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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | CAVEATS / WORKAROUNDS | MOUNTING FROM /ETC/FSTAB | SEE ALSO | GETTING HELP | AUTHORS | COLOPHON |
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SSHFS(1) User Commands SSHFS(1)
SSHFS - filesystem client based on SSH
To mount a filesystem:
sshfs [user@]host:[dir] mountpoint [options]
If host is a numeric IPv6 address, it needs to be enclosed in
square brackets.
To unmount it:
fusermount3 -u mountpoint # Linux
umount mountpoint # OS X, FreeBSD
SSHFS allows you to mount a remote filesystem using SSH (more
precisely, the SFTP subsystem). Most SSH servers support and
enable this SFTP access by default, so SSHFS is very simple to
use - there's nothing to do on the server-side.
By default, file permissions are ignored by SSHFS. Any user that
can access the filesystem will be able to perform any operation
that the remote server permits - based on the credentials that
were used to connect to the server. If this is undesired, local
permission checking can be enabled with -o default_permissions.
By default, only the mounting user will be able to access the
filesystem. Access for other users can be enabled by passing -o
allow_other. In this case you most likely also want to use -o
default_permissions.
It is recommended to run SSHFS as regular user (not as root).
For this to work the mountpoint must be owned by the user. If
username is omitted SSHFS will use the local username. If the
directory is omitted, SSHFS will mount the (remote) home
directory. If you need to enter a password sshfs will ask for it
(actually it just runs ssh which ask for the password if needed).
-o opt,[opt...]
mount options, see below for details. A a variety of SSH
options can be given here as well, see the manual pages
for sftp(1) and ssh_config(5).
-h, --help
print help and exit.
-V, --version
print version information and exit.
-d, --debug
print debugging information.
-p PORT
equivalent to '-o port=PORT'
-f do not daemonize, stay in foreground.
-s Single threaded operation.
-C equivalent to '-o compression=yes'
-F ssh_configfile
specifies alternative ssh configuration file
-1 equivalent to '-o ssh_protocol=1'
-o reconnect
automatically reconnect to server if connection is
interrupted. Attempts to access files that were opened
before the reconnection will give errors and need to be
re-opened.
-o delay_connect
Don't immediately connect to server, wait until mountpoint
is first accessed.
-o sshfs_sync
synchronous writes. This will slow things down, but may be
useful in some situations.
-o no_readahead
Only read exactly the data that was requested, instead of
speculatively reading more to anticipate the next read
request.
-o sync_readdir
synchronous readdir. This will slow things down, but may
be useful in some situations.
-o workaround=LIST
Enable the specified workaround. See the Caveats section
below for some additional information. Possible values
are:
rename Emulate overwriting an existing file by deleting
and renaming.
renamexdev
Make rename fail with EXDEV instead of the default
EPERM to allow moving files across remote
filesystems.
truncate
Work around servers that don't support truncate by
coping the whole file, truncating it locally, and
sending it back.
fstat Work around broken servers that don't support
fstat() by using stat instead.
buflimit
Work around OpenSSH "buffer fillup" bug.
createmode
Work around broken servers that produce an error
when passing a non-zero mode to create, by always
passing a mode of 0.
-o idmap=TYPE
How to map remote UID/GIDs to local values. Possible
values are:
none no translation of the ID space (default).
user map the UID/GID of the remote user to UID/GID of
the mounting user.
file translate UIDs/GIDs based upon the contents of
--uidfile and --gidfile.
-o uidfile=FILE
file containing username:uid mappings for -o idmap=file
-o gidfile=FILE
file containing groupname:gid mappings for -o idmap=file
-o nomap=TYPE
with idmap=file, how to handle missing mappings:
ignore don't do any re-mapping
error return an error (default)
-o ssh_command=CMD
execute CMD instead of 'ssh'
-o ssh_protocol=N
ssh protocol to use (default: 2)
-o sftp_server=SERV
path to sftp server or subsystem (default: sftp)
-o directport=PORT
directly connect to PORT bypassing ssh
-o vsock=CID:PORT
directly connect using a vsock to CID:PORT bypassing ssh
-o passive
communicate over stdin and stdout bypassing network.
Useful for mounting local filesystem on the remote side.
An example using dpipe command would be dpipe
/usr/lib/openssh/sftp-server = ssh RemoteHostname sshfs
:/directory/to/be/shared ~/mnt/src -o passive
-o disable_hardlink
With this option set, attempts to call link(2) will fail
with error code ENOSYS.
-o transform_symlinks
transform absolute symlinks on remote side to relative
symlinks. This means that if e.g. on the server side
/foo/bar/com is a symlink to /foo/blub, SSHFS will
transform the link target to ../blub on the client side.
-o follow_symlinks
follow symlinks on the server, i.e. present them as
regular files on the client. If a symlink is dangling
(i.e, the target does not exist) the behavior depends on
the remote server - the entry may appear as a symlink on
the client, or it may appear as a regular file that cannot
be accessed.
-o no_check_root
don't check for existence of 'dir' on server
-o password_stdin
read password from stdin (only for pam_mount!)
-o dir_cache=BOOL
Enables (yes) or disables (no) the SSHFS directory cache.
The directory cache holds the names of directory entries.
Enabling it allows readdir(3) system calls to be processed
without network access.
-o dcache_max_size=N
sets the maximum size of the directory cache.
-o dcache_timeout=N
sets timeout for directory cache in seconds.
-o dcache_{stat,link,dir}_timeout=N
sets separate timeout for {attributes, symlinks, names} in
the directory cache.
-o dcache_clean_interval=N
sets the interval for automatic cleaning of the directory
cache.
-o dcache_min_clean_interval=N
sets the interval for forced cleaning of the directory
cache when full.
-o direct_io
This option disables the use of page cache (file content
cache) in the kernel for this filesystem. This has
several affects:
1. Each read() or write() system call will initiate one or
more read or write operations, data will not be cached
in the kernel.
2. The return value of the read() and write() system calls
will correspond to the return values of the read and
write operations. This is useful for example if the
file size is not known in advance (before reading it).
e.g. /proc filesystem
-o max_conns=N
sets the maximum number of simultaneous SSH connections to
use. Each connection is established with a separate SSH
process. The primary purpose of this feature is to
improve the responsiveness of the file system during large
file transfers. When using more than once connection, the
password_stdin and passive options can not be used, and
the buflimit workaround is not supported.
In addition, SSHFS accepts several options common to all FUSE
file systems. These are described in the mount.fuse manpage (look
for "general", "libfuse specific", and "high-level API" options).
Hardlinks
If the SSH server supports the hardlinks extension, SSHFS will
allow you to create hardlinks. However, hardlinks will always
appear as individual files when seen through an SSHFS mount, i.e.
they will appear to have different inodes and an st_nlink value
of 1.
Rename
Some SSH servers do not support atomically overwriting the
destination when renaming a file. In this case you will get an
error when you attempt to rename a file and the destination
already exists. A workaround is to first remove the destination
file, and then do the rename. SSHFS can do this automatically if
you call it with -o workaround=rename. However, in this case it
is still possible that someone (or something) recreates the
destination file after SSHFS has removed it, but before SSHFS had
the time to rename the old file. In this case, the rename will
still fail.
Permission denied when moving files across remote filesystems
Most SFTP servers return only a generic "failure" when failing to
rename across filesystem boundaries (EXDEV). sshfs normally
converts this generic failure to a permission denied error
(EPERM). If the option -o workaround=renamexdev is given,
generic failures will be considered EXDEV errors which will make
programs like mv(1) attempt to actually move the file after the
failed rename.
SSHFS hangs for no apparent reason
In some cases, attempts to access the SSHFS mountpoint may freeze
if no filesystem activity has occurred for some time. This is
typically caused by the SSH connection being dropped because of
inactivity without SSHFS being informed about that. As a
workaround, you can try to mount with -o ServerAliveInterval=15.
This will force the SSH connection to stay alive even if you have
no activity.
SSHFS hangs after the connection was interrupted
By default, network operations in SSHFS run without timeouts,
mirroring the default behavior of SSH itself. As a consequence,
if the connection to the remote host is interrupted (e.g. because
a network cable was removed), operations on files or directories
under the mountpoint will block until the connection is either
restored or closed altogether (e.g. manually). Applications that
try to access such files or directories will generally appear to
"freeze" when this happens.
If it is acceptable to discard data being read or written, a
quick workaround is to kill the responsible sshfs process, which
will make any blocking operations on the mounted filesystem error
out and thereby "unfreeze" the relevant applications. Note that
force unmounting with fusermount -zu, on the other hand, does not
help in this case and will leave read/write operations in the
blocking state.
For a more automatic solution, one can use the -o
ServerAliveInterval=15 option mentioned above, which will drop
the connection after not receiving a response for 3 * 15 = 45
seconds from the remote host. By also supplying -o reconnect, one
can ensure that the connection is re-established as soon as
possible afterwards. As before, this will naturally lead to loss
of data that was in the process of being read or written at the
time when the connection was interrupted.
To mount an SSHFS filesystem from /etc/fstab, simply use sshfs as
the file system type. (For backwards compatibility, you may also
use fuse.sshfs).
The mount.fuse(8) manpage.
If you need help, please ask on the <‐
[email protected]> mailing list (subscribe at
https://lists.sourceforge.net/lists/listinfo/fuse-sshfs ).
Please report any bugs on the GitHub issue tracker at
https://github.com/libfuse/libfuse/issues .
SSHFS is currently maintained by Nikolaus Rath <‐
[email protected]>, and was created by Miklos Szeredi <‐
[email protected]>.
This man page was originally written by Bartosz Fenski <‐
[email protected]> for the Debian GNU/Linux distribution (but it
may be used by others).
This page is part of the sshfs (SSH Filesystem) project.
Information about the project can be found at
⟨https://github.com/libfuse/sshfs⟩. If you have a bug report for
this manual page, see ⟨https://github.com/libfuse/sshfs/issues⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/libfuse/sshfs.git⟩ on 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2024-02-27.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
SSHFS(1)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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