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Reference Manual
Version 2.1.7

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# ssh_sftp

### MODULE

ssh_sftp

### MODULE SUMMARY

SFTP client.

### DESCRIPTION

This module implements an SFTP (SSH FTP) 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 and/or abstractions to indicate the intended use of the data type:

ssh_connection_ref() - opaque to the user returned by ssh:connect/3

timeout() = infinity | integer() - in milliseconds.

### TIMEOUTS

If the request functions for the SFTP channel return {error, timeout} it does not guarantee that the request did not reach the server and was not performed, it only means that we did not receive an answer from the server within the time that was expected.

### EXPORTS

start_channel(ConnectionRef) ->
start_channel(ConnectionRef, Options) ->
start_channel(Host, Options) ->
start_channel(Host, Port, Options) -> {ok, Pid} | {ok, Pid, ConnectionRef} | {error, Reason}

Types:

Host = string()
ConnectionRef = ssh_connection_ref()
Port = integer()
Options = [{Option, Value}]
Reason = term()

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 should be used as input to all other API functions in this module.

Options are:

{timeout, timeout()}

  The timeout is passed to the ssh_channel start function, and defaults to infinity.

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 connetion. Use ssh:close/1 to close it.

read_file(ChannelPid, File) ->
read_file(ChannelPid, File, Timeout) -> {ok, Data} | {error, Reason}

Types:

ChannelPid = pid()
File = string()
Data = binary()
Timeout = timeout()
Reason = term()

Reads a file from the server, and returns the data in a binary, like file:read_file/1.

write_file(ChannelPid, File, Iolist) ->
write_file(ChannelPid, File, Iolist, Timeout) -> ok | {error, Reason}

Types:

ChannelPid = pid()
File = string()
Iolist = iolist()
Timeout = timeout()
Reason = term()

Writes a file to the server, like file:write_file/2. The file is created if it does not exist or is owerwritten if it does.

list_dir(ChannelPid, Path) ->
list_dir(ChannelPid, Path, Timeout) -> {ok, Filenames} | {error, Reason}

Types:

ChannelPid = pid()
Path = string()
Filenames = [Filename]
Filename = string()
Timeout = timeout()
Reason = term()

Lists the given directory on the server, returning the filenames as a list of strings.

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()
Reason = term()

Opens a file on the server, and returns a handle that 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()
Reason = term()

Opens a handle to a directory on the server, the handle can be used for reading directory contents.

close(ChannelPid, Handle) ->
close(ChannelPid, Handle, Timeout) -> ok | {error, Reason}

Types:

ChannelPid = pid()
Handle = term()
Timeout = timeout()
Reason = term()

Closes a handle to an open file or directory on the server.

read(ChannelPid, Handle, Len) ->
read(ChannelPid, Handle, Len, Timeout) -> {ok, Data} | eof | {error, Error}
pread(ChannelPid, Handle, Position, Len) ->
pread(ChannelPid, Handle, Position, Len, Timeout) -> {ok, Data} | eof | {error, Error}

Types:

ChannelPid = pid()
Handle = term()
Position = integer()
Len = integer()
Timeout = timeout()
Data = string() | binary()
Reason = term()

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 will be read and returned. If no bytes are read, eof is returned.

The pread function reads from a specified position, combining the position and read functions.

aread(ChannelPid, Handle, Len) -> {async, N} | {error, Error}
apread(ChannelPid, Handle, Position, Len) -> {async, N} | {error, Error}

Types:

ChannelPid = pid()
Handle = term()
Position = integer()
Len = integer()
N = term()
Reason = 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}, or eof, or {error, Error}.

The apread function reads from a specified position, combining the position and aread functions.

write(ChannelPid, Handle, Data) ->
write(ChannelPid, Handle, Data, Timeout) -> ok | {error, Error}
pwrite(ChannelPid, Handle, Position, Data) -> ok
pwrite(ChannelPid, Handle, Position, Data, Timeout) -> ok | {error, Error}

Types:

ChannelPid = pid()
Handle = term()
Position = integer()
Data = iolist()
Timeout = timeout()
Reason = term()

Writesdata to the file referenced by Handle. The file should be opened with write or append flag. Returns ok if successful or S{error, Reason} otherwise.

Typical error reasons are:

ebadf

  The file is not opened for writing.

enospc

  There is a no space left on the device.

awrite(ChannelPid, Handle, Data) -> ok | {error, Reason}
apwrite(ChannelPid, Handle, Position, Data) -> ok | {error, Reason}

Types:

ChannelPid = pid()
Handle = term()
Position = integer()
Len = integer()
Data = binary()
Timeout = timeout()
Reason = term()

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, Error}.

The apwrite writes on a specified position, combining the position and awrite operations.

position(ChannelPid, Handle, Location) ->
position(ChannelPid, Handle, Location, Timeout) -> {ok, NewPosition | {error, Error}

Types:

ChannelPid = pid()
Handle = term()
Location = Offset | {bof, Offset} | {cur, Offset} | {eof, Offset} | bof | cur | eof
Offset = integer()
Timeout = timeout()
NewPosition = integer()
Reason = term()

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 above with Offset 0.

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()
Reason = term()

Returns a file_info record from the file specified by Name or Handle, like file:read_file_info/2.

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()
Reason = term()

Returns a file_info record from the symbolic link specified by Name or Handle, like file:read_link_info/2.

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()
Reason = term()

Writes file information from a file_info record to the file specified by Name, like file:write_file_info.

read_link(ChannelPid, Name) ->
read_link(ChannelPid, Name, Timeout) -> {ok, Target} | {error, Reason}

Types:

ChannelPid = pid()
Name = string()
Target = string()
Reason = term()

Reads the link target from the symbolic link specified by name, like file:read_link/1.

make_symlink(ChannelPid, Name, Target) ->
make_symlink(ChannelPid, Name, Target, Timeout) -> ok | {error, Reason}

Types:

ChannelPid = pid()
Name = string()
Target = string()
Reason = term()

Creates a symbolic link pointing to Target with the name Name, like file:make_symlink/2.

rename(ChannelPid, OldName, NewName) ->
rename(ChannelPid, OldName, NewName, Timeout) -> ok | {error, Reason}

Types:

ChannelPid = pid()
OldName = string()
NewName = string()
Timeout = timeout()
Reason = term()

Renames a file named OldName, and gives it the name NewName, like file:rename/2

delete(ChannelPid, Name) ->
delete(ChannelPid, Name, Timeout) -> ok | {error, Reason}

Types:

ChannelPid = pid()
Name = string()
Timeout = timeout()
Reason = term()

Deletes the file specified by Name, like file:delete/1

make_dir(ChannelPid, Name) ->
make_dir(ChannelPid, Name, Timeout) -> ok | {error, Reason}

Types:

ChannelPid = pid()
Name = string()
Timeout = timeout()
Reason = term()

Creates a directory specified by Name. Name should be a full path to a new directory. The directory can only be created in an existing directory.

del_dir(ChannelPid, Name) ->
del_dir(ChannelPid, Name, Timeout) -> ok | {error, Reason}

Types:

ChannelPid = pid()
Name = string()
Timeout = timeout()
Reason = term()

Deletes a directory specified by Name. Note that the directory must be empty before it can be successfully deleted