「Solved」爲何 android 虛擬終端與 adb shell 看到的是兩個不同的世界？？？！！！

[dukelec]

上面是 adb shell 看到的結果，下面 ooo.txt 是虛擬終端打 mount > ooo.txt 得到的。。。
/system 這個 adb 看是 ro, 虛擬終端裏面看是 rw, 因爲我是在虛擬終端裏面將 /system 重新挂載爲可寫，否則 mount > ooo.txt 無權限。
/mnt/gentoo 這個我是在虛擬終端裏面挂載的，可以 ls, cat 出裏面的文件內容，但文件管理器 ES File Explorer 看不到 /mnt/gentoo 下的文件，且 adb shell 也看不到。。。

代码： 全选

root@android:/system/duke # mount                                              
rootfs / rootfs ro,relatime 0 0
tmpfs /dev tmpfs rw,seclabel,nosuid,relatime,mode=755 0 0
devpts /dev/pts devpts rw,seclabel,relatime,mode=600 0 0
proc /proc proc rw,relatime 0 0
sysfs /sys sysfs rw,seclabel,relatime 0 0
selinuxfs /sys/fs/selinux selinuxfs rw,relatime 0 0
debugfs /sys/kernel/debug debugfs rw,relatime 0 0
none /acct cgroup rw,relatime,cpuacct 0 0
tmpfs /mnt/secure tmpfs rw,seclabel,relatime,mode=700 0 0
tmpfs /mnt/asec tmpfs rw,seclabel,relatime,mode=755,gid=1000 0 0
tmpfs /mnt/obb tmpfs rw,seclabel,relatime,mode=755,gid=1000 0 0
none /dev/cpuctl cgroup rw,relatime,cpu 0 0
/dev/block/mmcblk0p20 /persdata/absolute ext4 rw,seclabel,nosuid,nodev,relatime,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/system /system ext4 ro,seclabel,relatime,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/userdata /data ext4 rw,seclabel,nosuid,nodev,noatime,discard,journal_checksum,journal_async_commit,noauto_da_alloc,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/cache /cache ext4 rw,seclabel,nosuid,nodev,noatime,discard,journal_checksum,journal_async_commit,noauto_da_alloc,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/persist /persist ext4 rw,seclabel,nosuid,nodev,noatime,discard,journal_checksum,journal_async_commit,noauto_da_alloc,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/efs /efs ext4 rw,seclabel,nosuid,nodev,noatime,discard,journal_checksum,journal_async_commit,noauto_da_alloc,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/modem /firmware vfat ro,context=u:object_r:firmware:s0,relatime,gid=1000,fmask=0006,dmask=0006,allow_utime=0020,codepage=cp437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro 0 0
/data/container /mnt/shell/container sdcardfs rw,nosuid,nodev,relatime,uid=1000,gid=1000 0 0
/data/media /mnt/shell/emulated sdcardfs rw,nosuid,nodev,relatime,uid=1023,gid=1023 0 0
/dev/block/vold/179:33 /storage/extSdCard vfat rw,dirsync,nosuid,nodev,noexec,noatime,nodiratime,uid=1000,gid=1023,fmask=0002,dmask=0002,allow_utime=0020,codepage=cp437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro 0 0
/dev/block/vold/179:33 /mnt/secure/asec vfat rw,dirsync,nosuid,nodev,noexec,noatime,nodiratime,uid=1000,gid=1023,fmask=0002,dmask=0002,allow_utime=0020,codepage=cp437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro 0 0
tmpfs /storage/extSdCard/.android_secure tmpfs ro,seclabel,relatime,size=0k,mode=000 0 0
/dev/block/dm-0 /mnt/asec/com.kongedhk.DualLufsig-1 ext4 ro,dirsync,seclabel,nosuid,nodev,noatime 0 0
root@android:/system/duke # 
root@android:/system/duke # 
root@android:/system/duke # cat ooo.txt                                        
rootfs / rootfs ro,relatime 0 0
tmpfs /dev tmpfs rw,seclabel,nosuid,relatime,mode=755 0 0
devpts /dev/pts devpts rw,seclabel,relatime,mode=600 0 0
none /dev/cpuctl cgroup rw,relatime,cpu 0 0
proc /proc proc rw,relatime 0 0
sysfs /sys sysfs rw,seclabel,relatime 0 0
selinuxfs /sys/fs/selinux selinuxfs rw,relatime 0 0
debugfs /sys/kernel/debug debugfs rw,relatime 0 0
none /acct cgroup rw,relatime,cpuacct 0 0
tmpfs /mnt/secure tmpfs rw,seclabel,relatime,mode=700 0 0
tmpfs /mnt/asec tmpfs rw,seclabel,relatime,mode=755,gid=1000 0 0
/dev/block/dm-0 /mnt/asec/com.kongedhk.DualLufsig-1 ext4 ro,dirsync,seclabel,nosuid,nodev,noatime 0 0
tmpfs /mnt/obb tmpfs rw,seclabel,relatime,mode=755,gid=1000 0 0
/dev/block/mmcblk0p20 /persdata/absolute ext4 rw,seclabel,nosuid,nodev,relatime,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/system /system ext4 rw,seclabel,relatime,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/userdata /data ext4 rw,seclabel,nosuid,nodev,noatime,discard,journal_checksum,journal_async_commit,noauto_da_alloc,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/cache /cache ext4 rw,seclabel,nosuid,nodev,noatime,discard,journal_checksum,journal_async_commit,noauto_da_alloc,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/persist /persist ext4 rw,seclabel,nosuid,nodev,noatime,discard,journal_checksum,journal_async_commit,noauto_da_alloc,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/efs /efs ext4 rw,seclabel,nosuid,nodev,noatime,discard,journal_checksum,journal_async_commit,noauto_da_alloc,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/modem /firmware vfat ro,context=u:object_r:firmware:s0,relatime,gid=1000,fmask=0006,dmask=0006,allow_utime=0020,codepage=cp437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro 0 0
/data/container /mnt/shell/container sdcardfs rw,nosuid,nodev,relatime,uid=1000,gid=1000 0 0
/data/media /mnt/shell/emulated sdcardfs rw,nosuid,nodev,relatime,uid=1023,gid=1023 0 0
tmpfs /storage/emulated tmpfs rw,seclabel,nosuid,nodev,relatime,mode=050,gid=1028 0 0
/dev/block/vold/179:33 /storage/extSdCard vfat rw,dirsync,nosuid,nodev,noexec,noatime,nodiratime,uid=1000,gid=1023,fmask=0002,dmask=0002,allow_utime=0020,codepage=cp437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro 0 0
tmpfs /storage/extSdCard/.android_secure tmpfs ro,seclabel,relatime,size=0k,mode=000 0 0
/data/media /storage/emulated/0 sdcardfs rw,nosuid,nodev,relatime,uid=1023,gid=1023 0 0
/data/media /storage/emulated/0/Android/obb sdcardfs rw,nosuid,nodev,relatime,uid=1023,gid=1023 0 0
/data/media /storage/emulated/legacy sdcardfs rw,nosuid,nodev,relatime,uid=1023,gid=1023 0 0
/data/media /storage/emulated/legacy/Android/obb sdcardfs rw,nosuid,nodev,relatime,uid=1023,gid=1023 0 0
/dev/block/mmcblk1p2 /mnt/gentoo ext4 rw,seclabel,relatime,data=ordered 0 0
root@android:/system/duke # 

求解答。。。

[poloshiao]

爲何 android 虛擬終端與 adb shell 看到的是兩個不同的世界？

參閱 Introduction of Android Debug Bridge (ADB) 的功能
1. http://blog.yam.com/hansonlin211/article/19746129
2. http://developer.android.com/tools/help/adb.html
3. http://wiki.sdx-developers.com/android- ... ridge-adb/

[eexpress]

帖子重点不突出，看晕的。

[photor]

[dukelec]

Zygote: Restrict slave mountspace so Dalvik apps can mount system-wide volumes

Android 4.2 implements multi-user storage using per-process mount namespaces. Originally, everything under "/" (the entire filesystem hierarchy) is marked as a recursive-slave mountspace for all zygote instances. This is done so that user-storage sandbox mounts under /storage/emulated are hidden from other apps and users.

Unfortunately this means that any Dalvik app (actually, any program whose clone/fork ancestry includes a Dalvik zygote, which is everything except services spawned directly from init) cannot mount system-wide volumes. Thus, apps like CifsManager are effectively broken in Android 4.2, since its cifs mounts are only visible to the CifsManager app itself. All other apps see empty mountpoints instead of the mounted volume. Furthermore, Linux provides no provision for a process to "escape" a recursive-slave mountspace in versions prior to Linux 3.8 (setns syscall).

好吧，看來是時候研究一下 Linux Namespaces 了 。。。

[acrsgdw]

结果的确不同
挺奇怪的
mark一下