• NAME
  
  mount - mount file system
• SYNOPSIS
  

  
   "#include <sys/mount.h>"
  
   int mount(const char * source , const char * target ,
              const char * filesystemtype , unsigned long  mountflags ,             const void * data ); 

• DESCRIPTION
  
  mount ()
  attaches the file system specified by
  source
  (which is often a device name, but can also be a directory name
  or a dummy) to the directory specified by
  target .
  
  Appropriate privilege (Linux: the
  CAP_SYS_ADMIN capability) is required to mount file systems.
  
  Since Linux 2.4 a single file system can be visible at
  multiple mount points, and multiple mounts can be stacked
  on the same mount point.
  
  
  Values for the
  filesystemtype
  argument supported by the kernel are listed in
  /proc/filesystems
  (like "minix", "ext2", "ext3", "jfs", "xfs", "reiserfs",
  "msdos", "proc", "nfs", "iso9660" etc.).
  Further types may become available when the appropriate modules
  are loaded.
  
  The
  mountflags
  argument may have the magic number 0xC0ED (MS_MGC_VAL)
  in the top 16 bits (this was required in kernel versions prior to 2.4, but
  is no longer required and ignored if specified),
  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:
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

  MS_BIND " (Linux 2.4 onwards)"
  

  
  Perform a bind mount, making a file or a directory subtree visible at
  another point within a file system.
  Bind mounts may cross file system boundaries and span
  chroot(2)
  jails.
  The
  filesystemtype
  and
  data
  arguments are ignored.
  Up until Linux 2.6.26,
  mountflags
  was also ignored
  
  (the bind mount has the same mount options as
  the underlying mount point).
  Since Linux 2.6.26, the
  MS_RDONLY flag is honored when making a bind mount.
  

  MS_DIRSYNC " (since Linux 2.5.19)"
  

  Make directory changes on this file system synchronous.
  (This property can be obtained for individual directories
  or subtrees using
  chattr(1) .)
  

  MS_MANDLOCK

  Permit mandatory locking on files in this file system.
  (Mandatory locking must still be enabled on a per-file basis,
  as described in
  fcntl(2) .)
  
  

  MS_MOVE

  Move a subtree.
  source
  specifies an existing mount point and
  target
  specifies the new location.
  The move is atomic: at no point is the subtree unmounted.
  The
  filesystemtype ", " mountflags ", and " data
  arguments are ignored.
  

  MS_NOATIME

  Do not update access times for (all types of) files on this file system.
  

  MS_NODEV

  Do not allow access to devices (special files) on this file system.
  

  MS_NODIRATIME

  Do not update access times for directories on this file system.
  This flag provides a subset of the functionality provided by
  MS_NOATIME ;
  that is,
  MS_NOATIME
  implies
  MS_NODIRATIME .
  

  MS_NOEXEC

  Do not allow programs to be executed from this file system.
  
  
  
  

  MS_NOSUID

  Do not honor set-user-ID and set-group-ID bits when executing
  programs from this file system.
  
  
  

  MS_RDONLY

  Mount file system read-only.
  
  
  
  
  

  MS_RELATIME " (Since Linux 2.6.20)"
  

  When a file on this file system is accessed,
  only update the file's last access time (atime) if the current value
  of atime is less than or equal to the file's last modification time (mtime)
  or last status change time (ctime).
  This option is useful for programs, such as
  mutt(1) ,
  that need to know when a file has been read since it was last modified.
  

  MS_REMOUNT

  Remount an existing mount.
  This allows you to change the
  mountflags
  and
  data
  of an existing mount without having to unmount and remount the file system.
  source
  and
  target
  should be the same values specified in the initial
  mount ()
  call;
  filesystemtype
  is ignored.
  
  The following
  mountflags
  can be changed:
  MS_RDONLY ,
  MS_SYNCHRONOUS ,
  MS_MANDLOCK ;
  before kernel 2.6.16, the following could also be changed:
  MS_NOATIME and
  MS_NODIRATIME ;
  and, additionally, before kernel 2.4.10, the following could also be changed:
  MS_NOSUID ,
  MS_NODEV ,
  MS_NOEXEC .
  

  MS_SILENT " (since Linux 2.6.17)"
  

  Suppress the display of certain
  ( printk ()) warning messages in the kernel log.
  This flag supersedes the misnamed and obsolete
  MS_VERBOSE
  flag (available since Linux 2.4.12), which has the same meaning.
  

  MS_SYNCHRONOUS

  Make writes on this file system synchronous (as though
  the
  O_SYNC flag to
  open(2)
  was specified for all file opens to this file system).
  
  
  
  From Linux 2.4 onwards, the
  MS_NODEV ", " MS_NOEXEC ", and " MS_NOSUID
  flags are settable on a per-mount-point basis.
  From kernel 2.6.16 onwards,
  MS_NOATIME and
  MS_NODIRATIME are also settable on a per-mount-point basis.
  The
  MS_RELATIME flag is also settable on a per-mount-point basis.
  
  
  
  The
  data
  argument is interpreted by the different file systems.
  Typically it is a string of comma-separated options
  understood by this file system.
  See
  mount(8)
  for details of the options available for each filesystem type.
  

• 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.
  

  EACCES

  A component of a path was not searchable.
  (See also
  path_resolution(7) .)
  Or, mounting a read-only filesystem was attempted without giving the
  MS_RDONLY flag.
  Or, the block device
  source
  is located on a filesystem mounted with the
  MS_NODEV option.
  
  
  

  EBUSY

  source
  is already mounted.
  Or, it cannot be remounted read-only,
  because it still holds files open for writing.
  Or, it cannot be mounted on
  target
  because
  target
  is still busy (it is the working directory of some task,
  the mount point of another device, has open files, etc.).
  

  EFAULT

  One of the pointer arguments points outside the user address space.
  

  EINVAL

  source
  had an invalid superblock.
  Or, a remount
  was attempted, but
  source
  was not already mounted on
  target .
  Or, a move
  was attempted, but
  source
  was not a mount point, or was (aq/(aq.
  

  ELOOP

  Too many links encountered during pathname resolution.
  Or, a move was attempted, while
  target
  is a descendant of
  source .
  

  EMFILE

  (In case no block device is required:)
  Table of dummy devices is full.
  

  ENAMETOOLONG

  A pathname was longer than
  MAXPATHLEN .
  

  ENODEV

  filesystemtype
  not configured in the kernel.
  

  ENOENT

  A pathname was empty or had a nonexistent component.
  

  ENOMEM

  The kernel could not allocate a free page to copy filenames or data into.
  

  ENOTBLK

  source
  is not a block device (and a device was required).
  

  ENOTDIR

  target ,
  or a prefix of
  source ,
  is not a directory.
  

  ENXIO

  The major number of the block device
  source
  is out of range.
  

  EPERM

  The caller does not have the required privileges.
  

• CONFORMING TO
  
  This function is Linux-specific and should not be used in
  programs intended to be portable.
  
• NOTES
  
  The original
  MS_SYNC flag was renamed
  MS_SYNCHRONOUS in 1.1.69
  when a different
  MS_SYNC was added to <mman.h>.
  
  Before Linux 2.4 an attempt to execute a set-user-ID or set-group-ID program
  on a filesystem mounted with
  MS_NOSUID would fail with
  EPERM .
  Since Linux 2.4 the set-user-ID and set-group-ID bits are
  just silently ignored in this case.
  
  Per-process Namespaces
  Starting with kernel 2.4.19, Linux provides
  per-process mount namespaces.
  A mount namespace is the set of file system mounts that
  are visible to a process.
  Mount-point namespaces can be (and usually are)
  shared between multiple processes,
  and changes to the namespace (i.e., mounts and unmounts) by one process
  are visible to all other processes sharing the same namespace.
  (The pre-2.4.19 Linux situation can be considered as one in which there
  was a single namespace was shared by every process on the system.)
  
  A child process created by
  fork(2)
  shares its parent's mount namespace;
  the mount namespace is preserved across an
  execve(2) .
  
  A process can obtain a private mount namespace if:
  it was created using the
  clone ()
  CLONE_NEWNS
  flag,
  in which case its new namespace is initialized to be a
  copy
  of the namespace of the process that called
  clone ();
  or it calls
  unshare(2)
  with the
  CLONE_NEWNS
  flag,
  which causes the caller's mount namespace to obtain a private copy
  of the namespace that it was previously sharing with other processes,
  so that future mounts and unmounts by the caller are invisible
  to other processes (except child processes that the caller
  subsequently creates) and vice versa.
  
  The Linux-specific
  /proc/PID/self
  file exposes the list of mount points in the mount
  namespace of the process with the specified ID; see
  proc(5)
  for details.
  
• SEE ALSO
  
  umount(2) ,
  path_resolution(7) ,
  mount(8) ,
  umount(8)
  
• COLOPHON
  
  This page is part of release 3.19 of the Linux
  man-pages
  project.
  A description of the project,
  and information about reporting bugs,
  can be found at
  http://www.kernel.org/doc/man-pages/.
  

Current Users: 89 © 1999-2009 PenguinSoft. All trademarks and copyrights on this page are owned by their respective companies. Linux is a trademark of Linus Torvalds.