umount(2) System Calls umount(2)NAME
umount, umount2 - unmount a file system
SYNOPSIS
#include <sys/mount.h>
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 absolute 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.
MS_FORCE 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 unsuc‐
cessful. The umount2() function returns ENOTSUP if the
specified file systems does not support MS_FORCE. Cur‐
rently only nfs- and ufs-type file systems support
MS_FORCE.
RETURN VALUES
Upon successful completion, 0 is returned. Otherwise, −1 is returned
and errno is set to indicate the error.
ERRORS
The umount() and umount2() functions will fail if:
EACCES The permission bits of the mount point do not
permit read/write access or search 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 ille‐
gal address.
EINVAL The file pointed to by file is not mounted.
ELOOP Too many symbolic links were encountered in
translating the path pointed to by file.
ENAMETOOLONG The length of the file argument exceeds
PATH_MAX, or the length of a file component
exceeds NAME_MAX while _POSIX_NO_TRUNC 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machine and the link to that machine is no
longer active.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 spe‐
cial device.
EPERM The {PRIV_SYS_MOUNT} privilege is not asserted
in the effective set of the calling process.
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 {PRIV_SYS_MOUNT} privilege asserted in its effective set.
Because it provides greater functionality, the umount2() function is
preferred.
SEE ALSOmount(2), privileges(5)SunOS 5.10 22 Mar 2004 umount(2)
