How can I mount an ext4 file system on OS X?

Question

Is there a safe, stable application for reading from and writing to ext4 file systems on Mac OS X?

If not, what's the best way to access the contents of an ext4 file system on Mac OS X?

Answer 1

The answer depends on you willingness to invest in commercial software:

If you don’t mind spending some money on a commercial product, Paragon’s ExtFS driver will give you read and write access to ext2 / ext3 / ext4 file systems. Version 10 supports all versions of OS X / macOS from 10.8 to 10.12.

If you are looking for a free solution, you can setup a Linux virtual machine, mount your volume(s) there and share it / them via Samba or (S)FTP. This post has some details on how to achieve this using VirtualBox, a free virtual machine application. Note this is not exactly a lightweight solution, even if using a prebuilt VirtualBox VM will spare you installing and configuring a Linux distro from scratch.

Answer 2

Building on Ken's answer: I used fuse4x and fuse-ext2 successfully, and I recommend fuse-ext2 over ext4fuse.

ext4fuse was a hassle for me, because it requires manual compilation and has no support for fuse4x options that would allow me to set access control. fuse-ext2 provides downloadable packages, and the 0.0.7 version worked just fine. I copied a few large ISOs over without any problem.

Answer 3

One can also install OSXFUSE completely via the brew command line package manager:

brew install homebrew/fuse/ext4fuse

Note that the installation tells certain commands need to be run as 'sudo' in addition to this.

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With Yosemite better have a look at this. And then make sure the directory is readable by your user by doing this. For it to work I had to use the wheel group like this:

sudo dscl . append /Groups/wheel GroupMembership $(whoami)

Answer 4

With recent changes to homebrew, this should be as simple as:

brew cask install osxfuse brew install ext4fuse

You may have to reboot.

ext4fuse is read-only, unfortunately. And you may need to use a flag to get it to work as a normal user.

Others viewing this question may be interested in libguestfs. I'm not aware of an OS X port, but considering that VirtualBox has an API, it's not out of the question.

I wonder why no one has written a compatibility layer to allow Linux kernel filesystem code to run in userspace/fuse. Or has someone?

Answer 5

Just for the record, I have tested Paragon ExtFS driver (trial version) on my MacBook Pro to write to ext4 partition in Linux. I found that the driver was very unstable, and it created corruptions to the filesystem that fsck was not able to repair neither in Linux nor in Disk Utility.

My idea was to have access to my /home partition from Mac OS X using this Paragon driver, but I don't suggest to do this setup. So far, I have my /home partition in Linux formatted to hfsplus with no journaling, and then I can access my files from Mac OS X. Of course, from time to time I get some problems in my FS but is not very frequent. However, I don't suggest this setup either (at least that you have an up to date backup for your daily work).

Finally, I believe that Paragon is more suitable maybe to use for external hard disks but anyways it is not very reliable for being software which license is expensive.

Update: As of May 2015, I have formatted my /home to ext4, and I mount the filesystem using fuse-ext2 in combination with FUSE for OS X. I can access the ext4 partition to read and write. It is more solid setup than the one I previously described above.

Answer 6

I had an ext4 formatted USB drive that I was able to mount after I installed osxfuse. Reading from it works great, but I am not sure if writing is safe.

Also, for moving files from OS X's filesystem (HFS+) to ext4, you may first want to remove those hidden .DS_Store files the OS X filesystem sneaks in as they occasionally cause bad inodes.

find /my/data/to/move -name '*.DS_Store' -type f -delete

It is better than having to fix them after with an fsck command.

Answer 7

If you're wondering what the command line is to mount an ext4 partition using fuse and ext2fuse (e.g. when installed using MacPorts port install ext2fuse) - then firstly you need to work out where the Linux partition is:

diskutil list

This will list all partitions for all disks and amongst them you should see the relevant ones listed under the TYPE column as Linux. Combine the diskX and partition number Y like this /dev/diskXsY - e.g:

mount -t fuse-ext2 /dev/disk1s2 ~/my_mount_point

It may complain about not being able to write to the log file but it should still mount the partition into your home mount point. But if you want to mount the partition into a system directory then you need to run it as root e.g:

sudo mount -t fuse-ext2 /dev/disk1s2 /sys_mount_point

If that doesn't work try:

sudo ext2fuse /dev/disk1s2 /sys_mount_point

Update: More recently I've found that fuse-ext2 has problems with certain newer ext4 features, so instead it is better to use ext4fuse (port install ext4fuse). Use the ext4fuse command directly:

sudo ext4fuse /dev/disk1s2 /sys_mount_point

It should be noted that you can only access the mounted filesystem as root/sudo. e.g.

sudo ls /sys_mount_point

Answer 8

You can boot Linux VM quickly on your OS X using Vagrant. You require to install VM provider such as VirtualBox and Vagrant either via .dmg file from the site or using brew cask.

Once you have vagrant command installed, run this in any selected folder:

vagrant init ubuntu/trusty64; vagrant up --provider virtualbox

^{This will generate Vagrantfile config file and .vagrant folder.}

and you'll have Linux box booted within few minutes (downloaded from Atlas Hashicorp repository).

Then connect to the box via command: vagrant ssh and try to mount your device inside Linux.

By default your current folder will be synched with /vagrant folder in VM. For more advanced options, you can modify Vagrantfile with required configuration.

So if you mount your filesystem within /vagrant folder, it will be automatically synched back to your macOS.

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Alternatively you just need to install a VirtualBox, run the GUI app, install and boot a minimal version of Linux e.g. Ubuntu in order to achieve the same as explained above.

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Above non-native solution are not ideal, but at least your macOS would be more stable rather than installing unstable kernel extensions which may cause a lot of system crashes.

Answer 9

There is also e2fsprogs available in MacPorts. I haven't tested it yet myself but looks promising.

Answer 10

Updated answer for (High) Sierra

For Sierra and High Sierra ext4fuse seems to work well for read access only and therefore it could probably be considered the preferred option. While other answers already give some usage examples I'll repeat it once again with some important details:

Install ext4fuse with:

brew install ext4fuse

You can mount as a normal user but in that case you'll only be able access world-readable files, that's why for full access you need to use sudo, e.g.:

sudo ext4fuse -o allow_other /dev/disk2s1

Here is a bash script which partially automates the process. When launched it will automatically create the mount point after you'll be prompted to enter one of the displayed device identifiers such as disk2s1:

diskutil list
read -p "Please type the EXT4 device identifier: " disk_id
MOUNT_POINT=~/mnt/$disk_id
mkdir -p ${MOUNT_POINT}
sudo ext4fuse -o allow_other /dev/$disk_id ${MOUNT_POINT}
echo "***TO UNMOUNT USE***: 'diskutil umount ${MOUNT_POINT}'"
open ${MOUNT_POINT}

To unmount you can use e.g. diskutil umount /dev/disk2s1 — if you get a message that unmounting failed then you can force unmounting with diskutil umount force /dev/disk2s1, although it would be cleaner to close the apps that are using files on the disk and retry unmounting in without force.

If you happen to have files owned by _lpoperator (apparently they are created when you use rsync with preserve group option), then the following command will allow you to access those files:

/usr/sbin/dseditgroup -o edit -a everyone -t group _lpoperator

Original answer for Yosemite and older (deprecated)

Two packages are needed in order to enable EXT2/3/4 support on OSX: OSXFUSE and FUSE-EXT2.

The homebrew formulas for OSXFUSE and FUSE-EXT2 did not work for me on either mavericks or yosemite.

What did work was the following:

1. Manually download and install the OSXFUSE DMG from http://osxfuse.github.io/. IMPORTANT: Once you launch the PKG installer, make sure you selected MacFUSE Compatibility Layer in the wizard (it is not enabled by default) - without it I was getting an error while trying to mount.
2. Manually download FUSE-EXT2 from http://sourceforge.net/projects/fuse-ext2/ or for Sierra/El Capitan from https://github.com/gpz500/fuse-ext2/releases and run the PKG installer.

Once you have both OSXFUSE and FUSE-EXT2 installed you can mount the ext2/ext3/ext4 partitions as mentioned in other answers:

1. Find the device name for the EXT partition you want to mount (e.g. disk0s2 in the example below, (UPDATE) in later MacOS versions ext3/ext4 partitions might be labelled Microsoft Basic Data and not Linux):

   # diskutil list | grep Linux 1: Linux_Swap 8.2 GB disk0s1 2: Linux 119.9 GB disk0s2

2. Mount the partition to an existing mount point:

   sudo mkdir -p /Volumes/ext4 sudo mount -t fuse-ext2 /dev/disk0s2 /Volumes/ext4

Mounting as a regular user did not work for me. Probably this can be fixed by fiddling with permissions, but I didn't look into it.

Note: My suspicion is that the homebrew formulas did not work because homebrew installs osxfuse without the MacFUSE Compatibility Layer.

There are two osxfuse packages in homebrew:

# brew search osxfuse
>>> osxfuse
>>> Caskroom/cask/osxfuse

Both versions fail to mount EXT partitions. Most likely, the DMG version (Caskroom/cask/osxfuse) fails because homebrew installs the package with default settings, which means that MacFUSE Compatibility Layer is not included. The main osxfuse version probably needs some special installation parameter to enable MacFUSE compatibility, so until this is fixed in homebrew the manual DMG method should be used.

This method worked for me on mavericks, yosemite, elcapitan and sierra.

EXT2/3/4 mount script for older OSX versions (deprecated)

To save some extra typing I use a tiny script which takes the partition name such as disk0s2 and mounts it under /Volumes/disk0s2, creating the folder if necessary:

### mount_ext4.sh
sudo mkdir -p "/Volumes/$1"
sudo mount -t fuse-ext2 "/dev/$1" "/Volumes/$1"
open "/Volumes/$1"

The script is called with the partition name that you look up via diskutil list, e.g. mount_ext4.sh disk2s3.