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Name

mount - mount a file system

Synopsis


#include <sys/types.h>
#include <sys/mount.h>

int mount(const char *spec, const char *dir, int mflag, /* char *fstype, const char *dataptr, int datalen */ ...);

Description

mount() requests that a removable file system contained on the block special file identified by spec be mounted on the directory identified by dir. spec and dir are pointers to path names. fstype is the file system type, which can be determined by the sysfs(2) function. If both the MS_DATA and MS_FSS flag bits of mflag are off, the file system type defaults to the root file system type. Only if either flag is on is fstype used to indicate the file system type.

If the MS_DATA flag is set in mflag the system expects the dataptr and datalen arguments to be present. Together they describe a block of file-system specific data at address dataptr of length datalen. This is interpreted by file-system specific code within the operating system and its format depends on the file system type. If a particular file system type does not require this data, dataptr and datalen should both be zero. Note that MS_FSS is obsolete and is ignored if MS_DATA is also set, but if MS_FSS is set and MS_DATA is not, dataptr and datalen are both assumed to be zero.

After a successful call to mount(), all references to the file dir refer to the root directory on the mounted file system.

The low-order bit of mflag is used to control write permission on the mounted file system: if 1, writing is forbidden; otherwise writing is permitted according to individual file accessibility.

The mount() system call may only be invoked only by processes with super-user privileges.

Return Values

Upon successful completion a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error.

Errors

mount() fails if one or more of the following are true:

EBUSY
dir is currently mounted on, is someone’s current working directory, or is otherwise busy.
EBUSY
The device associated with spec is currently mounted.
EBUSY
There are no more mount table entries.
EFAULT
spec, dir, or datalen points outside the allocated address space of the process.
EINVAL
The super block has an invalid magic number or the fstype is invalid.
ELOOP
Too many symbolic links were encountered in translating spec or dir.
EMULTIHOP
Components of path require hopping to multiple remote machines and the file system type does not allow it.
ENAMETOOLONG
The length of the path argument exceeds {PATH_MAX }, or the length of a path component exceeds {NAME_MAX } while {_POSIX_NO_TRUNC } is in effect.
ENOENT
None of the named files exists or is a null pathname.
ENOTBLK
spec is not a block special device.
ENOTDIR
dir is not a directory.
ENOTDIR
A component of a path prefix is not a directory.
EPERM
The effective user ID is not super-user.
EREMOTE
spec is remote and cannot be mounted.
ENOLINK
path points to a remote machine and the link to that machine is no longer active.
ENXIO
The device associated with spec does not exist.
EROFS
spec is write protected and mflag requests write permission.
ENOSPC
The file system state in the super-block is not FsOKAY and mflag requests write permission.

See Also

mount(1M) , sysfs(2) , umount(2)

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