app_process command in Android

本来以为存放在／systen／bin／下的monkey、input、am等adb shell命令都是二进制可执行程，偶尔cat input下，发现不是二进制文件，内容如下：# Script to start "input" on the device, which has a very rudimentary
# shell.
#
base=/system
export CLASSPATH=$base/framework/input.jar
exec app_process $base/bin com.android.commands.input.Input $*

这段脚本的作用就是通过app_process工具启动放在／system／farmework／下的input.jar 文件。我查看了下framework文件夹里面的确有input.jar文件。

What is this app_process

Although not that popular “app_process” command is used heavily in Android, for example the well know “am” script is using it. Everybody knows how to start an application from adb shell:

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am start -n yourpackagename/.activityname
However “am” is just a shell script and what stays in the base of the am script is our app_process binary:

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root@android:/ # cat /system/bin/am
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cat /system/bin/am
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# Script to start "am" on the device, which has a very rudimentary
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# shell.
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#
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base=/system
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export CLASSPATH=$base/framework/am.jar
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exec app_process $base/bin com.android.commands.am.Am "$@"
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root@android:/ #
So app_process is the binary used to start java code. All the apps, instrumentations or installations are tarted using this.

Usage … NOT:

Lets see the official usage output:

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root@android:/ # app_process
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Usage: app_process [java-options] cmd-dir start-class-name [options]
Not quite complete as usual :)