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Anybody else having trouble writing to /system while in Android 4.3? Even with adb remount executed. The weird part is I can rename files, but I can't copy. Not even to /data/local/. What changed?
Jonathan Lam's profile photoJoe Taber's profile photoJorrit Jongma's profile photoArtem Russakovskii's profile photo
Yeah, but I am using SuperSU. Unless +Chainfire made a new one recently...

Also, I can clearly modify /system, since I can rename files.
Huh. I just tried myself, since I know I copied the Cerberus apk into /system/app earlier today. It turns out that I can't copy from the internal storage, but I can copy from somewhere else, like /data. That's how I was able to grab the Cerberus apk and put it into /system.
+Jonathan Lam But how do you get it to /data? I couldn't copy into /data/local either. I ended up using TWRP's file manager in recovery to copy. 
+Artem Russakovskii I have no idea what you're doing. "adb remount" doesn't work on the stock adbd on a stock firmware, but works fine for me with adbd insecure. But even then, remounts of /system are not necessarily global and visible to all processes. If pushing to /data/local doesn't work, try pushing to /data/local/tmp . On some devices only one of those works. That all has absolutely nothing to do with SuperSU though, but with how 4.3 works. 

As for system app mover, no idea why that doesn't work. From what I've seen, it actually succeeds in remounting /system r/w, but it fails to detect that. I haven't looked in-depth though, so I may be wrong, but possibly the su shell has system remounted, but the Java process has not (which will now be common), and the code that checks r/w-ness is in the Java code. I'm just thinking out loud here, again, I have not investigated it.

As for that other post linked here as well as in the AndroidPolice articles, the good stuff is missing / misunderstood. If the problem was just the nosuid mount ... 

I might comment on all this further tomorrow, but I'm preparing to go on vacation, have a shitload of stuff to do, the timing on this couldn't possibly be any worse, etc.
+Jorrit Jongma I was basically describing my experience trying to copy files to /system the way I was used to, which wasn't working anymore. Remounts was showing an error, renaming worked, copying didn't. Since su is needed to remount and possibly copy to the system partition (not sure on the latter if /system is already r/w), I was under the impression that it's something in 4.3 or su that wasn't working right anymore. I'd still like to figure this one out. Copying in recovery when trying to test little changes to it is not ideal.

As for +Cody Toombs's post, he'll gladly take your input whenever you have it.
Well, you shouldn't need to. That's why I am asking what you're doing exactly. Because adb pushing to /data/local/tmp, then adb shell, then su, then remounting system with the mount command, then copying it from /data/local/tmp to /system, shouldn't be an issue.

Aside from doing that all manually, I've also just tested this with Root Explorer and that seems to work fine.

If you're getting the # prompt immediately when you type adb shell (and aren't using adbd insecure), you're using an insecure kernel - and that will not work properly. Long story, hopefully I can explain it later.

As for +Cody Toombs , don't misunderstand me as having a beef with him - it's just the situation. If I have the time I'll write an extensive post covering some of this later.
+Jorrit Jongma I usually use Total Commander for Android, then just copy from one pane to the other (/sdcard/ -> /data/local/ or /system/media/, for example). This used to work, but now doesn't. Astro and Solid Explorer don't either (I think at least SE should be root-friendly). I'm using a stock kernel, not an insecure one. I haven't tried Root Explorer, but from your instructions, it looks like straight file copying like that won't work anymore.
Haven't tried Astro but I have just tried Total Commander and Solid Explorer, neither of those seem aimed at this sort of "root" usage. I'm not so much surprised that they don't work now, as that I'm surprised they ever worked in any useful way before. If you want to do things you full permissions for, use an explorer built to work with root, like Root Explorer or ES File Manager.
+Jorrit Jongma Well, I never had problems with TC, because upon trying to write to ro partitions, it automatically asked to mount rw, and it's worked in the past on all my devices. I'll try RE.
Root Explorer works. Looks like it mounts /system rw correctly, while TC doesn't. I'll report this to the TC dev.
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