umount

Additional Notes

umount is a disk and filesystem command used to detach a mounted filesystem. It detaches a mounted filesystem from the directory tree, making the underlying storage safe to remove.

If unmounting fails with 'target is busy', use fuser -m /mountpoint or lsof /mountpoint to find blocking processes.

Syntax

umount [options] [device-or-path]

Parameters

• options: Flags that change how umount behaves.
• device: Disk, partition, volume, or filesystem path to inspect or modify.
• target: Mount point, file, or storage object used by the operation.

Common Options

• -l: Lazy unmount.
• -f: Force unmount where supported.
• -a: Unmount filesystems from /etc/mtab.

Examples

sudo umount /mnt/usb
sudo umount /dev/sdb1
sudo umount -l /mnt/busy

Practical Notes

If unmounting fails because the target is busy, check for open files or shells currently inside the mount point.