umount(2)

NAME

umount(), umount2() — unmount a file system

SYNOPSIS

#include <sys/mount.h>

int umount(const char *name);

int umount2(const char *name, int flags);

DESCRIPTION

umount() requests that a previously mounted file system contained on the block special device identified by name be unmounted.

umount2() requests that a previously mounted file system contained on the block special device identified by name be unmounted in the manner described in flags.

name is a pointer to a path name.

flags is a bitmask of flags, specified in <sys/mount.h>, that are combined to describe the type of unmount to be performed. Valid flags are:

MS_NORMAL: perform a normal unmount
MS_FORCE: perform a forced unmount

MS_NORMAL and MS_FORCE are mutually exclusive.

A forced unmount is one which will occur regardless of activity on the file system.

After unmounting the file system, the directory upon which the file system was mounted reverts to its ordinary interpretation.

umount() and umount2() can also request that a file system mounted previously on the directory identified by name be unmounted. After unmounting the file system, name reverts to its ordinary interpretation.

umount() and umount2() can be invoked only by the user with the appropriate privilege.

NETWORKING FEATURES

NFS

path must indicate a directory name when unmounting an NFS file system.

RETURN VALUE

If successful, umount() and umount2() return a value of 0. Otherwise, they return a value of -1 and set errno to indicate the error.

ERRORS

umount() and umount2() fail if one or more of the following are true:

EACCES: A component of the path prefix of name denies search permission.
EBUSY: A file on name is busy.
EFAULT: name points outside the allocated address space of the process. Reliable detection of this error is implementation dependent.
EINVAL: name is not mounted.
EINVAL: flags is not a valid combination of flags.
ELOOP: Too many symbolic links were encountered in translating the path name.
ENAMETOOLONG: name exceeds PATH_MAX bytes, or a component of name exceeds NAME_MAX bytes while _POSIX_NO_TRUNC is in effect.
ENOENT: name does not exist.
ENOENT: name is null.
ENOSYS: A forced unmount was requested on a file system that does not support it.
ENOTBLK: name is not a block special device.
ENOTDIR: A component of name is not a directory.
ENXIO: The device associated with name does not exist.
EPERM: The effective user ID of the process is not that of a user with appropriate privileges.

STANDARDS CONFORMANCE

umount(): SVID2, SVID3, XPG2

umount(2)

Technical documentation

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