!\n", getpid());
+    }
+    else   // parent
+    {
+        printf("[%d]Parent is working!\n", getpid());
+    }
+
+    printf("[%d]End!\n", getpid());
+
+    // getchar();
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/C13-Linux系统编程/process_basic/myshell.c b/C13-Linux系统编程/process_basic/myshell.c
new file mode 100644
index 0000000..87a79fb
--- /dev/null
+++ b/C13-Linux系统编程/process_basic/myshell.c
@@ -0,0 +1,41 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int main(int argc, char **argv)
+{
+    while (1)
+    {
+        prompt();
+
+        getline();
+
+        parse();
+
+        if (内部命令)
+        {
+            ;
+        }
+        else   // 外部命令
+        {
+            fork();
+            if (< 0)
+            {
+                ;
+            }
+
+            if (0 ==)   // child
+            {
+                execXX;
+                perror();
+                exit(1);
+            }
+            else   // parent
+            {
+                wait();
+            }
+        }
+    }
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/C13-Linux系统编程/process_basic/primer0.c b/C13-Linux系统编程/process_basic/primer0.c
new file mode 100644
index 0000000..98c9638
--- /dev/null
+++ b/C13-Linux系统编程/process_basic/primer0.c
@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#define LEFT  30000000
+#define RIGHT 30000200
+
+/**
+ * @brief    求质数（单机版）
+ * @details
+ *
+ * @param    argc
+ * @param    argv
+ * @return  int
+ */
+int main(int argc, char **argv)
+{
+    int i, j, mark;
+
+    for (i = LEFT; i <= RIGHT; i++)
+    {
+        mark = 1;
+        for (j = 2; j < i / 2; j++)
+        {
+            if (i % j == 0)
+            {
+                mark = 0;
+                break;
+            }
+        }
+
+        if (mark)
+            printf("%d is a primer\n", i);
+    }
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/C13-Linux系统编程/process_basic/primer1.c b/C13-Linux系统编程/process_basic/primer1.c
new file mode 100644
index 0000000..a8c67b2
--- /dev/null
+++ b/C13-Linux系统编程/process_basic/primer1.c
@@ -0,0 +1,53 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#define LEFT  30000000
+#define RIGHT 30000200
+
+/**
+ * @brief    求质数（多进程版）
+ * @details
+ *
+ * @param    argc
+ * @param    argv
+ * @return  int
+ */
+int main(int argc, char **argv)
+{
+    int   i, j, mark;
+    pid_t pid;
+
+    for (i = LEFT; i <= RIGHT; i++)
+    {
+
+        pid = fork();
+        if (pid < 0)
+        {
+            perror("fork()");
+            exit(1);
+        }
+
+        if (pid == 0)   // child
+        {
+            mark = 1;
+            for (j = 2; j < i / 2; j++)
+            {
+                if (i % j == 0)
+                {
+                    mark = 0;
+                    break;
+                }
+            }
+            if (mark)
+                printf("%d is a primer\n", i);
+
+            sleep(1000);   // * 让父进程先结束
+            exit(0);       // ! 退出子进程
+            // ! init 在孤儿进程 exit 后才收尸
+        }
+    }
+
+    // sleep(1000);   // * 让子进程先结束，子进程会变成僵尸态
+    exit(0);
+}
\ No newline at end of file
diff --git a/C13-Linux系统编程/process_basic/primer2.c b/C13-Linux系统编程/process_basic/primer2.c
new file mode 100644
index 0000000..c256900
--- /dev/null
+++ b/C13-Linux系统编程/process_basic/primer2.c
@@ -0,0 +1,56 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#define LEFT  30000000
+#define RIGHT 30000200
+
+/**
+ * @brief    求质数（多进程版）
+ * @details
+ *
+ * @param    argc
+ * @param    argv
+ * @return  int
+ */
+int main(int argc, char **argv)
+{
+    int   i, j, mark;
+    pid_t pid;
+
+    for (i = LEFT; i <= RIGHT; i++)
+    {
+
+        pid = fork();
+        if (pid < 0)
+        {
+            perror("fork()");
+            exit(1);
+        }
+
+        if (pid == 0)   // child
+        {
+            mark = 1;
+            for (j = 2; j < i / 2; j++)
+            {
+                if (i % j == 0)
+                {
+                    mark = 0;
+                    break;
+                }
+            }
+            if (mark)
+                printf("%d is a primer\n", i);
+
+            exit(0);   // ! 退出子进程
+        }
+    }
+
+    // int st;
+    for (i = LEFT; i <= RIGHT; i++)
+        // wait(&st);
+        wait(NULL);
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/C13-Linux系统编程/process_basic/primerN.c b/C13-Linux系统编程/process_basic/primerN.c
new file mode 100644
index 0000000..e8b72b4
--- /dev/null
+++ b/C13-Linux系统编程/process_basic/primerN.c
@@ -0,0 +1,59 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#define LEFT  30000000
+#define RIGHT 30000200
+#define N     3
+
+
+/**
+ * @brief    求质数（多进程版）
+ * @details
+ *
+ * @param    argc
+ * @param    argv
+ * @return  int
+ */
+int main(int argc, char **argv)
+{
+    int   i, j, n, mark;
+    pid_t pid;
+
+    for (n = 0; n < N; n++)
+    {
+        pid = fork();
+        if (pid < 0)
+        {
+            perror("fork()");
+            exit(1);   // ! 加入在第三次fork失败时，退出，前两次没有收尸
+        }
+
+        if (pid == 0)
+        {
+            for (i = LEFT + n; i <= RIGHT; i += N)
+            {
+
+                mark = 1;
+                for (j = 2; j < i / 2; j++)
+                {
+                    if (i % j == 0)
+                    {
+                        mark = 0;
+                        break;
+                    }
+                }
+                if (mark)
+                    printf("[%d]%d is a primer\n", n, i);
+            }
+
+            exit(0);   // ! 退出子进程
+        }
+    }
+
+    for (n = 0; n < N; n++)
+        wait(NULL);
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/C13-Linux系统编程/process_basic/sleep.c b/C13-Linux系统编程/process_basic/sleep.c
new file mode 100644
index 0000000..754a333
--- /dev/null
+++ b/C13-Linux系统编程/process_basic/sleep.c
@@ -0,0 +1,45 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+/**
+ * @brief    few: folk, execl, wait
+ * @details
+ *
+ * @param    argc
+ * @param    argv
+ * @return  int
+ */
+int main(int argc, char **argv)
+{
+    pid_t pid;
+
+    puts("Begin!");
+
+    fflush(NULL);
+
+    pid = fork();
+    if (pid < 0)
+    {
+        perror("fork()");
+        exit(1);
+    }
+
+    if (0 == pid)   // child
+    {
+        // execl("/bin/sleep", "sleep", "100", NULL);
+        execl("/bin/sleep", "httpd", "100", NULL);
+        // ! 低级木马：进程树里看到的是httpd 100
+
+        perror("execl()");
+        exit(1);
+    }
+
+    wait(NULL);
+
+    puts("End!");
+
+    exit(0);
+}
\ No newline at end of file