MOUNT

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
CONFORMING TO
SEE ALSO

NAME

mount, umount − mount and unmount filesystems.

SYNOPSIS

#include <sys/mount.h>

int mount(const char *specialfile, const char * dir , const char * filesystemtype, unsigned long rwflag , const void * data);

int umount(const char *specialfile);

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 filesystem specified by specialfile or 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 rwflag argument has 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 /* disallow access to device special files */
#define MS_NOEXEC    8 /* disallow program execution */
#define MS_SYNC     16 /* writes are synced at once */
#define MS_REMOUNT  32 /* alter flags of a mounted FS */
#define MS_MGC_VAL 0xC0ED0000

If the magic number is absent, then the last two arguments are not used.

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 kernel source code for details.

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 directory 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 component.

ENOTDIR

The second argument, or a prefix of the first argument, 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.

SEE ALSO

mount(8), umount(8)