jmtpfs:

jmtpfs is a FUSE and libmtp based filesystem for accessing MTP (Media Transfer Protocol) devices. It was specifically designed for exchaning files between Linux (and Mac OS X) systems and newer Android devices that support MTP but not USB Mass Storage.

The goal is to create a well behaved filesystem, allowing tools like find and rsync to work as expected. MTP file types are set automatically based on file type detection using libmagic. Setting the file appears to be necessary for some Android apps, like Gallery, to be able to find and use the files.

Since it is meant as an Android file transfer utility, and I don't have any non-Android MTP devices to test with, playlists and other non-file based data are not supported.

Building and installing:

See the INSTALL file.

Usage:

Run jmtpfs with a directory as a parameter, and it will mount to that directory the first MTP device it finds. You can then access the files on the device as if it were a normal disk.

[jason@colossus ~]$ jmtpfs ~/mtp Device 0 (VID=04e8 and PID=6860) is a Samsung GT-P7310/P7510/N7000/I9100/Galaxy Tab 7.7/10.1/S2/Nexus/Note. Android device detected, assigning default bug flags [jason@colossus ~]$ ls ~/mtp Internal Storage [jason@colossus ~]$ ls ~/mtp/InternalStorage/ Android burstlyImageCache DCIM Music Notifications Pictures testdir [jason@colossus ~]$ df -h ~/mtp/InternalStorage Filesystem Size Used Avail Use% Mounted on jmtpfs 14G 3.1G 11G 23% /home/jason/mtp [jason@colossus ~]$ cd ~/mtp/InternalStorage/ [jason@colossus Internal Storage]$ ls Android burstlyImageCache DCIM Music Notifications Pictures testdir [jason@colossus Internal Storage]$ cat > test.txt Hello Android! [jason@colossus Internal Storage]$ ls Android DCIM Notifications testdir burstlyImageCache Music Pictures test.txt [jason@colossus Internal Storage]$ cat test.txt Hello Android! [jason@colossus Internal Storage]$ rm test.txt [jason@colossus Internal Storage]$

Pass the -l option will list the attached MTP devices.

[jason@colossus ~]$ workspace/jmtpfs/src/jmtpfs -l Device 0 (VID=04e8 and PID=6860) is a Samsung GT-P7310/P7510/N7000/I9100/Galaxy Tab 7.7/10.1/S2/Nexus/Note. Available devices (busLocation, devNum, productId, vendorId, product, vendor): 2, 19, 0x6860, 0x04e8, GT-P7310/P7510/N7000/I9100/Galaxy Tab 7.7/10.1/S2/Nexus/Note, Samsung

You can choose which device to mount with the -device option.

[jason@colossus ~]$ workspace/jmtpfs/src/jmtpfs -device=2,19 ~/mtp Device 0 (VID=04e8 and PID=6860) is a Samsung GT-P7310/P7510/N7000/I9100/Galaxy Tab 7.7/10.1/S2/Nexus/Note. Android device detected, assigning default bug flags [jason@colossus ~]$ ls ~/mtp Internal Storage

Unmount with fusermount.

[jason@colossus ~]$ ls ~/mtp Internal Storage [jason@colossus ~]$ fusermount -u ~/mtp [jason@colossus ~]$ ls ~/mtp [jason@colossus ~]$

Performance and implementation notes:

libmtp (and I assume the MTP protocol itself) doesn't support seeking within a file or partial file reads or writes. You have to fetch or send the entire file. To simluate normal random access files, when a file is opened the entire file contents are copied from the device to a temporary file. Reads and writes then operate on the temporary file. When the file is closed (or if a flush or fsync occurs) then if a write has occurred since the file was last opened the entire contents of the temporary file are sent back to the device. This means repeatedly opening a file, making a small change, and closing it again will be very slow.

Renaming or moving a file is implemented by copying the file from the device, writing it back to the device under the new name, and then deleting the original file. This makes renames, especially for large files, slow. This has special significance when using rsync to copy files to the device. Rsync copies to a temporary file, and then when the copy is complete it renames the temporary file to the real filename. So when rsyncing to a jmtpfs filessystem, for each file, the data gets copied to the device, read back, and then copied to the device again. There is a true rename (but not move) supported by libmtp, but this appears to confuse some Android apps, so I don't use it. Image files, for example, will disappear from the Gallery if they're renamed.