I'm appending init.rc in Android root with:
service logcat /system/bin/logcat -v long -f /mnt/sdcard/logcat.log
This solution doesn't generate any logs. The logcat.log file doesn't exist.
How can i start gathering logcat output through init.rc ?
A couple of things that could be causing problems above:
1. you defined your service to be called logcat. That looks awfully close to what might be a reserved/pre-existing name. I would choose a more distinguished service name.
2. there is no explicit start trigger for the service, hence its entirely dependent on the context in which its defined (i.e. which init phase). Pick the wrong phase (i.e. too early) and /mnt may not even exist.
3. the service will by default be running as root and thus the logcat.log file will be rw only by root. Not good to run processes as root. And not good to force readers to be root in order to read the log file.
Here the approach I've used to achieve what you're looking to do.
Problem: Ordinarily, Android log messages remain in the kernel’s (volatile) memory only and thus doesn’t survive across reboots.
Solution: To retain those log messages across reboots requires them to be written to persistent storage (i.e. the filesystem). The following code defines such a service that is started by Android during init.
Step 1, define a service that the Android init process will spawn to do this activity. This goes in init.rc.
service persistentLogging /system/bin/logcat -r 1024 -n 9 -v threadTime -f /cache/logs/log
user system
group system log
disabled
Notes about the above:
it creates a service called persistentLogging (that will be referred to in the second step below) by the start trigger.
it requests logcat to do a rolling log file (consisting of 10 files / 1Mb each) in directory - /cache/logs (i.e. log, log.1, log.2, … log.9). Adjust to suit your needs.
the service is to run as system user. This means the log file will be read+write only by system. If your app has system privileges then you’ll be able to read the log file. I’ve also defined the service to be in the log group too since that seems appropriate although since the files are not readable by group its a moot point.
the service is initially disabled. It will be started by a trigger defined below
the service is NOT oneshot. Hence, should it die, Android will attempt to restart it.
Step 2, define a trigger for starting the service. This also goes in your init.rc file.
on post-fs
mkdir /cache/logs 0775 system log
start persistentLogging
Notes about the above:
the commands are triggered during the ‘post-fs’ phase so that they occur after filesystem partitions have been mounted and when other system directories are having their permissions changed. Ideally, this service should start as late as possible because its not important or used by any other start-up activity.
the trigger first creates the target directory before starting the service. Remember the mkdir command syntax is defined by the init.rc language. In Android this syntax is not a sh syntax eventhough it looks a lot like it.
eventhough the above logging service doesn’t start until the post-fs phase of init, it will nevertheless dump all logging information since the beginning of kernel's startup as these log messages are already in the kernel buffers and this logging service is merely copying those messages to a file.
although both code fragments above ultimately need to appear in init.rc file, it is more maintainable if those additions are made to the init.${ro.hardware}.rc file defined for the device. e.g. init.freescale.rc which is automatically included by init.rc.
If we need to start the logcat and collect all the log buffers after on post-fs-data/boot completed from init.rc you can use below code in init.rc file.
on property:dev.bootcomplete=1
start logging
on post-fs-data
start logging
service logging /system/bin/logcat -b all -v threadTime -f /data/directory_name/log -r 100000 -n 9
user system
group root system log
disabled
Related
I'm using the RootTools library, and I need to execute two commands. The first one runs a binary, the second sends SIGINT to it, to kill it.
RootTools (as far as I know) can only have one root shell open at a time, so commands can only be executed one by one. This is a problem, because I have no way to stop my binary after I've ran it.
How can I do any of the following things?
Execute two commands at once, so I can run my kill command when the binary is running
Send SIGINT to my native process some other way (e.g. with a RootTools function)
I need to use RootTools because it's the only way for me to read standard output from my program. If there's another way to do that, though, please comment.
Do you think you can concat the commands?
Let's say I want to launch a find command, but if it takes 5 seconds, I want it to stop:
find / & sleep 5 && kill $!
We can get a better suited one liner, too (i.e. ignore standard error, kill only if needed etc.).
You could also just store the PID and kill it later (be careful, if the daemon stopped to run, his PID can be reused by the OS):
run the daemon in a root shell
my-daemon >/dev/null & echo "PID: $!"
parse the output in Java and store the PID (SharedPreferences?)
var pid = outputLine.split(" ")[1]
later on, stop the daemon with a root shell
kill <pid>
I'm following the guide to specify exclusions from full backups but running into a crash when I try and test it.
$ adb shell bmgr fullbackup <PACKAGE>
Works fine - files are excluded as expected.
I clear data then run:
$ adb shell bmgr restore <PACKAGE>
The restore works fine but then the next time I try and run the app I'm getting a ClassCastException:
Caused by: java.lang.ClassCastException: android.app.Application cannot be cast to com.domain.app.MyCustomApplicationClass
It appears that for some reason there is an instance of my application but it's not an instance of the custom application class as specified in the manifest.
Running the app a second time works fine and I can verify that all data was correctly restored.
I am testing this on a debug build and would like to try and resolve this error before pushing the latest changes to production.
The usual cause of this is inducing a manual restore "the wrong way." This is very poorly documented, I'm afraid, but there are different ways of invoking "bmgr restore", one of which will cause exactly the problem you describe.
(The problem, specifically, is that full-data backup/restore operations currently require that the app be launched with neither its content providers nor any app-defined Application subclass instantiated; instead, you run with a base-class Application instance. Trying to cast back to your declared subclass throws ClassCastException as you might imagine.)
In the normal course of things, your app is killed following restore. HOWEVER, if you trigger the restore like this:
adb shell bmgr restore PACKAGE
this does not happen. That particular invocation syntax runs a "my app wants to restore its data 'live' right now; do not kill me before or after" code path, the one that you get via BackupManager.requestRestore(). In this code path the app is intentionally not killed following restore. It's an artifact of the time when key/value was the only backup/restore paradigm, and in that paradigm there are no such Application subclass issues etc.
You need to make sure that when you trigger a restore via bmgr, you are using the full syntax:
adb shell bmgr restore TOKEN PACKAGE
This syntax invokes the complete restore-at-install code path, the one that will tear down your app following the restore specifically to avoid trying subsequent execution with a base-class Application.
'TOKEN' is the identifier of the dataset containing the data you wish to restore. If you are using the local debugging transport, then TOKEN is always "1". If you are using cloud backup, then it will be the device's own current backup dataset identifier if there is one, or the ancestral dataset if the device has not generated one itself. You can see these in the output of
adb shell dumpsys backup | egrep 'Current:|Ancestral:'
The dataset's identifying TOKEN is the hex string given there.
Been testing the new Android 6 auto backup/restore function, and run into a problem with my app crashing immediately after a restore. Further investigation revealed that the Application.onCreate() initialization method was not being called before the main Activity.onCreate() method. This strikes me as a likely bug in the new autorestore logic. But I thought I would ask for advice here before reporting it as an official bug.
The sequence of events I go through is
Run the app, always open a main activity window.
Force a backup of app data by entering
adb shell bmgr fullbackup net.anei.cadpage
Use the app manager to force close the app and to clear all app and cache data
Restore app information with
adb shell bmgr restore
Manually launch the app
Resulting logs show that the Activity.onCreate() method is called before the Application.onCreate() is. The app crashes because some critical initialization was not performed by the Application.onCreate() method.
Is there something obvious that I am missing???
FWIW, launching the app a second time after the crash works perfectly.
It's actually intentional, though intrusive.
For full-data backup and restore operations, the package is launched with a base class Application instance, not your manifest-declared subclass. This is because, unfortunately, many apps open files or databases via Application subclasses, and this blocks the ability of the backup machinery to correctly read/write the underlying files. Similarly, your app's content providers are not automatically instantiated for full-data backup/restore operations. The app process is then destroyed following the operation, because of course your app cannot continue to run normally without its expected Application subclass or content providers.
You also don't say exactly what command you're using to perform a test restore, but I suspect you're using the bmgr command with this syntax:
adb shell bmgr restore PACKAGE
This doesn't do what you expect. In particular, it invokes the code path that happens when your app calls BackupManager.requestRestore(observer). In this specific code path, the app is NOT shut down following the restore operation, because the app has asked to observe the operation itself. This means that you're left with the app process still running but with a base class Application. It's a power-user API that is pretty much only safe when the app uses the original key/value backup API. You need to test instead using the other bmgr syntax:
adb shell bmgr restore TOKEN PACKAGE
where TOKEN is the identifier for which dataset should be used. At least on the most recent versions of the OS you can see the current and ancestral dataset tokens in the output of adb shell dumpsys backup.
This all needs to be better documented and made less surprising.
Subclassing Application is generally discouraged; this is one reason. Try to use your own lazy-init statics instead of subclassing Application.
In order to execute a script on Android (Samsung Note 10.1 (N8010), 4.4.2) at boot I added the following to the end of the init.rc (unpacking/repacking the boot.img) to have it run as a service:
service test /system/bin/test_script.sh
class main
oneshot
The script looks like this:
#!/system/bin/sh
mkdir /sdcard/test_directory
It is eventually supposed to do something else, but for testing I kept it simple. Permissions are 0755.
The problem though is that the directory /sdcard/test_directory is not being created, which leads me to believe that the service is never being started, i.e, the script is never being executed.
I've already tried numerous things mentioned in other threads.
E.g., adding the line user root to the service, rebooting multiple times (since apparently a service is not being started after booting the device right after flashing the boot.img) or putting the script in different folders like /system/etc/ or /data/local/tmp.
Any idea what could be the problem?
Is it possible to somehow monitor whether the service is actually being started (maybe it is, but the problem lies within the script)?
Is there maybe even a better way to executing a script at boot (device does not have init.d support and I don't want to use an app like Unversal Init.d)?
EDIT:
Don't know why, but it works now.
Moved the script around multiple times, ended up putting it under /data and removing the file extension. Also added some more lines to the script like mkdir /data/local/tmp/test_directory. The directory under /sdcard is not being created though (maybe a permission problem?). Probably the reason, why I thought the script had not been executed, if it has been before.
Question remaining: is there a way to monitor whether a service is actually being started?
first time poster here. I have a problem with android. I have cron daemon set up to run a script every once and a while. This script has alarms built in to it that trigger when the script fails or succeeds. The alarms use "am" commands to activate actions on some APKs (one wakes the device, the other plays music and or vibrates).
The script works fine. However, when it is called from the crond it behaves abnormally. dmesg shows init killed the process as per this bit of code:
svc = service_find_by_pid(pid);
if (!svc) {
ERROR("untracked pid %d exited\n", pid);
Obviously my script is not in the init.rc file, nor is crond for that matter, as a service (my phone is locked/reloads init.rc from ramdisk every boot). Is there a manner of fixing this problem without editing the init.rc?
this walkthrough seems like it had you in mind:
http://howto.ccroms.net/howto/cron
As I have always wanted an actual cron installation on my phone, I
worked on patching vixie-cron for just that. Below are the tales of my
adventures: