我看了看，sshfs --help没有提到密钥文件。我的计算机上有多个 pub/priv 密钥对（用于不同的服务器），我想指定要使用的密钥。我该怎么做？
usage: sshfs [user@]host:[dir] mountpoint [options]
general options:
-o opt,[opt...] mount options
-h --help print help
-V --version print version
SSHFS options:
-p PORT equivalent to '-o port=PORT'
-C equivalent to '-o compression=yes'
-F ssh_configfile specifies alternative ssh configuration file
-1 equivalent to '-o ssh_protocol=1'
-o reconnect reconnect to server
-o delay_connect delay connection to server
-o sshfs_sync synchronous writes
-o no_readahead synchronous reads (no speculative readahead)
-o sshfs_debug print some debugging information
-o cache=BOOL enable caching {yes,no} (default: yes)
-o cache_timeout=N sets timeout for caches in seconds (default: 20)
-o cache_X_timeout=N sets timeout for {stat,dir,link} cache
-o workaround=LIST colon separated list of workarounds
none no workarounds enabled
all all workarounds enabled
[no]rename fix renaming to existing file (default: off)
[no]nodelaysrv set nodelay tcp flag in sshd (default: off)
[no]truncate fix truncate for old servers (default: off)
[no]buflimit fix buffer fillup bug in server (default: on)
-o idmap=TYPE user/group ID mapping, possible types are:
none no translation of the ID space (default)
user only translate UID of connecting user
-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 transform_symlinks transform absolute symlinks to relative
-o follow_symlinks follow symlinks on the server
-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 SSHOPT=VAL ssh options (see man ssh_config)
FUSE options:
-d -o debug enable debug output (implies -f)
-f foreground operation
-s disable multi-threaded operation
-o allow_other allow access to other users
-o allow_root allow access to root
-o nonempty allow mounts over non-empty file/dir
-o default_permissions enable permission checking by kernel
-o fsname=NAME set filesystem name
-o subtype=NAME set filesystem type
-o large_read issue large read requests (2.4 only)
-o max_read=N set maximum size of read requests
-o hard_remove immediate removal (don't hide files)
-o use_ino let filesystem set inode numbers
-o readdir_ino try to fill in d_ino in readdir
-o direct_io use direct I/O
-o kernel_cache cache files in kernel
-o [no]auto_cache enable caching based on modification times (off)
-o umask=M set file permissions (octal)
-o uid=N set file owner
-o gid=N set file group
-o entry_timeout=T cache timeout for names (1.0s)
-o negative_timeout=T cache timeout for deleted names (0.0s)
-o attr_timeout=T cache timeout for attributes (1.0s)
-o ac_attr_timeout=T auto cache timeout for attributes (attr_timeout)
-o intr allow requests to be interrupted
-o intr_signal=NUM signal to send on interrupt (10)
-o modules=M1[:M2...] names of modules to push onto filesystem stack
-o max_write=N set maximum size of write requests
-o max_readahead=N set maximum readahead
-o async_read perform reads asynchronously (default)
-o sync_read perform reads synchronously
-o atomic_o_trunc enable atomic open+truncate support
-o big_writes enable larger than 4kB writes
-o no_remote_lock disable remote file locking
Module options:
[subdir]
-o subdir=DIR prepend this directory to all paths (mandatory)
-o [no]rellinks transform absolute symlinks to relative
[iconv]
-o from_code=CHARSET original encoding of file names (default: UTF-8)
-o to_code=CHARSET new encoding of the file names (default: UTF-8)