Init. RC syntax

1. Set Device Permissions during init

The init executable file is the first user space program run by the Android system. It runs as a daemon.

2. Content in init. RC

Use the startup script init. RC, init STARTUP script path: System/CORE/rootdir/init. RC can perform some simple initialization operations during system initialization, init. the RC Script is directly installed in the root file system of the target system and parsed by the init executable program.

Init. RC is a STARTUP script executed after init is started. Its Syntax mainly includes the following:

Commands: Command

Actions: Action

Triggers: triggers

Services: Service

Options: Options

Properties: Properties

For the keyword of the init script, refer to the system/CORE/init/keyword. h file of the INIT process.

Commands: commands are some basic operations.

Export path/sbin:/vendor/bin:/system/sbin:/system/bin:/system/xbin

Mount yaffs2 MTD @ system/System

Mount yaffs2 MTD @ system/system Ro remount

Mount yaffs2 MTD @ userdata/Data nosuid nodev

Mount yaffs2 MTD @ Cache/cache nosuid nodev

These commands are parsed In the init executable program, and then relevant functions are called for implementation.

Actions: Action, which indicates a series of commands. It is usually called in triggers trigger conditions, and the form of action and trigger conditions.

On <trigger>

<Command>

On init

Export path/sbin:/vendor/bin:/system/sbin:/system/bin:/system/xbin

Init indicates a trigger condition initialization process. After this trigger event occurs, setting environment variables and creating directories is called an action.

The properties attribute is some values used in the system and can be set and read.

In the startup script, attributes are used as follows:

Setprop Ro. foreground_app_mem 2048

Setprop Ro. visible_app_mem 3072

On Property: RO. Secure = 0

Start Console

On property can be used to determine attributes. The attributes here are consistent throughout the Android system.

Services Service, which usually starts an executable program. The options option is the additional content of the service, used in combination with the service.

For example, start the phone process RIL-daemon and boot animation services.

Service RIL-daemon/system/bin/rild

Socket rild stream 660 root radio

Socket rild-Debug stream 660 Radio System

User Root

Group radio cache Inet MISC audio sdcard_rw

Service bootanim/system/bin/bootanimation

User graphics

Group graphics

Disabled

Oneshot

RIL-daemon and bootaim indicate the service name,/system/bin/rild and system/bin/bootanimation indicate the path of the executable program to be executed by the Service.

The oneshot option indicates that the service is started only once. If the oneshot option is not available, the executable program will always exist. If the executable program is killed, it will be restarted, RIL-daemon is a daemon. If it exits, it needs to be restarted. Therefore, it does not use the oneshot; bootaim boot animation, which is executed only once. Therefore, oneshot is added.