System Calls umount(2)
NAME
umount, umount2 - unmount a file system
SYNOPSIS
#include
int umount(const char *file);
int umount2(const char *file, int mflag);
DESCRIPTION
The umount() function requests that a previously mounted
file system contained on a block special device or directory
be unmounted. The file argument is a pointer to the abso-
lute pathname of the file system to be unmounted. After
unmounting the file system, the directory upon which the
file system was mounted reverts to its ordinary interpreta-
tion.
The umount2() function is identical to umount(), with the
additional capability of unmounting file systems even if
there are open files active. The mflag argument must contain
one of the following values:
0 Perform a normal unmount that is equivalent to
umount(). The umount2() function returns EBUSY
if there are open files active within the file
system to be unmounted.
MSFORCE Unmount the file system, even if there are open
files active. A forced unmount can result in
loss of data, so it should be used only when a
regular unmount is unsuccessful. The umount2()
function returns ENOTSUP if the specified file
systems does not support MSFORCE. Only file
systems of type nfs, ufs, pcfs, and zfs support
MSFORCE.
RETURN VALUES
Upon successful completion, 0 is returned. Otherwise, -1 is
returned and errno is set to indicate the error.
ERORS
The umount() and umount2() functions will fail if:
EACES The permission bits of the mount point do
not permit read/write access or search
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System Calls umount(2)
permission is denied on a component of the
path prefix.
The calling process is not the owner of the
mountpoint.
The mountpoint is not a regular file or a
directory and the caller does not have all
privileges available in a its zone.
The special device device does not permit
read access in the case of read-only mounts
or read-write access in the case of
read/write mounts.
EBUSY A file on file is busy.
EFAULT The file pointed to by file points to an
illegal address.
EINVAL The file pointed to by file is not mounted.
ELOP Too many symbolic links were encountered in
translating the path pointed to by file.
ENAMETOLONG The length of the file argument exceeds
PATHMAX, or the length of a file component
exceeds NAMEMAX while POSIXNOTRUNC is in
effect.
ENOENT The file pointed to by file does not exist
or is not an absolute path.
ENOLINK The file pointed to by file is on a remote
machine and the link to that machine is no
longer active.
ENOTBLK The file pointed to by file is not a block
special device.
EPERM The {PRIVSYSMOUNT} privilege is not
asserted in the effective set of the calling
process.
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System Calls umount(2)
EREMOTE The file pointed to by file is remote.
The umount2() function will fail if:
ENOTSUP The file pointed to by file does not support this
operation.
USAGE
The umount() and umount2() functions can be invoked only by
a process that has the {PRIVSYSMOUNT} privilege asserted
in its effective set.
Because it provides greater functionality, the umount2()
function is preferred.
SEE ALSO
mount(2), privileges(5)
SunOS 5.11 Last change: 4 Aug 2008 3
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