Preface
In the process of Android source code analysis, we often see ("xxx") and getenv ("xxx") and ("xxx") obtaining the environment variable values of the Android system. The focus of this article is not to analyze the code calling logic, but to explain how to add/view system environment variables in the Android development source code environment and in the Android terminal environment. Don't say much nonsense!
1. Add environment variables in the Android source code environment
Children's boots who have experience in Linux development should know that adding environment variables is usually displayed through export and then echo, and the same is true in Android. Through global search, we found that the default file set by the Android source code environment variable is in system/core/rootdir/. This does not mean that it can only be added in this rc. In fact, it is OK to add it in other rcs at the appropriate triggering time. The file under my source code is as follows:
# set up the global environment on init export ANDROID_BOOTLOGO 1 export ANDROID_ROOT /system export ANDROID_ASSETS /system/app export ANDROID_DATA /data export ANDROID_STORAGE /storage export EXTERNAL_STORAGE /sdcard export ASEC_MOUNTPOINT /mnt/asec export BOOTCLASSPATH %BOOTCLASSPATH% export SYSTEMSERVERCLASSPATH %SYSTEMSERVERCLASSPATH% %EXPORT_GLOBAL_ASAN_OPTIONS% %EXPORT_GLOBAL_GCOV_OPTIONS%
So if we want to add environment variables, it is OK. We won’t actually operate it here. If you are interested, you can operate it yourself.
2. View and modify environment variables in Android terminal
Viewing and modifying environment variables in the Android terminal must be through adb. Let’s actually do it below.
2.1 View system environment variables
Here we still have to borrow export and echo commands, and the operation is as follows:
λ adb shell msm8953_64:/ # export ANDROID_ASSETS ANDROID_BOOTLOGO ANDROID_DATA ANDROID_ROOT ANDROID_SOCKET_adbd ANDROID_STORAGE ASEC_MOUNTPOINT BOOTCLASSPATH DOWNLOAD_CACHE EXTERNAL_STORAGE HOME HOSTNAME LOGNAME PATH SHELL SYSTEMSERVERCLASSPATH TERM TMPDIR USER msm8953_64:/ # echo $ANDROID_BOOTLOGO 1 msm8953_64:/ # echo $ANDROID_DATA /data msm8953_64:/ #
2.2 Set system environment variables
Here we still have to borrow export and echo commands, and the operation is as follows:
130|msm8953_64:/ # export HELLOWORD=Android msm8953_64:/ # echo $HELLOWORD Android msm8953_64:/ #
summary
Okay, the chapter on Android getting and setting system environment variables has come to an end. After learning this trick, we can directly view the relevant values of system environment variables through the adb command in the analysis of Android source code, so that we can analyze it easily. See you all!
Summarize
This is the end of this article about Android obtaining and setting system environment variables. For more related content about Android obtaining and setting system environment variables, please search for my previous articles or continue browsing the related articles below. I hope everyone will support me in the future!