android 初始化 脚本 Android init language与init.rc初始化脚本

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参考: android源码目录里的system/core/init/readme.txt.

Android系统里以*.rc为扩展名为系统初始化脚本，脚本里就是使用安卓初始化语言.

语句都是一行为一条语句，没有符号分隔. 语句里的每个词用空格隔开.

如: service ueventd /sbin/ueventd

备注语句以符号”#”作为注释.

语言基本上分为4个块: Actions Commands Services 和 Options.

每个Actions和Services关键词开始的语句作为一个新的区块.

Commands和Options就是属于就近的Actions或Services块.

如:

Actions的形式:

Services的形式:

[]*

rc文件里实例:

system/bin/logd

socketlogdstream0666logdlogd

socketlogdrseqpacket0666logdlogd

socketlogdwdgram0222logdlogd

system

system-background/tasks

s0

#Actions

#on

#Setinitanditsforkedchildren'soom_adj.

write/proc/1/oom_score_adj-1000

#Setthesecuritycontextof/adb_keysifpresent.

每个rc文件里又可以包含其它rc文件:

import/init.environ.rc

import/init.usb.rc

import/init.${ro.hardware}.rc

import/init.usb.configfs.rc

import/init.${ro.zygote}.rc

import/init.trace.rc

Actions里常用的trigger有:

onearly-init

oninit

onlate-init

onpost-fs

onboot

onproperty:sys.init_log_level=*//在设置属性值时触发

oncharger

onproperty:sys.powerctl=*

常用的Commands有://参考system/core/init/keywords.h

Startbootchartingifconfigured(seebelow).

isincludedinthedefaultinit.rc.

mode>

Changefileaccesspermissions.

Changefileownerandgroup.

Startallservicesofthespecifiedclassiftheyare

notalreadyrunning.

Stopanddisableallservicesofthespecifiedclassiftheyare

Stopallservicesofthespecifiedclassiftheyare

withoutdisablingthem.Theycanberestarted

usingclass_start.

towrite,butusefulforbinary/large

ofdata.

name>

Setthedomainname.

enableintoanenabledoneasiftheservicedidnot

Iftheserviceissupposedtoberunning,itwillbestartednow.

whenthebootloadersetsavariablethatindicatesaspecific

whenneeded.E.g.

onproperty:ro.boot.myfancyhardware=1

enablemy_fancy_service_for_my_fancy_hardware

[[]*]]--[]*

andexecutecommandwiththegivenarguments.Thecommandstarts

after"--"sothatanoptionalsecuritycontext,user,andsupplementary

groupscanbeprovided.Noothercommandswillberununtilthisone

canbea-todenotedefault.

export

Settheenvironmentvariableequaltointhe

globalenvironment(whichwillbeinheritedbyallprocesses

afterthiscommandisexecuted)

name>

Setthehostname.

interface>

interfaceonline.

importParseaninitconfigfile,extendingthecurrentconfiguration.

path>

Installthemoduleat

from/system,/vendor,etcetera.

isincludedinthedefaultinit.rc.

when/datahasbeendecrypted.

isincludedinthedefaultinit.rc.

level>

Setsthekernellogleveltolevel.Propertiesareexpandedwithin.

path>[mode][owner][group]

Createadirectoryat,optionallywiththegivenmode,owner,and

Ifnotprovided,thedirectoryiscreatedwithpermissions755and

bytherootuserandrootgroup.Ifprovided,themode,ownerandgroup

updatedifthedirectoryexistsalready.

onthegivenfs_mgr-formatfstab.

mount[]*[]

tomountthenameddeviceatthedirectorymaybeoftheformmtd@nametospecifyamtdblock

byname.

sinclude"ro","rw","remount","noatime",...

include"barrier=1","noauto_da_alloc","discard",...as

string,eg:barrier=1,noauto_da_alloc

torespondtochangestothe

"sys.powerctl"systemproperty,usedtoimplementrebooting.

Likestop,butdoesn'tdisabletheservice.

[]*

tothesecuritycontextspecified

[]*

tothe

to.Propertiesareexpanded

.

withthevalue.verifiedpropertiesusedbyadbremounttsetthemdirectlyitself.

wait[]

fortheexistenceofthegivenfileandreturnwhenfound,

orthetimeouthasbeenreached.Iftimeoutisnotspecifiedit

defaultstofiveseconds.

path>

Openthefileatandwriteastringtoitwithwrite(2).

Ifthefiledoesnotexist,itwillbecreated.Ifitdoesexist,

areexpandedwithin.

Services里常用的options有:

isadevice-criticalservice.Ifitexitsmorethanfourtimesin

intorecoverymode.

notautomaticallystartwithitsclass.

byname.

Settheenvironmentvariabletointhelaunchedprocess.

[[[]]]

andpass

tothelaunchedprocess.mustbe"dgram","stream"or"seqpacket".

andgroupdefaultto0.

'seclabel'istheSELinuxsecuritycontextforthesocket.

totheservicesecuritycontext,asspecifiedbyseclabelor

ontheserviceexecutablefilesecuritycontext.

tousernamebeforeexec'ingthisservice.

toroot.(???probablyshoulddefaulttonobody)

ifyourprocessrequireslinuxcapabilitiesthenyoucannotuse

in-processwhile

andthendroptoyourdesireduid.

group[]*

togroupnamebeforeexec'ingthisservice.Additional

tosetthe

oftheprocess(viasetgroups()).

toroot.(???probablyshoulddefaulttonobody)

to'seclabel'beforeexec'ingthisservice.

forusebyservicesrunfromtherootfs,e.g.ueventd,adbd.

onthesystempartitioncaninsteadusepolicy-definedtransitions

ontheirfilesecuritycontext.

Ifnotspecifiedandnotransitionisdefinedinpolicy,defaultstotheinitcontext.

Donotrestarttheservicewhenitexits.

classclassnamefortheservice.Allservicesina

classmaybestartedorstoppedtogether.Aservice

isintheclass"default"ifoneisnotspecifiedviathe

classoption.

whenservicerestarts.

'spidtothegivenfileswhenitforks.Meantfor

实现直接使用root用户进入终端, 修改android/out/target/product/tulip-p1/root/init.rc :

console/system/bin/sh

classcore

console

#usershell

#groupshelllog

#seclabelu:r:shell:s0

//备注使用shell用户进入终端. 会默认使用root用户操作

实现系统进入后执行自定义的脚本 :修改android/out/target/product/tulip-p1/root/init.rc , 增加内容:

servicestart_mytest/system/bin/mytest.sh

onproperty:sys.boot_completed=1

在android/out/target/product/tulip-p1/system/bin目录下，增加mytest.sh, 内容:

#!/system/bin/sh

echo"mytest...!">/dev/ttyS0

echo"mytest...!">/dev/ttyS0

echo"mytest...!">/dev/ttyS0

echo"mytest...!">/dev/ttyS0

echo"mytest...!">/dev/ttyS0

echo"mytest...!">/dev/ttyS0

echo"mytest...!">/dev/ttyS0