[Android Q&A, Help & Troubleshooting] rund3:
You mean, why I want it, right?

Because after my old phone broke, the only way I could backup files was to copy them from twrp.

Now I can't copy data back because I don't have access to data directory, because of missing root.

I've already written a 300 lines Perl script to convert SQLite-DB of old address book to cvf files, but it's the only application, where that kind of workaround can be applied.

But also to get rid of (partly periodically reinstalling) bloatware directly (without ADB).

And of course for next backup (without having to store stuff on google/samsung data centers)

There is a /system/build.prop, but I don't even have read access to it.

Also /system is not a separate partition, so it is also read-only.

/system:

1|xcoverpro:/system $ ls -l
ls: ./info.extra: Permission denied
total 9640
drwxr-xr-x 2 root root 4096 2008-12-31 16:00 apex
drwxr-xr-x 123 root root 4096 2008-12-31 16:00 app
drwxr-x--x 4 root shell 8192 2008-12-31 16:00 bin
-rw------- 1 root root 3371 2008-12-31 16:00 build.prop
drwxr-xr-x 3 root root 4096 2008-12-31 16:00 cameradata
drwxr-xr-x 3 root root 4096 2008-12-31 16:00 container
drwxr-xr-x 17 root root 4096 2008-12-31 16:00 etc
drwxr-xr-x 2 root root 12288 2008-12-31 16:00 fonts
drwxr-xr-x 5 root root 4096 2008-12-31 16:00 framework
drwxr-xr-x 3 root root 4096 2008-12-31 16:00 hidden
drwxr-xr-x 7 root root 24576 2008-12-31 16:00 lib
drwxr-xr-x 8 root root 28672 2008-12-31 16:00 lib64
-rw-r--r-- 1 root root 280 2008-12-31 16:00 lkm_sec_info
drwxr-xr-x 3 root root 4096 2008-12-31 16:00 media
drwxr-xr-x 189 root root 8192 2008-12-31 16:00 priv-app
lrw-r--r-- 1 root root 8 2008-12-31 16:00 product -> /product
-rw-r--r-- 1 root root 9711940 2008-12-31 16:00 recovery-from-boot.p
drwxr-xr-x 9 root root 4096 2008-12-31 16:00 saiv
drwxr-xr-x 2 root root 4096 2008-12-31 16:00 tee
-rw-r--r-- 1 root root 257 2008-12-31 16:00 tima_measurement_info
drwxr-xr-x 4 root root 4096 2008-12-31 16:00 tts
drwxr-xr-x 7 root root 4096 2008-12-31 16:00 usr
lrw-r--r-- 1 root root 7 2008-12-31 16:00 vendor -> /vendor
drwxr-xr-x 3 root root 4096 2008-12-31 16:00 voicebargeindata
drwxr-xr-x 2 root root 4096 2008-12-31 16:00 vramdiskddata

/proc/mount:

/dev/block/dm-4 / ext4 ro,seclabel,relatime,block_validity,discard,delalloc,barrier,user_xattr,acl,i_version 0 0
tmpfs /dev tmpfs rw,seclabel,nosuid,relatime,size=1812700k,nr_inodes=453175,mode=755 0 0
devpts /dev/pts devpts rw,seclabel,relatime,mode=600,ptmxmode=000 0 0
proc /proc proc rw,relatime,gid=3009,hidepid=2 0 0
sysfs /sys sysfs rw,seclabel,relatime 0 0
selinuxfs /sys/fs/selinux selinuxfs rw,relatime 0 0
tmpfs /mnt tmpfs rw,seclabel,nosuid,nodev,noexec,relatime,size=1812700k,nr_inodes=453175,mode=755,gid=1000 0 0
tmpfs /apex tmpfs rw,seclabel,nosuid,nodev,noexec,relatime,size=1812700k,nr_inodes=453175,mode=755 0 0
/dev/block/platform/13520000.ufs/by-name/metadata /metadata ext4 rw,seclabel,nosuid,nodev,noatime,journal_checksum,noauto_da_alloc,i_version 0 0
/dev/block/dm-5 /vendor ext4 ro,seclabel,relatime,block_validity,discard,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/dm-6 /product ext4 ro,seclabel,relatime,block_validity,discard,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/dm-7 /odm ext4 ro,seclabel,relatime,block_validity,discard,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/dm-8 /prism ext4 ro,seclabel,relatime,block_validity,discard,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/dm-9 /optics ext4 ro,seclabel,relatime,block_validity,discard,delalloc,barrier,user_xattr,acl,i_version 0 0
none /dev/cg2_bpf cgroup2 rw,nosuid,nodev,noexec,relatime 0 0
none /dev/cpuctl cgroup rw,nosuid,nodev,noexec,relatime,cpu 0 0
none /acct cgroup rw,nosuid,nodev,noexec,relatime,cpuacct 0 0
none /dev/cpuset cgroup rw,nosuid,nodev,noexec,relatime,cpuset,noprefix,release_agent=/sbin/cpuset_release_agent 0 0
none /dev/memcg cgroup rw,nosuid,nodev,noexec,relatime,memory 0 0
none /dev/stune cgroup rw,nosuid,nodev,noexec,relatime,schedtune 0 0
/sys/kernel/debug /sys/kernel/debug debugfs rw,seclabel,relatime 0 0
none /config configfs rw,nosuid,nodev,noexec,relatime 0 0
tmpfs /mnt/secure/asec tmpfs rw,seclabel,relatime,size=1812700k,nr_inodes=453175,mode=700 0 0
tmpfs /mnt/sde tmpfs rw,seclabel,relatime,size=1812700k,nr_inodes=453175,mode=700 0 0
bpf /sys/fs/bpf bpf rw,nosuid,nodev,noexec,relatime 0 0
pstore /sys/fs/pstore pstore rw,seclabel,nosuid,nodev,noexec,relatime 0 0
adb /dev/usb-ffs/adb functionfs rw,relatime 0 0
tracefs /sys/kernel/debug/tracing tracefs rw,seclabel,relatime 0 0
/dev/block/by-name/omr /omr ext4 rw,seclabel,nosuid,nodev,noatime,journal_checksum,noauto_da_alloc,i_version 0 0
/dev/block/platform/13520000.ufs/by-name/cache /cache ext4 rw,seclabel,nosuid,nodev,noatime,journal_checksum,noauto_da_alloc,i_version 0 0
/dev/block/platform/13520000.ufs/by-name/efs /mnt/vendor/efs ext4 rw,seclabel,nosuid,nodev,noatime,journal_checksum,noauto_da_alloc,i_version 0 0
/dev/block/platform/13520000.ufs/by-name/sec_efs /efs ext4 rw,seclabel,nosuid,nodev,noatime,journal_checksum,noauto_da_alloc,i_version 0 0
tmpfs /storage tmpfs rw,seclabel,nosuid,nodev,noexec,relatime,size=1812700k,nr_inodes=453175,mode=755,gid=1000 0 0
/dev/block/platform/13520000.ufs/by-name/userdata /data f2fs rw,lazytime,seclabel,nosuid,nodev,noatime,background_gc=on,discard,no_heap,user_xattr,inline_xattr,acl,inline_data,inline_dentry,extent_cache,mode=adaptive,active_logs=6,reserve_root=9477,reserve_core=1280,resuid=0,resgid=5678,usrquota,grpquota,alloc_mode=reuse,fsync_mode=nobarrier 0 0
/dev/block/loop2 /apex/com.android.media@292000301 ext4 ro,dirsync,seclabel,nodev,noatime,block_validity,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/loop2 /apex/com.android.media ext4 ro,dirsync,seclabel,nodev,noatime,block_validity,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/loop3 /apex/com.android.resolv@290000000 ext4 ro,dirsync,seclabel,nodev,noatime,block_validity,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/loop3 /apex/com.android.resolv ext4 ro,dirsync,seclabel,nodev,noatime,block_validity,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/loop4 /apex/com.android.tzdata@291900801 ext4 ro,dirsync,seclabel,nodev,noatime,block_validity,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/loop4 /apex/com.android.tzdata ext4 ro,dirsync,seclabel,nodev,noatime,block_validity,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/loop5 /apex/com.android.media.swcodec@292000501 ext4 ro,dirsync,seclabel,nodev,noatime,block_validity,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/loop5 /apex/com.android.media.swcodec ext4 ro,dirsync,seclabel,nodev,noatime,block_validity,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/loop6 /apex/com.android.apex.cts.shim@1 ext4 ro,dirsync,seclabel,nodev,noatime,block_validity,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/loop6 /apex/com.android.apex.cts.shim ext4 ro,dirsync,seclabel,nodev,noatime,block_validity,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/loop7 /apex/com.android.conscrypt@290000000 ext4 ro,dirsync,seclabel,nodev,noatime,block_validity,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/loop7 /apex/com.android.conscrypt ext4 ro,dirsync,seclabel,nodev,noatime,block_validity,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/loop8 /apex/com.android.runtime@1 ext4 ro,dirsync,seclabel,nodev,noatime,block_validity,delalloc,barrier,user_xattr,acl,i_version 0 0
/dev/block/loop8 /apex/com.android.runtime ext4 ro,dirsync,seclabel,nodev,noatime,block_validity,delalloc,barrier,user_xattr,acl,i_version 0 0
none /dev/freezer cgroup rw,relatime,freezer 0 0
/data/knox/secure_fs/enc_media /mnt/shell/enc_emulated sdcardfs rw,nosuid,nodev,noexec,noatime,fsuid=1000,fsgid=1000,gid=9997,multiuser,derive_gid,default_normal,reserved=20MB 0 0
/data/media /mnt/runtime/default/emulated sdcardfs rw,nosuid,nodev,noexec,noatime,fsuid=1023,fsgid=1023,gid=1015,multiuser,mask=6,derive_gid,default_normal,reserved=20MB 0 0
/data/media /storage/emulated sdcardfs rw,nosuid,nodev,noexec,noatime,fsuid=1023,fsgid=1023,gid=1015,multiuser,mask=6,derive_gid,default_normal,reserved=20MB 0 0
/data/media /mnt/runtime/read/emulated sdcardfs rw,nosuid,nodev,noexec,noatime,fsuid=1023,fsgid=1023,gid=9997,multiuser,mask=23,derive_gid,default_normal,reserved=20MB 0 0
/data/media /mnt/runtime/write/emulated sdcardfs rw,nosuid,nodev,noexec,noatime,fsuid=1023,fsgid=1023,gid=9997,multiuser,mask=7,derive_gid,default_normal,reserved=20MB 0 0
/data/media /mnt/runtime/full/emulated sdcardfs rw,nosuid,nodev,noexec,noatime,fsuid=1023,fsgid=1023,gid=9997,multiuser,mask=7,derive_gid,default_normal,reserved=20MB 0 0

bd?

All in one tool also doesn't work (at least the "Recovery Flasher and Device Rooter"-Button).

.NET-Error (.NET Framework 4.5 already installed):

System.ArgumentOutOfRangeException: InvalidArgument=Value mit dem Wert 3 ist für index ungültig.
Parametername: index
bei System.Windows.Forms.ListViewItem.ListViewSubItemCollection.get_Item(Int32 index)
bei TOOL_ALL_IN_ONE.Main.ReadDeviceInfo(Int32 membro)
bei TOOL_ALL_IN_ONE.Main.RecoveryFlasher_Click(Object sender, EventArgs e)
bei System.Windows.Forms.Control.OnClick(EventArgs e)
bei System.Windows.Forms.Button.OnClick(EventArgs e)
bei System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
bei System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
bei System.Windows.Forms.Control.WndProc(Message& m)
bei System.Windows.Forms.ButtonBase.WndProc(Message& m)
bei System.Windows.Forms.Button.WndProc(Message& m)
bei System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
bei System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
bei System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Edit: Button works on a different PC, but only offers to flash TWRP (or other recovery), which is not available for my device and most likely would also cause vbmeta error on boot.

OK, thanks, noted if I ever get access to that file.