yarnom
f0b50d13ea
Add Go/Postgres admin APIs, Angular admin UI, manual build flow, asset uploads, markdown import/export, configurable slug generation, and the Yar reading theme. Exclude local docs and generated development artifacts from version control.
1.4 KiB
1.4 KiB
| id | slug | title | summary | status | tags | cover | version | slug_source | slug_locked | published_at | created_at | updated_at |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| cf7cfd71-d2ac-4f5a-a175-808ef410a339 | linux-process-learning-2 | Linux 进程学习 二 | published | 1 | manual | true | 2022-10-16T16:13:33+08:00 | 2022-10-16T16:13:33+08:00 | 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：
#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