eject — eject removable media

Overview

eject unmounts (if needed) and ejects removable media — CD/DVD/BD trays, tape cartridges, ZIP/floppy drives, and SCSI-attached devices — with one command. It accepts either a device node (/dev/sr0) or a mountpoint (/media/cdrom) and resolves the backing device itself, which is what makes it ergonomic: you almost never need to know which /dev/ name the drive got.

Debian bookworm ships it in its own eject package (built from the util-linux source tree, which absorbed the historical standalone eject by Jeff Tranter) at /usr/bin/eject, man section 1. Besides opening the tray it can close it (-t), toggle (-T), set auto-eject (-a), software-lock the door (-i), select changer slots (-c), and set/list CD-ROM speeds (-x/-X).

It is often confused with umount (which only unmounts — the tray stays shut and, for many devices, media stays powered) and with modern desktop tooling (udisksctl, file-manager buttons) that wraps the same ioctls with session policy on top.

Synopsis

eject [options] [device|mountpoint]

Common one-line forms:

eject /dev/sr0          # open the tray of the first optical drive
eject /media/cdrom      # resolve mountpoint → device → unmount → eject
eject -T /dev/sr0       # toggle: close if open, open if closed
eject -n /media/cdrom   # show what would be ejected, do nothing

How It Works

Resolution, unmount, then the ioctl

eject runs a three-step decision pipeline:

 argument ──► resolve to a device ──► unmount if mounted ──► eject ioctl
   /dev/sr0    (mountpoint lookup      (unless -m)          CDROMEJECT /
   /media/x    via mount table,        (and sibling         SG_IO / tape
               -d shows default)        partitions)          offload

1. Resolve. A mountpoint is mapped to its device by scanning the kernel mount table; a bare name like cdrom is tried against /dev. Newer versions also handle multi-partition devices: if any partition of the device is mounted, all of them are unmounted (skippable with -M).
2. Unmount. Unless -m is given, mounted filesystems on the device are unmounted first — ejecting a mounted medium is what older systems refused outright, and even today a busy mount blocks the eject.
3. Eject. The appropriate low-level operation is attempted per device type: the CD-ROM eject ioctl for optical drives, SCSI commands via the generic layer for -s devices, tape unload for -q, floppy eject for -f.

The -n dry run

-n (--noop) prints the resolved device and stops. In scripts this is the safe way to turn a user-supplied mountpoint into a device name without side effects:

$ eject -n /media/cdrom
eject: device is `/dev/sr0'

Beyond opening the tray

• -t closes the tray (only on drives that support software tray close).
• -T toggles — handy for single-button workflows on drives whose buttons are inaccessible (slot-loaders, Mac Minis, racked chassis).
• -a on sets auto-eject: the medium pops out automatically when unmounted.
• -i on engages the software eject lock — the drive refuses manual button ejects too. Useful against accidental yanking of mounted media.
• -c <slot> addresses multi-disc changers; -x <n> caps drive speed (quieter/less vibration when reading), -X lists supported speeds.

Options That Matter

Selection and probing

Media type

Drive control

Usage Patterns

# The everyday case: eject by mountpoint, no /dev name needed
eject /media/cdrom

# Script-safe resolution without side effects
dev=$(eject -n /media/cdrom 2>/dev/null); echo "$dev"

# Unmount and spin down a USB stick as a "safely remove" equivalent
eject /dev/sdb1

# Slot-loading drive with no button: toggle from the keyboard
eject -T /dev/sr0

# Prevent anyone pressing the physical button from yanking a mounted disc
sudo eject -i on /dev/sr0

# Pop the disc the moment it is unmounted (kiosk workflow)
sudo eject -a on /dev/sr0

# See every step while debugging a stubborn drive
eject -v /dev/sr0

# Cap the reading speed to quiet a noisy drive
sudo eject -x 8 /dev/sr0

# Changer: load disc 3
eject -c 3 /dev/sr0

# Unload a tape
eject -q /dev/st0

# What would happen, verbosely, on a multi-partition USB drive
eject -nv /media/user/USBDRIVE

Nuances and Gotchas

• “Device or resource busy” means consumers remain. Any mounted partition, open file, running VM, or loop mapping blocks the unmount step. Find holders (fuser -vm, lsof +D, findmnt), close them, retry. -m skips the unmount and asks the drive directly — which usually fails on mounted media.
• USB sticks: “eject” vs power-off. On Linux, ejecting a USB mass-storage device spins it down/flushes it but the device may remain enumerated; the desktop “safely remove” additionally powers the port off (udisks power-off). Either way, data is flushed before the tray/eject step — but do not unplug while a filesystem is mounted.
• Tray-less and exotic drives. -t fails on slot-loaders; some cheap USB enclosures ignore eject ioctls entirely; -X returns nothing on drives that do not implement speed reporting.
• Permissions. Eject ioctls generally work for unprivileged users on drives with sane udev ACLs (the logged-in session), but tapes, changers and non-session devices usually need root.
• -i on locks the hardware button too. Forgetting it engaged is a classic support call (“the tray button stopped working”) — eject -i off unlocks.
• Resolution surprises. A mountpoint argument resolves through the mount table; on automounted/autofs paths the mount may be indirect — verify with -n first.
• Package provenance. Debian splits it out of the main util-linux binary package; minimal containers often lack it while shipping umount.

Exit Status

Related Commands

• overview — index of all util-linux collection pages
• permissions — who may issue device ioctls and why (udev ACLs, groups)

Interview Questions

Q: What is the difference between eject and umount on Linux?

umount only detaches the filesystem. eject resolves a mountpoint or device, unmounts everything mounted from it (including sibling partitions), and then issues the drive-level eject ioctl — tray opens, tape unloads, or the device spins down. On USB media, desktop stacks go one step further and power off the device after ejecting.

Q: A user runs eject /dev/sdb1 and gets “device is busy”. Walk through triage.

First list what is mounted from the device (findmnt /dev/sdb1 and siblings), then find processes holding files open (fuser -vm <mountpoint>, lsof +D <mountpoint>), including non-obvious consumers: shells with cwd inside, search indexers, VMs with the disk attached. Terminate or stop them, unmount, retry. eject -m would bypass the unmount but typically cannot eject while a filesystem is mounted, so closing consumers is the real fix.

Q: What does eject -i on do, and when is it useful?

It engages the drive’s software eject lock, which makes both the physical eject button and software ejects fail until -i off is issued. It protects mounted media from being yanked — e.g. museum/kiosk machines or racks where users press tray buttons — at the cost of a support call when someone forgets it is set.

Q: How does eject resolve a mountpoint argument to a device?

It consults the kernel’s mount table (mountinfo) to find the device backing the given path, then targets the whole drive. eject -n prints that resolution without acting, which is why it doubles as a scripting helper for turning paths into device names. Recent versions extend this to unmount all partitions of the resolved device, not just the one named.

Q: Where does the Debian eject binary come from and why does that matter for availability?

Bookworm builds it from the util-linux source tree into a separate eject package (upstream merged the old standalone eject in 2.38). Practical consequence: minimal images and slim containers frequently lack eject while having umount, so scripts should fall back gracefully or use udisksctl power-off in desktop contexts.

References

• Man page(1) — manpages.debian.org
• Source — GitHub
• Source — Debian sources