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NAME
ssh_sftp - SFTP client.
DESCRIPTION
This module implements an SSH FTP (SFTP) client. SFTP is a secure, encrypted file transfer service
available for SSH.
DATA TYPES
Type definitions that are used more than once in this module, or abstractions to indicate the intended
use of the data type, or both:
reason():
= atom() A description of the reason why an operation failed.
The value is formed from the sftp error codes in the protocol-level responses as defined in draft-
ietf-secsh-filexfer-13.txt section 9.1.
The codes are named as SSH_FX_* which are transformed into lowercase of the star-part. E.g. the error
code SSH_FX_NO_SUCH_FILE will cause the reason() to be no_such_file.
ssh_connection_ref() =:
opaque() - as returned by ssh:connect/3
timeout():
= infinity | integer() in milliseconds. Default infinity.
TIME-OUTS
If the request functions for the SFTP channel return {error, timeout}, no answer was received from the
server within the expected time.
The request may have reached the server and may have been performed. However, no answer was received from
the server within the expected time.
EXPORTS
apread(ChannelPid, Handle, Position, Len) -> {async, N} | {error, reason()}
Types:
ChannelPid = pid()
Handle = term()
Position = integer()
Len = integer()
N = term()
The apread/4 function reads from a specified position, combining the position/3 and aread/3
functions.
apwrite(ChannelPid, Handle, Position, Data) -> {async, N} | {error, reason()}
Types:
ChannelPid = pid()
Handle = term()
Position = integer()
Len = integer()
Data = binary()
Timeout = timeout()
N = term()
The apwrite/4 function writes to a specified position, combining the position/3 and awrite/3
functions.
aread(ChannelPid, Handle, Len) -> {async, N} | {error, reason()}
Types:
ChannelPid = pid()
Handle = term()
Position = integer()
Len = integer()
N = term()
Reads from an open file, without waiting for the result. If the handle is valid, the function
returns {async, N}, where N is a term guaranteed to be unique between calls of aread. The actual
data is sent as a message to the calling process. This message has the form {async_reply, N,
Result}, where Result is the result from the read, either {ok, Data}, eof, or {error, reason()}.
awrite(ChannelPid, Handle, Data) -> {async, N} | {error, reason()}
Types:
ChannelPid = pid()
Handle = term()
Position = integer()
Len = integer()
Data = binary()
Timeout = timeout()
Writes to an open file, without waiting for the result. If the handle is valid, the function
returns {async, N}, where N is a term guaranteed to be unique between calls of awrite. The result
of the write operation is sent as a message to the calling process. This message has the form
{async_reply, N, Result}, where Result is the result from the write, either ok, or {error,
reason()}.
close(ChannelPid, Handle) ->
close(ChannelPid, Handle, Timeout) -> ok | {error, reason()}
Types:
ChannelPid = pid()
Handle = term()
Timeout = timeout()
Closes a handle to an open file or directory on the server.
delete(ChannelPid, Name) ->
delete(ChannelPid, Name, Timeout) -> ok | {error, reason()}
Types:
ChannelPid = pid()
Name = string()
Timeout = timeout()
Deletes the file specified by Name.
del_dir(ChannelPid, Name) ->
del_dir(ChannelPid, Name, Timeout) -> ok | {error, reason()}
Types:
ChannelPid = pid()
Name = string()
Timeout = timeout()
Deletes a directory specified by Name. The directory must be empty before it can be successfully
deleted.
list_dir(ChannelPid, Path) ->
list_dir(ChannelPid, Path, Timeout) -> {ok, Filenames} | {error, reason()}
Types:
ChannelPid = pid()
Path = string()
Filenames = [Filename]
Filename = string()
Timeout = timeout()
Lists the given directory on the server, returning the filenames as a list of strings.
make_dir(ChannelPid, Name) ->
make_dir(ChannelPid, Name, Timeout) -> ok | {error, reason()}
Types:
ChannelPid = pid()
Name = string()
Timeout = timeout()
Creates a directory specified by Name. Name must be a full path to a new directory. The directory
can only be created in an existing directory.
make_symlink(ChannelPid, Name, Target) ->
make_symlink(ChannelPid, Name, Target, Timeout) -> ok | {error, reason()}
Types:
ChannelPid = pid()
Name = string()
Target = string()
Creates a symbolic link pointing to Target with the name Name.
open(ChannelPid, File, Mode) ->
open(ChannelPid, File, Mode, Timeout) -> {ok, Handle} | {error, reason()}
Types:
ChannelPid = pid()
File = string()
Mode = [Modeflag]
Modeflag = read | write | creat | trunc | append | binary
Timeout = timeout()
Handle = term()
Opens a file on the server and returns a handle, which can be used for reading or writing.
opendir(ChannelPid, Path) ->
opendir(ChannelPid, Path, Timeout) -> {ok, Handle} | {error, reason()}
Types:
ChannelPid = pid()
Path = string()
Timeout = timeout()
Opens a handle to a directory on the server. The handle can be used for reading directory
contents.
open_tar(ChannelPid, Path, Mode) ->
open_tar(ChannelPid, Path, Mode, Timeout) -> {ok, Handle} | {error, reason()}
Types:
ChannelPid = pid()
Path = string()
Mode = [read] | [write] | [read,EncryptOpt] | [write,DecryptOpt]
EncryptOpt = {crypto,{InitFun,EncryptFun,CloseFun}}
DecryptOpt = {crypto,{InitFun,DecryptFun}}
InitFun = (fun() -> {ok,CryptoState}) | (fun() -> {ok,CryptoState,ChunkSize})
CryptoState = any()
ChunkSize = undefined | pos_integer()
EncryptFun = (fun(PlainBin,CryptoState) -> EncryptResult)
EncryptResult = {ok,EncryptedBin,CryptoState} | {ok,EncryptedBin,CryptoState,ChunkSize}
PlainBin = binary()
EncryptedBin = binary()
DecryptFun = (fun(EncryptedBin,CryptoState) -> DecryptResult)
DecryptResult = {ok,PlainBin,CryptoState} | {ok,PlainBin,CryptoState,ChunkSize}
CloseFun = (fun(PlainBin,CryptoState) -> {ok,EncryptedBin})
Timeout = timeout()
Opens a handle to a tar file on the server, associated with ChannelPid. The handle can be used for
remote tar creation and extraction, as defined by the erl_tar:init/3 function.
For code exampel see Section SFTP Client with TAR Compression and Encryption in the ssh Users
Guide.
The crypto mode option is applied to the generated stream of bytes prior to sending them to the
SFTP server. This is intended for encryption but can be used for other purposes.
The InitFun is applied once prior to any other crypto operation. The returned CryptoState is then
folded into repeated applications of the EncryptFun or DecryptFun. The binary returned from those
funs are sent further to the remote SFTP server. Finally, if doing encryption, the CloseFun is
applied to the last piece of data. The CloseFun is responsible for padding (if needed) and
encryption of that last piece.
The ChunkSize defines the size of the PlainBins that EncodeFun is applied to. If the ChunkSize is
undefined, the size of the PlainBins varies, because this is intended for stream crypto, whereas a
fixed ChunkSize is intended for block crypto. ChunkSizes can be changed in the return from the
EncryptFun or DecryptFun. The value can be changed between pos_integer() and undefined.
position(ChannelPid, Handle, Location) ->
position(ChannelPid, Handle, Location, Timeout) -> {ok, NewPosition | {error, reason()}
Types:
ChannelPid = pid()
Handle = term()
Location = Offset | {bof, Offset} | {cur, Offset} | {eof, Offset} | bof | cur | eof
Offset = integer()
Timeout = timeout()
NewPosition = integer()
Sets the file position of the file referenced by Handle. Returns {ok, NewPosition} (as an absolute
offset) if successful, otherwise {error, reason()}. Location is one of the following:
Offset:
The same as {bof, Offset}.
{bof, Offset}:
Absolute offset.
{cur, Offset}:
Offset from the current position.
{eof, Offset}:
Offset from the end of file.
bof | cur | eof:
The same as eariler with Offset 0, that is, {bof, 0} | {cur, 0} | {eof, 0}.
pread(ChannelPid, Handle, Position, Len) ->
pread(ChannelPid, Handle, Position, Len, Timeout) -> {ok, Data} | eof | {error, reason()}
Types:
ChannelPid = pid()
Handle = term()
Position = integer()
Len = integer()
Timeout = timeout()
Data = string() | binary()
The pread/3,4 function reads from a specified position, combining the position/3 and read/3,4
functions.
pwrite(ChannelPid, Handle, Position, Data) -> ok
pwrite(ChannelPid, Handle, Position, Data, Timeout) -> ok | {error, reason()}
Types:
ChannelPid = pid()
Handle = term()
Position = integer()
Data = iolist()
Timeout = timeout()
The pwrite/3,4 function writes to a specified position, combining the position/3 and write/3,4
functions.
read(ChannelPid, Handle, Len) ->
read(ChannelPid, Handle, Len, Timeout) -> {ok, Data} | eof | {error, reason()}
Types:
ChannelPid = pid()
Handle = term()
Position = integer()
Len = integer()
Timeout = timeout()
Data = string() | binary()
Reads Len bytes from the file referenced by Handle. Returns {ok, Data}, eof, or {error, reason()}.
If the file is opened with binary, Data is a binary, otherwise it is a string.
If the file is read past eof, only the remaining bytes are read and returned. If no bytes are
read, eof is returned.
read_file(ChannelPid, File) ->
read_file(ChannelPid, File, Timeout) -> {ok, Data} | {error, reason()}
Types:
ChannelPid = pid()
File = string()
Data = binary()
Timeout = timeout()
Reads a file from the server, and returns the data in a binary.
read_file_info(ChannelPid, Name) ->
read_file_info(ChannelPid, Name, Timeout) -> {ok, FileInfo} | {error, reason()}
Types:
ChannelPid = pid()
Name = string()
Handle = term()
Timeout = timeout()
FileInfo = record()
Returns a file_info record from the file specified by Name or Handle. See file:read_file_info/2
for information about the record.
read_link(ChannelPid, Name) ->
read_link(ChannelPid, Name, Timeout) -> {ok, Target} | {error, reason()}
Types:
ChannelPid = pid()
Name = string()
Target = string()
Reads the link target from the symbolic link specified by name.
read_link_info(ChannelPid, Name) -> {ok, FileInfo} | {error, reason()}
read_link_info(ChannelPid, Name, Timeout) -> {ok, FileInfo} | {error, reason()}
Types:
ChannelPid = pid()
Name = string()
Handle = term()
Timeout = timeout()
FileInfo = record()
Returns a file_info record from the symbolic link specified by Name or Handle. See
file:read_link_info/2 for information about the record.
rename(ChannelPid, OldName, NewName) ->
rename(ChannelPid, OldName, NewName, Timeout) -> ok | {error, reason()}
Types:
ChannelPid = pid()
OldName = string()
NewName = string()
Timeout = timeout()
Renames a file named OldName and gives it the name NewName.
start_channel(ConnectionRef) ->
start_channel(ConnectionRef, Options) -> {ok, Pid} | {error, reason()|term()}
start_channel(Host, Options) ->
start_channel(Host, Port, Options) -> {ok, Pid, ConnectionRef} | {error, reason()|term()}
start_channel(TcpSocket) ->
start_channel(TcpSocket, Options) -> {ok, Pid, ConnectionRef} | {error, reason()|term()}
Types:
Host = string()
ConnectionRef = ssh_connection_ref()
Port = integer()
TcpSocket = port()
The socket is supposed to be from gen_tcp:connect or gen_tcp:accept with option
{active,false}
Options = [{Option, Value}]
If no connection reference is provided, a connection is set up, and the new connection is
returned. An SSH channel process is started to handle the communication with the SFTP server. The
returned pid for this process is to be used as input to all other API functions in this module.
Options:
{timeout, timeout()}:
There are two ways to set a timeout for the underlying ssh connection:
* If the connection timeout option connect_timeout is set, that value is used also for the
negotiation timeout and this option (timeout) is ignored.
* Otherwise, this option (timeout) is used as the negotiation timeout only and there is no
connection timeout set
The value defaults to infinity.
{sftp_vsn, integer()}:
Desired SFTP protocol version. The actual version is the minimum of the desired version and
the maximum supported versions by the SFTP server.
All other options are directly passed to ssh:connect/3 or ignored if a connection is already
provided.
stop_channel(ChannelPid) -> ok
Types:
ChannelPid = pid()
Stops an SFTP channel. Does not close the SSH connection. Use ssh:close/1 to close it.
write(ChannelPid, Handle, Data) ->
write(ChannelPid, Handle, Data, Timeout) -> ok | {error, reason()}
Types:
ChannelPid = pid()
Handle = term()
Position = integer()
Data = iolist()
Timeout = timeout()
Writes data to the file referenced by Handle. The file is to be opened with write or append flag.
Returns ok if successful or {error, reason()} otherwise.
write_file(ChannelPid, File, Iolist) ->
write_file(ChannelPid, File, Iolist, Timeout) -> ok | {error, reason()}
Types:
ChannelPid = pid()
File = string()
Iolist = iolist()
Timeout = timeout()
Writes a file to the server. The file is created if it does not exist but overwritten if it
exists.
write_file_info(ChannelPid, Name, Info) ->
write_file_info(ChannelPid, Name, Info, Timeout) -> ok | {error, reason()}
Types:
ChannelPid = pid()
Name = string()
Info = record()
Timeout = timeout()
Writes file information from a file_info record to the file specified by Name. See
file:write_file_info/[2,3] for information about the record.