mount(1M) UNIX System V(NFS) mount(1M)
NAME
mount - mount remote NFS resources
SYNOPSIS
mount [-F nfs] [-r] [-o specific_options] {resource | mountpoint}
mount [-F nfs] [-r] [-o specific_options] resource mountpoint
DESCRIPTION
The mount command attaches a named resource to the file system hierarchy
at the pathname location mountpoint, which must already exist. If
mountpoint has any contents prior to the mount operation, the contents
remain hidden until the resource is once again unmounted.
If the resource is listed in the vfstab file, the command line can
specify either resource or mountpoint, and mount will consult vfstab for
more information. If the -F option is omitted, mount will take the file
system type from vfstab.
mount maintains a table of mounted file systems in /etc/mnttab, described
in mnttab(4).
The following options are available to the mount command:
-r Mount the specified file system read-only.
-o Specify the nfs file-specific options in a comma-separated list.
The available options are:
rw|ro resource is mounted read-write or read-only. The
default is rw.
suid|nosuid Setuid execution allowed or disallowed. The default
is suid.
remount If a file system is mounted read-only, remounts the
file system read-write.
bg|fg If the first attempt fails, retry in the background,
or, in the foreground. The default is fg.
retry=n The number of times to retry the mount operation.
The default is 10000.
port=n The server IP port number. The default is NFSPORT.
grpid Create a file with its GID set to the effective GID
of the calling process. This behavior may be
overridden on a per-directory basis by setting the
set-GID bit of the parent directory; in this case,
the GID is set to the GID of the parent directory
[see open(2) and mkdir(2)]. Files created on file
systems that are not mounted with the grpid option
will obey BSD semantics; that is, the GID is
unconditionally inherited from that of the parent
directory.
rsize=n Set the read buffer size to n bytes.
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wsize=n Set the write buffer size to n bytes.
timeo=n Set the NFS timeout to n tenths of a second.
retrans=n Set the number of NFS retransmissions to n.
soft|hard Return an error if the server does not respond, or
continue the retry request until the server responds.
intr Allow keyboard interrupts to kill a process that is
hung while waiting for a response on a hard-mounted
file system.
secure Use a more secure protocol for NFS transactions.
noac Suppress attribute caching.
acregmin=n Hold cached attributes for at least n seconds after
file modification.
acregmax=n Hold cached attributes for no more than n seconds
after file modification.
acdirmin=n Hold cached attributes for at least n seconds after
directory update.
acdirmax=n Hold cached attributes for no more than n seconds
after directory update.
actimeo=n Set min and max times for regular files and
directories to n seconds.
NFS FILE SYSTEMS
Background vs. Foreground
File systems mounted with the bg option indicate that mount is to retry
in the background if the server's mount daemon [mountd(1M)] does not
respond. mount retries the request up to the count specified in the
retry=n option. Once the file system is mounted, each NFS request made
in the kernel waits timeo=n tenths of a second for a response. If no
response arrives, the time-out is multiplied by 2 and the request is
retransmitted. When the number of retransmissions has reached the number
specified in the retrans=n option, a file system mounted with the soft
option returns an error on the request; one mounted with the hard option
prints a warning message and continues to retry the request.
Read-Write vs. Read-Only
File systems that are mounted rw (read-write) should use the hard option.
Secure File Systems
The secure option must be given if the server requires secure mounting
for the file system.
File Attributes
The attribute cache retains file attributes on the client. Attributes
for a file are assigned a time to be flushed. If the file is modified
before the flush time, then the flush time is extended by the time since
the last modification (under the assumption that files that changed
recently are likely to change soon). There is a minimum and maximum
flush time extension for regular files and for directories. Setting
actimeo=n extends flush time by n seconds for both regular files and
directories.
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EXAMPLES
To mount a remote file system: mount -F nfs serv:/usr/src /usr/src
To hard mount a remote file system: mount -o hard serv:/usr/src /usr/src
FILES
/etc/mnttab mount table
/etc/dfs/fstypes default distributed file system type
/etc/vfstab table of automatically mounted resources
SEE ALSO
mountall(1M), mount(2), umount(2), mnttab(4).
NOTES
If the directory on which a file system is to be mounted is a symbolic
link, the file system is mounted on the directory to which the symbolic
link refers, rather than being mounted on top of the symbolic link
itself.
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