View Source ftp (ftp v1.2.2)
A File Transfer Protocol client.
This module implements a client for file transfer according to a subset of the File Transfer Protocol (FTP), see RFC 959.
The FTP client always tries to use passive FTP mode and only resort to active FTP mode if this fails. This default behavior can be changed by start option mode.
For a simple example of an FTP session, see FTP User's Guide.
In addition to the ordinary functions for receiving and sending files (see
recv/2
, recv/3
, send/2
, and
send/3
) there are functions for receiving remote files as binaries
(see recv_bin/2
) and for sending binaries to be stored as
remote files (see send_bin/3
).
A set of functions is provided for sending and receiving contiguous parts of a
file to be stored in a remote file. For send, see
send_chunk_start/2
, send_chunk/2
,
and send_chunk_end/1
. For receive, see
recv_chunk_start/2
and recv_chunk/
).
The return values of the following functions depend much on the implementation
of the FTP server at the remote host. In particular, the results from ls
and
nlist
varies. Often real errors are not reported as errors by ls
, even if,
for example, a file or directory does not exist. nlist
is usually more strict,
but some implementations have the peculiar behaviour of responding with an error
if the request is a listing of the contents of a directory that exists but is
empty.
FTP CLIENT START/STOP
The FTP client can be started and stopped dynamically in runtime by calling the
ftp
application API ftp:open(Host, Options)
and ftp:close(Client)
.
Data Types
The following type definitions are used by more than one function in the FTP client API:
pid/0
= identifier of an FTP connection
string/0
= list of ASCII characters
ERRORS
The possible error reasons and the corresponding diagnostic strings returned by
formaterror/1
are as follows:
echunk
- Synchronization error during chunk sending according to one of the following:- A call is made to
send_chunk/2
orsend_chunk_end/1
before a call tosend_chunk_start/2
. - A call has been made to another transfer function during chunk sending, that
is, before a call to
send_chunk_end/1
.
- A call is made to
eclosed
- The session is closed.econn
- Connection to the remote server is prematurely closed.ehost
- Host is not found, FTP server is not found, or connection is rejected by FTP server.elogin
- User is not logged in.enotbinary
- Term is not a binary.epath
- No such file or directory, or directory already exists, or permission denied.etype
- No such type.euser
- Invalid username or password.etnospc
- Insufficient storage space in system [452].epnospc
- Exceeded storage allocation (for current directory or dataset) [552].efnamena
- Filename not allowed [553].
SEE ALSO
file
filename
and J. Postel and J. Reynolds: File Transfer Protocol
(RFC 959).
Summary
Functions
Sets the account for an operation, if needed.
Equivalent to append/3
Transfers the file LocalFile
to the remote server. If RemoteFile
is
specified, the name of the remote file that the file is appended to is set to
RemoteFile
, otherwise to LocalFile
. If the file does not exists, it is
created.
Transfers the binary Bin
to the remote server and appends it to the file
RemoteFile
. If the file does not exist, it is created.
Transfers the chunk Bin
to the remote server, which appends it to the file
specified in the call to append_chunk_start/2
.
Stops transfer of chunks for appending to the remote server. The file at the
remote server, specified in the call to
append_chunk_start/2
, is closed by the server.
Starts the transfer of chunks for appending to the file RemoteFile
at the
remote server. If the file does not exist, it is created.
Changes the working directory at the remote server to Dir
.
Ends an FTP session, created using function open.
Deletes the file File
at the remote server.
Given an error return value {error, AtomReason}
, this function returns a
readable string describing the error.
Changes the working directory to Dir
for the local client.
Returns the current working directory at the local client.
Returns a list of files in long format.
Creates the directory Dir
at the remote server.
Equivalent to nlist/2
Returns a list of files in short format.
Equivalent to open/2
Starts a FTP client process and opens a session with the FTP server at Host
.
Returns the current working directory at the remote server.
Note
The telnet end of line characters, from the FTP protocol definition, CRLF, for example, "\\r\\n" has been removed.
Equivalent to recv/3
Transfers the file RemoteFileName
from the remote server to the file system of
the local client. If LocalFileName
is specified, the local file will be
LocalFileName
, otherwise RemoteFileName
.
Transfers the file RemoteFile
from the remote server and receives it as a
binary.
Receives a chunk of the remote file (RemoteFile
of recv_chunk_start
). The
return values have the following meaning
Starts transfer of the file RemoteFile
from the remote server.
Renames Old
to New
at the remote server.
Removes directory Dir
at the remote server.
Equivalent to send/3
Transfers the file LocalFileName
to the remote server. If RemoteFileName
is
specified, the name of the remote file is set to RemoteFileName
, otherwise to
LocalFileName
.
Transfers the binary Bin
into the file RemoteFile
at the remote server.
Transfers the chunk Bin
to the remote server, which writes it into the file
specified in the call to send_chunk_start/2
.
Stops transfer of chunks to the remote server. The file at the remote server,
specified in the call to send_chunk_start/2
is closed
by the server.
Starts transfer of chunks into the file RemoteFile
at the remote server.
Sets the file transfer type to ascii
or binary
. When an FTP session is
opened, the default transfer type of the server is used, most often ascii
,
which is default according to RFC 959.
Performs login of User
with Pass
.
Performs login of User
with Pass
to the account specified by Account
.
Functions
Sets the account for an operation, if needed.
Equivalent to append/3
-spec append(Pid :: pid(), LocalFileName :: string(), RemoteFileName :: string()) -> ok | {error, Reason :: term()}.
Transfers the file LocalFile
to the remote server. If RemoteFile
is
specified, the name of the remote file that the file is appended to is set to
RemoteFile
, otherwise to LocalFile
. If the file does not exists, it is
created.
-spec append_bin(Pid :: pid(), Bin :: binary(), RemoteFile :: string()) -> ok | {error, Reason :: term()}.
Transfers the binary Bin
to the remote server and appends it to the file
RemoteFile
. If the file does not exist, it is created.
Transfers the chunk Bin
to the remote server, which appends it to the file
specified in the call to append_chunk_start/2
.
For some errors, for example, file system full, it is necessary to call
append_chunk_end
to get the proper reason.
Stops transfer of chunks for appending to the remote server. The file at the
remote server, specified in the call to
append_chunk_start/2
, is closed by the server.
Starts the transfer of chunks for appending to the file RemoteFile
at the
remote server. If the file does not exist, it is created.
Changes the working directory at the remote server to Dir
.
-spec close(Pid :: pid()) -> ok.
Ends an FTP session, created using function open.
Deletes the file File
at the remote server.
Given an error return value {error, AtomReason}
, this function returns a
readable string describing the error.
Changes the working directory to Dir
for the local client.
Returns the current working directory at the local client.
Equivalent to ls/2
Returns a list of files in long format.
Dir
can be a directory or a file. The Dir
string can contain wildcards.
ls/1
implies the current remote directory of the user.
The format of Listing
depends on the operating system. On UNIX, it is
typically produced from the output of the ls -l
shell command.
Creates the directory Dir
at the remote server.
Equivalent to nlist/2
-spec nlist(Pid :: pid(), Pathname :: string()) -> {ok, Listing :: string()} | {error, Reason :: term()}.
Returns a list of files in short format.
Pathname
can be a directory or a file. The Pathname
string can contain
wildcards.
nlist/1
implies the current remote directory of the user.
The format of Listing
is a stream of filenames where each filename is
separated by <CRLF> or <NL>. Contrary to function ls
, the purpose of nlist
is to enable a program to process filename information automatically.
-spec open(Host :: string() | inet:ip_address()) -> {ok, Pid :: pid()} | {error, Reason :: term()}.
Equivalent to open/2
-spec open(Host :: string() | inet:ip_address(), Opts) -> {ok, Pid :: pid()} | {error, Reason :: term()} when Opts :: [Opt], Opt :: StartOption | OpenOption, StartOption :: {verbose, Verbose} | {debug, Debug}, Verbose :: boolean(), Debug :: disable | debug | trace, OpenOption :: {ipfamily, IpFamily} | {port, Port :: port()} | {mode, Mode} | {tls, TLSOptions :: [ssl:tls_option()]} | {tls_sec_method, TLSSecMethod :: ftps | ftpes} | {tls_ctrl_session_reuse, TLSSessionReuse :: boolean()} | {timeout, Timeout :: timeout()} | {dtimeout, DTimeout :: timeout()} | {progress, Progress} | {sock_ctrl, SocketCtrls} | {sock_data_act, [SocketControl]} | {sock_data_pass, [SocketControl]}, SocketCtrls :: [SocketControl], IpFamily :: inet | inet6 | inet6fb4, Mode :: active | passive, Module :: atom(), Function :: atom(), InitialData :: term(), Progress :: ignore | {Module, Function, InitialData}, SocketControl :: gen_tcp:option().
Starts a FTP client process and opens a session with the FTP server at Host
.
A session opened in this way is closed using function close/1
.
The available configuration options are as follows:
{port, Port} - Default is
0
which aliases to21
or990
when used with{tls_sec_method,ftps}
).{verbose, Verbose} - Determines if the FTP communication is to be verbose or not.
Default is
false
.{debug, Debug} - Debugging using the dbg toolkit.
Default is
disable
.{ipfamily, IpFamily} - With
inet6fb4
the client behaves as before, that is, tries to use IPv6, and only if that does not work it uses IPv4).Default is
inet
(IPv4).{timeout, Timeout} - Connection time-out.
Default is
60000
(milliseconds).{dtimeout, DTimeout} - Data connect time-out. The time the client waits for the server to connect to the data socket.
Default is
infinity
.{tls, TLSOptions} - The FTP session is transported over
tls
(ftps
, see RFC 4217). The listTLSOptions
can be empty. The functionssl:connect/3
is used for securing both the control connection and the data sessions.{tls_sec_method, TLSSecMethod} - When set to
ftps
will connect immediately with SSL instead of upgrading with STARTTLS. This suboption is ignored unless the suboptiontls
is also set.Default is
ftpes
{tls_ctrl_session_reuse, boolean()} - When set to
true
the client will re-use the TLS session from the control channel on the data channel as enforced by many FTP servers as (proposed and implemented first by vsftpd).Default is
false
.{sock_ctrl, SocketCtrls :: [SocketControl :: gen_tcp:option()]} - Passes options from
SocketCtrls
down to the underlying transport layer (tcp).gen_tcp:option/0
except foripv6_v6only
,active
,packet
,mode
,packet_size
andheader
.Default value is
SocketCtrls = []
.{sock_data_act, [SocketControl]} - Passes options from
[SocketControl]
down to the underlying transport layer (tcp).sock_data_act
uses the value ofsock_ctrl
as default value.{sock_data_pass, [SocketControl]} - Passes options from
[SocketControl]
down to the underlying transport layer (tcp).sock_data_pass
uses the value ofsock_ctrl
as default value.{progress, Progress} - Progress =
ignore | {Module, Function, InitialData}
Module = atom()
,Function = atom()
InitialData = term()
Default is
ignore
.Option
progress
is intended to be used by applications that want to create some type of progress report, such as a progress bar in a GUI. Default for the progress option isignore
, that is, the option is not used. When the progress option is specified, the following happens whenftp:send/[3,4]
orftp:recv/[3,4]
are called:Before a file is transferred, the following call is made to indicate the start of the file transfer and how large the file is. The return value of the callback function is to be a new value for the
UserProgressTerm
that will be used as input the next time the callback function is called.Module:Function(InitialData, File, {file_size, FileSize})
Every time a chunk of bytes is transferred the following call is made:
Module:Function(UserProgressTerm, File, {transfer_size, TransferSize})
At the end of the file the following call is made to indicate the end of the transfer:
Module:Function(UserProgressTerm, File, {transfer_size, 0})
The callback function is to be defined as follows:
Module:Function(UserProgressTerm, File, Size) -> UserProgressTerm
UserProgressTerm = term()
File = string()
Size = {transfer_size, integer()} | {file_size, integer()} | {file_size, unknown}
For remote files,
ftp
cannot determine the file size in a platform independent way. In this case the size becomesunknown
and it is left to the application to determine the size.Note
The callback is made by a middleman process, hence the file transfer is not affected by the code in the progress callback function. If the callback crashes, this is detected by the FTP connection process, which then prints an info-report and goes on as if the progress option was set to
ignore
.The file transfer type is set to the default of the FTP server when the session is opened. This is usually ASCII mode.
The current local working directory (compare
lpwd/1
) is set to the value reported byfile:get_cwd/1
, the wanted local directory.The return value
Pid
is used as a reference to the newly created FTP client in all other functions, and they are to be called by the process that created the connection. The FTP client process monitors the process that created it and terminates if that process terminates.
Returns the current working directory at the remote server.
Note
The telnet end of line characters, from the FTP protocol definition, CRLF, for example, "\\r\\n" has been removed.
Sends an arbitrary FTP command and returns verbatim a list of the lines sent back by the FTP server. This function is intended to give application accesses to FTP commands that are server-specific or that cannot be provided by this FTP client.
Note
FTP commands requiring a data connection cannot be successfully issued with this function.
Equivalent to recv/3
-spec recv(Pid :: pid(), RemoteFileName :: string(), LocalFileName :: string()) -> ok | {error, Reason :: term()}.
Transfers the file RemoteFileName
from the remote server to the file system of
the local client. If LocalFileName
is specified, the local file will be
LocalFileName
, otherwise RemoteFileName
.
If the file write fails, the command is aborted and {error, term()}
is
returned. However, the file is not removed.
-spec recv_bin(Pid :: pid(), RemoteFile :: string()) -> {ok, Bin :: binary()} | {error, Reason :: term()}.
Transfers the file RemoteFile
from the remote server and receives it as a
binary.
Receives a chunk of the remote file (RemoteFile
of recv_chunk_start
). The
return values have the following meaning:
ok
= the transfer is complete.{ok, Bin}
= just another chunk of the file.{error, Reason}
= transfer failed.
Starts transfer of the file RemoteFile
from the remote server.
Renames Old
to New
at the remote server.
Removes directory Dir
at the remote server.
Equivalent to send/3
-spec send(Pid :: pid(), LocalFileName :: string(), RemoteFileName :: string()) -> ok | {error, Reason :: term()}.
Transfers the file LocalFileName
to the remote server. If RemoteFileName
is
specified, the name of the remote file is set to RemoteFileName
, otherwise to
LocalFileName
.
-spec send_bin(Pid :: pid(), Bin :: binary(), RemoteFile :: string()) -> ok | {error, Reason :: term()}.
Transfers the binary Bin
into the file RemoteFile
at the remote server.
Transfers the chunk Bin
to the remote server, which writes it into the file
specified in the call to send_chunk_start/2
.
For some errors, for example, file system full, it is necessary to to call
send_chunk_end
to get the proper reason.
Stops transfer of chunks to the remote server. The file at the remote server,
specified in the call to send_chunk_start/2
is closed
by the server.
Starts transfer of chunks into the file RemoteFile
at the remote server.
Sets the file transfer type to ascii
or binary
. When an FTP session is
opened, the default transfer type of the server is used, most often ascii
,
which is default according to RFC 959.
Performs login of User
with Pass
.
-spec user(Pid :: pid(), User :: string(), Pass :: string(), Account :: string()) -> ok | {error, Reason :: term()}.
Performs login of User
with Pass
to the account specified by Account
.