mount, umount - mount and unmount filesystems.
SYNOPSIS
#include <sys/mount.h>
int mount(const char *specialfile, const char * dir ,
const char * filesystemtype, unsigned long mountflags ,
const void * data);
int umount(const char *dir);
DESCRIPTION
mount attaches the filesystem specified by specialfile
(which is often a device name) to the directory specified
by dir.
umount removes the attachment of the (topmost) filesystem
mounted on dir.
Only the super-user may mount and unmount filesystems.
The filesystemtype argument may take one of the values
listed in /proc/filesystems (like "minix", "ext2",
"msdos", "proc", "nfs", "iso9660" etc.).
The mountflags argument may have the magic number 0xC0ED
in the top 16 bits, and various mount flags (as defined in
<linux/fs.h> for libc4 and libc5 and in <sys/mount.h> for
glibc2) in the low order 16 bits:
#define MS_RDONLY 1 /* mount read-only */
#define MS_NOSUID 2 /* ignore suid and sgid bits */
#define MS_NODEV 4 /* no access to device special files */
#define MS_NOEXEC 8 /* no program execution */
#define MS_SYNCHRONOUS 16 /* writes are synced at once */
#define MS_REMOUNT 32 /* alter flags of a mounted fs */
#define MS_MANDLOCK 64 /* allow mandatory locks */
#define MS_NOATIME 1024 /* do not update access times */
#define MS_NODIRATIME 2048 /* do not update dir access times */
#define MS_BIND 4096 /* bind subtree elsewhere */
The data argument is interpreted by the different file
systems.
RETURN VALUE
On success, zero is returned. On error, -1 is returned,
and errno is set appropriately.
ERRORS
The error values given below result from filesystem type
independent errors. Each filesystem type may have its own
special errors and its own special behavior. See the
EPERM The user is not the super-user.
ENODEV Filesystemtype not configured in the kernel.
ENOTBLK
Specialfile is not a block device (if a device was
required).
EBUSY Specialfile is already mounted. Or, it cannot be
remounted read-only, because it still holds files
open for writing. Or, it cannot be mounted on dir
because dir is still busy (it is the working direc
tory of some task, the mount point of another
device, has open files, etc.).
EINVAL Specialfile had an invalid superblock. Or, a
remount was attempted, while specialfile was not
already mounted on dir. Or, an umount was
attempted, while dir was not a mount point.
EFAULT One of the pointer arguments points outside the
user address space.
ENOMEM The kernel could not allocate a free page to copy
filenames or data into.
ENAMETOOLONG
A pathname was longer than MAXPATHLEN.
ENOENT A pathname was empty or had a nonexistent compo
nent.
ENOTDIR
The second argument, or a prefix of the first argu
ment, is not a directory.
EACCES A component of a path was not searchable.
Or, mounting a read-only filesystem was attempted
without giving the MS_RDONLY flag.
Or, the block device Specialfile is located on a
filesystem mounted with the MS_NODEV option.
ENXIO The major number of the block device specialfile is
out of range.
EMFILE (In case no block device is required:) Table of
dummy devices is full.
CONFORMING TO
These functions are Linux-specific and should not be used
in programs intended to be portable.
The original umount function was called as umount(device)
and would return ENOTBLK when called with something other
than a block device. In Linux 0.98p4 a call umount(dir)
was added, in order to support anonymous devices. In
Linux 2.3.99-pre7 the call umount(device) was removed,
leaving only umount(dir) (since now devices can be mounted
in more than one place, so specifying the device does not
suffice).
The original MS_SYNC flag was renamed MS_SYNCHRONOUS in
1.1.69 when a different MS_SYNC was added to <mman.h>.
SEE ALSO
mount(8), umount(8)
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