umount

Unmount filesystems or partitions (UNIX)

Syntax:

umount block_special_file

umount mount_point

Options:

block_special_file

The name of a block special file.

mount_point

The mount point of a QNX filesystem.

Description:

The umount utility unmounts filesystems (i.e. mount points) or partitions mounted on the named block special file.

Once you unmount a filesystem, you can't access files on that partition -- including the mount utility if you are getting your commands from the partition you just unmounted. Unless you have access to the mount utility on another disk (possibly a floppy), you will be unable to remount the filesystem.

Executing umount will fail if the named file isn't a mount point. It will also fail if the block special file is not mounted or if it is busy (a filesystem is busy if there are any files in use).

Since it effectively functions like sync, but doesn't return until all the filesystem data has been successfully updated, you should execute umount on floppy devices or other removable media before removing the disk (or diskette) from the drive. This will help prevent unusual errors or possible file corruption.

Examples:

Unmount a filesystem mounted on your primary QNX partition:

    umount /dev/hd0t77

Unmount all partitions mounted on your primary hard disk:

    umount /dev/hd0

Mount a read-only floppy filesystem, unmount it, and remount it as a read/write filesystem:

    mount /dev/fd0 /floppy -r
    umount /floppy
    mount /dev/fd0 /floppy

See also:

mount, sync