mmount

mmount [options] <image_file> <mount_point>

--memfd
    Use memfd_create() backend.

--tmpfs
    Use tmpfs backend.

--ramfs
    Use ramfs backend.

-o <options>
    Pass options to the FUSE mount. Refer to mount.fuse(8) for possible options.

<image_file>
    The disk image file to mount.

<mount_point>
    The directory where the filesystem will be mounted.

The mmount command provides a user-space interface for mounting memory-backed filesystems. Unlike the standard mount command, mmount does not require root privileges, making it useful for testing filesystems, accessing disk images, or creating temporary writable storage. It leverages the FUSE (Filesystem in Userspace) infrastructure to allow regular users to implement and mount their own filesystem drivers without needing kernel modifications. It supports multiple memory backend options (memfd, tmpfs, ramfs) so user can choose which one to use based on their particular needs. The filesystem data resides entirely in RAM, improving performance for read/write operations, however the mount points disappear when the user logs off or the system shuts down.

Data stored in memory-backed filesystems is volatile and will be lost upon unmounting, system reboot, or user log out. Ensure all data is backed up to a persistent storage medium if it needs to be preserved.

Choosing the right backend option (memfd, tmpfs, ramfs) is crucial. memfd offers better isolation, tmpfs can swap data to disk if memory is scarce, and ramfs offers no swapping which guarantees performance but can cause out of memory errors. The user must analyze their needs before selecting a backend to use with mmount.

mmount is often part of a larger package of utilities related to FUSE. Its development is intertwined with the evolution of FUSE and its growing popularity for user-space filesystem implementations.

fusermount(1), mount(8), umount(8)