void new_init_action(int action, const char *command, const char *cons) //函数开始
{
/*
先介绍init_action结构体...>terminal, cons) == 0))
{a->action = action;
return;}
/*更新last,等于上一个init_action 结构体...(2.1) 然后逐步反推代码:
if (file == NULL) {
/*ID为空, runlevels忽略, action= ctrlaltdel, process= reboot...*/
new_init_action(CTRLALTDEL, "reboot", "");
/*ID为空, runlevels忽略, action= shutdown, process=..., runlevels忽略, action= restart, process= init */
new_init_action(RESTART, "init", "");
/*ID为空, runlevels