| MOUNT(8) | System Manager's Manual | MOUNT(8) | 
mount —
| mount | [ -Aadfruvw] [-ttype] | 
| mount | [ -dfruvw] {special |
      node} | 
| mount | [ -dfruvw] [-ooptions] [-ttype] special node | 
mount command invokes a file system-specific program
  to prepare and graft the special device on to the file
  system tree at the point node, or to update options for
  an already-mounted file system.
These programs are named “mount_<fstype>” where “<fstype>” refers to the file system-specific type; for example for NFS the mount program is called mount_nfs(8).
The node argument is always interpreted as a directory in the name space of currently mounted file systems. The special argument is interpreted in different ways by the programs that handle different file system types; for example, mount_ffs(8) interprets it as a device node, mount_null(8) interprets it as a directory name, mount_nfs(8) interprets it as reference to a remote host and a directory on that host, and mount_tmpfs(8) ignores it.
The system maintains a list of currently mounted file systems.
    This list is printed if mount is invoked with no
    arguments, and with no options that require some other behaviour.
If exactly one of special or
    node is provided, then the missing information
    (including the file system type) is taken from the
    fstab(5) file. The provided
    argument is looked up first in the “fs_file”, then in the
    “fs_spec” column. If the matching entry in
    fstab(5) has the string
    “from_mount” as its
    “fs_spec” field, the device or remote file system already
    mounted at the location specified by “fs_spec” will be
  used.
If both special and
    node are provided, then
    fstab(5) is not used. In this
    case, if the file system type is not specified via the
    -t flag, then mount may
    determine the type from the disk label (see
    disklabel(8)). In addition,
    if special contains a colon
    (‘:’) or at sign
    (‘@’), then the
    nfs type is inferred. In
    NetBSD, the file system mounting policy is dictated
    by the running security models. The default security model may allow
    unprivileged mounting; see
    secmodel_suser(9) and
    secmodel_extensions(9)
    for details.
The options are as follows:
-Amount to try to mount all of the file
      systems listed in the
      fstab(5) file except those
      for which the “noauto” option is specified.-a-A flag, except that if a file
      system (other than the root file system) appears to be already mounted,
      mount will not try to mount it again.
      mount assumes that a file system is already
      mounted if a file system with the same type is mounted on the given mount
      point. More stringent checks are not possible because some file system
      types report strange values for the mounted-from device for mounted file
      systems.-d-v flag to determine what the
      mount command is trying to do.-f-o-o flag followed by a
      comma separated string of options. The following options are available:
    asyncnoasyncasync mode.automounteddiscardEXPERIMENTAL - negatively influences
            filesystem performance by increasing fragmentation, causes free
            block map inconsistency on unclean shutdown, and is incompatible
            with log. If log
            option is also used, discard is
            automatically disabled.
extattrforce-f; forces the revocation of write
          access when trying to downgrade a file system mount status from
          read-write to read-only.getargsMNT_IGNORE flag, causes the
          mount point to be excluded from the list of file systems shown by
          default with df(1).noatimenoauto-a flag.nocoredumpnodevnodevmtimenoexecnosuidportrdonly-r; mount the file system
          read-only (even the super-user may not write it).reloadrump-t flag and respective rump_type manual page
          for more information.logWAPBL option
          to be enabled in the running kernel. See
          wapbl(4) for more
          information. This option requires the “UFS2” (level 4)
          superblock layout, which is the default for newly created FFSv1 and
          FFSv2 file systems. To update an old file system with an earlier
          superblock format, use the -c option of
          fsck_ffs(8).
        log cannot be used together with
            discard.
A file system mounted with log can
            be mounted also with async, but such
            filesystem behaves the same as if async was
            not specified - meta-data writes use the log, hence its integrity is
            still guaranteed.
sympermsyncnosyncsync mode.unionNote that the union option can be
            applied to any type of file system, and is fundamentally different
            from
            mount_union(8),
            which is a particular type of file system. Also note that the
            union option affects the file system name
            space only at the mount point itself; it does not apply recursively
            to subdirectories.
update-u; indicate that the status of an
          already mounted file system should be changed.Any additional options specific to a given file system type
        (see the -t option) may be passed as a comma
        separated list; these options are distinguished by a leading
        “-” (dash). Options that take a value are specified using
        the syntax -option=value. For example, the mount command:
mount -t mfs -o nosuid,-N,-s=32m swap /tmp
    
    causes mount to execute the equivalent
        of:
/sbin/mount_mfs -o nosuid -N -s 32m swap /tmp
    
    -r-o
    option.-t
    type-t is used to indicate
      the file system type. The type ffs is the default.
      The -t option can be used to indicate that the
      actions should only be taken on file systems of the specified type. More
      than one type may be specified in a comma separated list. The list of file
      system types can be prefixed with “no” to specify the file
      system types for which action should not be taken. For
      example, the mount command:
    
mount -a -t nonfs,mfs
    
    mounts all file systems except those of type NFS and MFS.
mount will attempt to execute a
        program in /sbin/mount_XXX
        where XXX is replaced by the type name. For example,
        nfs file systems are mounted by the program
        /sbin/mount_nfs.
-u-u flag indicates that the status of an
      already mounted file system should be changed. Any of the options
      discussed above (the -o option) may be changed;
      also a file system can be changed from read-only to read-write or vice
      versa. An attempt to change from read-write to read-only will fail if any
      files on the file system are currently open for writing unless the
      -f flag is also specified. The set of options is
      determined by first extracting the options for the file system from the
      fstab(5) file, then applying
      any options specified by the -o argument, and
      finally applying the -r or
      -w option.-v-wThe options specific to the various file system types are described in the manual pages for those file systems' “mount_<fstype>” commands; for instance, the options specific to Berkeley Fast File System (FFS) are described in the mount_ffs(8) manual page.
The particular type of file system in each partition of a disk can be found by examining the disk label with the disklabel(8) command.
The “noauto” directive in /etc/fstab can be used to make it easy to manually mount and unmount removable media using just the mountpoint filename, with an entry like this:
/dev/cd0a /cdrom cd9660 ro,noauto 0
  0That would allow a simple command like “mount /cdrom” or “umount /cdrom” for media using the ISO-9660 file system format in the first CD-ROM drive.
The error “Operation not permitted” may indicate that the mount options include privileged options and/or do not include options that exclude privileged options. One should try using at least “nodev” and “nosuid” in such cases:
mount -t cd9660 -o nodev,nosuid /dev/cd0a /mnt
mount command appeared in
  Version 1 AT&T UNIX.
| July 10, 2022 | NetBSD 10.0 |