Android Start Analysis-init process &init.rc[turn]

init.rc Parsing and chmod changing file properties is useless

Turn from: Http://h1372865100.blog.163.com/blog/static/2104291032012929114132327/android's init.rc grammar is unique, it can be said to be a language bar.

INIT.RC syntax is divided into actions (actions), commands (Commands), Service (services), Options .

category	name	Description
Section	On	Trigger condition
Ditto..	Service	Parsing service
COMMAND	ChDir	Change the current working directory
Ditto..	Chroot	Change the location of the reference's root directory
..	Class_start	Start a service with the class name set
..	Class_stop	Stop a service that has a class name set
..	DomainName	Domain name
..	Exec	Calling programs and transferring processes
..	Export	Submit variable
..	Hostname	Host Name
..	Ifup	Activate network card
..	Insmod	Mount Module
..	Import	Introduction of configuration, such as etc under the RC files, and Java import almost
..	Mkdir	Create a Directory
..	Mount	Mount File System
..	Setkey	From the source view, should be set a command of the keyword abbreviation, such as the DomainName can be mapped to DN
..	SetProp	Set a property
..	Setrlimit	Sets the maximum number of files that can be opened by the current program to the maximum number of files that the system requires the program to open
..	Start	Start a service
..	Stop	Stop Service
..	Trigger	Not clear, is it a custom trigger.
..	Symlink	Create a symbolic link
..	Sysclktz	Set base Time
..	Wait	Wait for the file to be ready. This is a function of process scheduling in Linux
..	Write	Write something to a file or device. It's definitely not the wirte that sent the message.
..	Copy	Do not explain
..	Chown	Change owner
..	chmod	Change permissions
..	LogLevel	Log output level, below this level of output
..	Restart	Restart Service
OPTION	Capability	Ability, that is, a system of the process of a privilege control.
Ditto..	Class	Set class name
..	Console	Enable Console
..	Critical	Is the key, that is, 4 minutes to restart more than 4 times, after the reboot into the recovery mode
..	Disabled	Do not start automatically with class
..	Group	Group attribution
..	Keycodes	Don't understand.....
..	OneShot	Start only once and do not need to reboot after exiting unexpectedly
..	Onrestart	When restarting
..	Setenv	Increase environment variables
..	Socket	Request Socket Resource
..	User	User ownership
..	Ioprio	IO scheduling Priority

(Many of the attributes and command usages are not much different from the commands in Linux)

Init is a segmented (section) parsing init.rc, where you can view the definition of a keyword in keywords.h. What is the symbol of Init to parse init.rc? Combined with the content of init.rc, it can be seen that the segmented markup is marked with on and service. Here is a detailed description.

On what time?

On belongs to the behavior.

on Early-init

Executed before Init, after loading all RC files, in MIUI ROM, init.rc executes the start Ueventd in Early-init, according to the KEYWORDS.H definition, start is a command.

Here, by the way, ueventd,android in the bottom (generally refers to the driver) to notify the upper level of the event, with the UEVENT,JAVA layer through the observer mode implementation, the class used for Ueventobserver, using intent to pass The native layer is android_os_ueventobserver.cpp, using uevent.c to pass through the socket. Of course, this is the framework and the following level, the general development is not often used, not to mention these several classes have not been exposed.

On Init

Executes before the Propety properties file is loaded, before Init becomes propety service, it belongs to the init phase.

On Early-boot

Executes after the property service is started.

On boot

When boot is executed.

On Property:xxxxx=x

Executes when a property is set to the expected value.

About Init.rc, actually combine/src/system/core/init/* source code and Init.rc file look, will understand many.

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Sometimes you need to add your own added files to root, and then in init.rc modify the properties of the file found no use, I also toss a half-day, on the internet to see a post:

Create a script somewhere, for example,/system/bin/mymod.rc
#!/system/bin/sh
chmod 0777/dev/mynode

Add the following in/init.rc:
Service Mymod/system/bin/mymod.rc
OneShot

(Note that the table adds the wrong location/system/bin/, is the system directory that generates the filesystem, not the system directory under root)