---
id: cf7cfd71-d2ac-4f5a-a175-808ef410a339
slug: linux-process-learning-2
title: Linux 进程学习 二
summary: ""
status: published
tags: []
cover: ""
version: 1
slug_source: manual
slug_locked: true
published_at: "2022-10-16T16:13:33+08:00"
created_at: "2022-10-16T16:13:33+08:00"
updated_at: "2026-01-07T18:10:43+08:00"
---

## 创建进程
在 Linux 中每个进程都是父进程创建的，Linux 启动时会创建init 进程，这是系统的第一个进程，其 PID 为 1。
在 C 语言中，我们可以用fork函数创建新的进程：
```c
#include <unistd.h>
pid_t fork(void);
```
- If fork() returns a negative value, the creation of a child process was unsuccessful.
- fork() returns a zero to the newly created child process.
- fork() returns a positive value, the process ID of the child process, to the parent. The returned process ID is of type pid_t defined in sys/types.h. Normally, the process ID is an integer. Moreover, a process can use function getpid() to retrieve the process ID assigned to this process.

也就是：
> On success, the PID of the child process is returned in the
       parent, and 0 is returned in the child.  On failure, -1 is
       returned in the parent, no child process is created, and errno is
       set to indicate the error.

也就是：
- 返回负数，创建失败
- 返回 0 ，就是子进程，它永远返回 0
- 返回大于 0 的整数，这是父进程，它会返回子进程的pid

## 终止进程