[Q] No lost+found directory on /system partition - Android Q&A, Help & Troubleshooting

I recently got a phone with Gingerbread (2.3.5) and like the fact that it now uses ext4. However, I am a bit confused. There is no lost+found directory on the /system partition.
It caused some problems with being able to write to the partition when using a couple different versions of Linux (Fedora 16 and Ubuntu 11.10). /var/log/messages showed numerous errors pertaining to the partition and suggested I run fsck. Ran fsck, and it reported that lost+found was missing, and asked if I would like it created.
Not understanding why it was missing in the first place, I have not created it yet. Instead, I was able to use an older version of Linux (Ubuntu 10.04) and was able to gain rw access.
Does anybody know why lost+found might be missing on my phone, and/or is it missing on other Gingerbread phones?

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Partitions - how many, where are they, etc.

Partitions are something we usually don't need to mess with - probably shouldn't mess with. That said - to understand how things work, it would be nice to peek around and look. I have enough experience with linux to be dangerous but not enough to answer my question on the gtab. I know there are multiple partititons - clockwork mod can wipe some. I see when I do nvflash that a bunch of partitions are restored. When we repartition with clockwork we set the size of only one partition to 2040 and the swap partition to 0 - what about all the others? Now, if I use terminal emulator or can get up to what I think is the root directory. In linux I could use fdisk -l and it would show me the various partitions. It doesn't produce any output here. I'm sure I just don't understand the structure so I'm not phrasing the command properly. There is also probably another place that would clue me in as to what partitions are mounted where but I don't know it. Anyone have any ideas for me?

Temp directories in an Android file system

Hi,
Are there any temp, volatile directories in the Android file system that get wiped once the device is off? In Linux we have /tmp, but this doesn't seem to exist in Android.
Thanks.
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Whether /tmp is cleared on boot differ between different distributions, RHEL does for example not.
The easiest way to identify which ram disks you have available is most likely to run mount through an ADB shell and see what you get of the type tmpfs.
How to I see what I get of the type tmpfs?

[Q] Change /data to ext4

Hi everyone,
I am eager to try out ICS' disk encryption feature. One thing is it requires that /data is in ext4 format. This is on a SonyEricsson Active and the default FS type for /data is yaffs2.
I've tried a few different things but I'm not getting anywhere. I've also seen a few threads here with posts of zip files that should do it but none for the SE Active. I would like to try this from the Recovery mod CLI. I already have ICS 9.2 installed and running on it no problem.
Any suggestions?
Thanks! I hope this is the right forum to post this in.

[Q] Mounting ext2 partition

I've created a single primary Ext2 partition in my phone's external SD card but Android refuses to mount it automatically. Whenever I attempted to mount it manually it kept throwing the error "mount operation not supported on transport endpoint".
How can I mount it?
Using (SlimKat) Android 4.4.2.
EDIT: I'm now able to mount it only manually but have to specify ext4 as its filesystem -- why and will it make a difference since ext2 is non-journalled? Also, I tried adding a mount entry in /fstab.smdk4x12 but it was deleted upon reboot; does this mean no manual entries are allowed in that file and I will instead have to hack my own /init-xx.rc file to manually mount the partition at boot time?
miguelg_ said:
I've created a single primary Ext2 partition in my phone's external SD card but Android refuses to mount it automatically. Whenever I attempted to mount it manually it kept throwing the error "mount operation not supported on transport endpoint".
How can I mount it?
Using (SlimKat) Android 4.4.2.
EDIT: I'm now able to mount it only manually but have to specify ext4 as its filesystem -- why and will it make a difference since ext2 is non-journalled? Also, I tried adding a mount entry in /fstab.smdk4x12 but it was deleted upon reboot; does this mean no manual entries are allowed in that file and I will instead have to hack my own /init-xx.rc file to manually mount the partition at boot time?
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Why not just reformat to ext4?
es0tericcha0s said:
Why not just reformat to ext4?
Click to expand...
Click to collapse
Ultimately that's what I'll need to do but was hoping to use the non-journalled ext2. Is it not supported by Android or it the case that only some versions support it (in which case, what idiocy!)?
Have to say I'm beginning to truly hate Android. They might as well build their own kernel such that Linux (and by implication UNIX) is removed from the mix for they have completely butchered this OS. I suppose this is what happens when egos larger than the world are responsible for designing software; NIH syndrome.
Answering myself: if anyone is wondering how to automount a partition at boot time, you'll have to create your own init script and place in /system/etc/init.d/.
Well, realistically, the amount of people that have any use for mounting ext2/3/4 etc partitions is a very small % of users. Most people with android phones don't even know what Linux is, much less know about different kinds of partitions and what they are used for - or have a need for it. 99% of things you would NEED to do on a phone would be covered by the fat32 and exFat types. Of course, here on XDA, you'll find plenty of posts, guides, complaints about it, etc but there's obviously a certain type of user that seeks out or finds XDA and are more inclined to know of or have use for more technical things like this.
As far as auto-mounting the script on boot, you have to be rooted with init.d enabled and not all phones have full /system RW capabilities to even add stuff like that even when rooted. This is rare, but there's some HTCs and others like that. Often times there are ways around, but just saying, it's not a universal thing.
es0tericcha0s said:
Well, realistically, the amount of people that have any use for mounting ext2/3/4 etc partitions is a very small % of users. Most people with android phones don't even know what Linux is, much less know about different kinds of partitions and what they are used for - or have a need for it. 99% of things you would NEED to do on a phone would be covered by the fat32 and exFat types. Of course, here on XDA, you'll find plenty of posts, guides, complaints about it, etc but there's obviously a certain type of user that seeks out or finds XDA and are more inclined to know of or have use for more technical things like this.
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That doesn't excuse the fact that they've deliberately crippled the OS. As an example, the FAT filesystems don't support symbolic links, which means that if you want to move any data outside of internal storage for whatever reason, you pretty much need an extX partition. Besides, those people (the vast majority) who don't know and don't care about the internals of their devices aren't the ones creating software for said devices in the first place. We are. And so these technical aspects matter and are relevant to us, not the masses.
es0tericcha0s said:
As far as auto-mounting the script on boot, you have to be rooted with init.d enabled and not all phones have full /system RW capabilities to even add stuff like that even when rooted. This is rare, but there's some HTCs and others like that. Often times there are ways around, but just saying, it's not a universal thing.
Click to expand...
Click to collapse
Didn't know about that limitation. Can you not remount the rootfs with RW privileges? And do you mean to say that some devices don't even support init.d; if so, what mechanism do they have in place?
miguelg_ said:
That doesn't excuse the fact that they've deliberately crippled the OS. As an example, the FAT filesystems don't support symbolic links, which means that if you want to move any data outside of internal storage for whatever reason, you pretty much need an extX partition. Besides, those people (the vast majority) who don't know and don't care about the internals of their devices aren't the ones creating software for said devices in the first place. We are. And so these technical aspects matter and are relevant to us, not the masses.
Didn't know about that limitation. Can you not remount the rootfs with RW privileges? And do you mean to say that some devices don't even support init.d; if so, what mechanism do they have in place?
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Well, cripple might be a bit of hyperbole considering it's not something most people would need. I get your point though, it is weird that it's not native since it works with Linux generally. You can link symbolically to FAT systems while rooted with something like this:
https://play.google.com/store/apps/details?id=com.devasque.fmount
And yes, the tech people are creating software for these devices, but they are made for the general public, because that's who buy 90% of these things.
Could you please clarify what you said earlier on the read-only init.d and even some devices not supporting it? Again, thanks for your input, es0tericcha0s.
miguelg_ said:
Could you please clarify what you said earlier on the read-only init.d and even some devices not supporting it? Again, thanks for your input, es0tericcha0s.
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Sure. Most android devices, actually I can't think of any of the top of my head, don't come with native init.d support or even have init.d that is not accessible. It's just not there. It's enabled in almost all custom roms, or you can add it yourself to many stock roms via a couple different ways like this:
https://play.google.com/store/apps/details?id=com.androguide.universal.init.d
As far as the system RW issue, some phones, like many newer HTCs, have the system protected so that you can make changes to the /system while booted, no problem, but once you reboot, all the changes will get undone. Very annoying. Example:
https://www.youtube.com/watch?v=KV3YaMBnEYI

irulu 10.1 root/remount problems solved

I own an irulu K1001L1 10.1 (build number A20_K1001_K1001L1.20130713), a cheap one.
Many people complain about "partial rooting" and being unable to remount system in rw mode. Clueless as I was, I had tried several times with Uberizer, z4root and SRSroot, to no avail (the problem is not in the root, in my tablet su came by default in xbin directory).
D_rex (http://forum.xda-developers.com/show...2606510&page=2) found an effective solution which also helped in my situation: I think my tablet came with "su" application by default (notice overclocking worked) but due to /dev/block/nandd ext4 partition (I think /system starts at some offset) containing some errors (seen in dmesg) and due to this partition having the "s_errors" flag (behavior when errors detected) set to "mount read-only (02)", the partition is ALWAYS mounted read only, and remount as root doesn't change anything. More info on this ext4 option can be found here: https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout.
For me, the solution that worked was changing that flag s_errors to continue (01). I wasn't able to run e2fsck as the partition is already mounted; and I wasn't able to do a fsck in recovery mode since the recovery mode of this tablet lacks seems to lack both shell and e2fsck.
Tune2fs (old version precompiled here can change that flag in the partition. Using adb shell I pushed it to de device, set attribute as executable and run it, successfuly changing that "behavior when errors detected" in both partitions.
It has been suggested filesystem errors are linked to stability and realiability problems. Unfortunately this tablet lacks a version of CWM o TWRP as a recovery custom rom. I also adjusted the "max-mount-counts" value via tune2fs -c hoping it forces Android to run e2fsck, but it seems dmesg keeps displaying errors. I can only hope this problem is given more attention by developers.
After this I used the usual tools to root the device, noticing I had spent many hours in this cheap tablet. I should also mention by default now my tablet mounts in read-only mode (which is of course safer) but lets me change to rw whenever I want.
I have not been able to fix the ext4 errors. As others have explained, ls -al /dev/block can be used to better understand the images structure. System partition (nandd) contains the file e2fsck , but that file seems to be unavailable before mounting. Editing init.rc and associated files didn't force a diskcheck; I have not tried imaging the recovery partition (/dev/block/nandg) with dd and manually adding the required tools.I should also mention by default now my tablet mounts in read-only mode (which is of course safer) but lets me change to rw whenever I want.
On a side note, the adb driver setup tool found here didnt work for me (it seems &USER_PROFILE% in the .bat file should be replaced by "%USER_PROFILE%" and Desktop should be replaced according to the language of your operating system. Nevertheless the tool didn't work for me and I had to install another driver found in Uberizer distribution as the official "android_winusb.inf" didn't work in my Windows XP computer.
Thanks to the creators of tune2fs, to D_rex and other people/programs mentioned here. This is my experience with this problem; I'm not responsible if anyone tries this and bricks his device. All brands are property of their owners.
Good luck and Good bye

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