table of contents
other versions
- jessie 1:17.3-dfsg-4+deb8u2
- jessie-backports 1:19.2.1+dfsg-2+deb9u1~bpo8+1
- stretch 1:19.2.1+dfsg-2+deb9u2
- testing 1:21.2.5+dfsg-1
- unstable 1:21.2.6+dfsg-1
- experimental 1:22.0~rc1+dfsg-1
ftp(3erl) | Erlang Module Definition | ftp(3erl) |
NAME¶
ftp - A File Transfer Protocol client.DESCRIPTION¶
This module implements a client for file transfer according to a subset of the File Transfer Protocol (FTP), see RFC 959. As from Inets 4.4.1, 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. An FTP client can be started in two ways. One is using the Inets service framework, the other is to start it directly as a standalone process using function open. For a simple example of an FTP session, see Inets 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 provvided 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 SERVICE START/STOP¶
The FTP client can be started and stopped dynamically in runtime by calling the Inets application API inets:start(ftpc, ServiceConfig), or inets:start(ftpc, ServiceConfig, How), and inets:stop(ftpc, Pid). For details, see inets(3erl). The available configuration options are as follows:- {host, Host}:
Host = string() | ip_address()
- {port, Port}:
Port = integer() > 0
Default is 21.
- {mode, Mode}:
Mode = active | passive
Default is passive.
- {verbose, Verbose}:
Verbose = boolean()
Determines if the FTP communication is to be verbose or not.
Default is false.
- {debug, Debug}:
Debug = trace | debug | disable
Debugging using the dbg toolkit.
Default is disable.
- {ipfamily, IpFamily}:
IpFamily = inet | inet6 | inet6fb4
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}:
Timeout = non_neg_integer()
Connection time-out.
Default is 60000 (milliseconds).
- {dtimeout, DTimeout}:
DTimeout = non_neg_integer() | infinity
Data connect time-out. The time the client waits for the server to connect to
the data socket.
Default is infinity.
- {progress, Progress}:
Progress = ignore | {CBModule, CBFunction, InitProgress}
CBModule = atom(), CBFunction = atom()
InitProgress = term()
Default is ignore.
- *
- 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.
CBModule:CBFunction(InitProgress, File, {file_size, FileSize})
- *
- Every time a chunk of bytes is transferred the following call is made:
CBModule:CBFunction(UserProgressTerm, File, {transfer_size, TransferSize})
- *
- At the end of the file the following call is made to indicate the end of the transfer:
CBModule:CBFunction(UserProgressTerm, File, {transfer_size, 0})
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 ASCCI mode.
The current local working directory (compare lpwd/1) is set to the value
reported by file: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.
DATA TYPES¶
The following type definitions are used by more than one function in the FTP client API: pid() = identifier of an FTP connection string() = list of ASCII characters shortage_reason() = etnospc | epnospc restriction_reason() = epath | efnamena | elogin | enotbinary - all restrictions are not always relevant to all functions common_reason() = econn | eclosed | term() - some explanation of what went wrongEXPORTS¶
account(Pid, Account) -> ok | {error, Reason}
Types:
Pid = pid()
Account = string()
Reason = eacct | common_reason()
Sets the account for an operation, if needed.
append(Pid, LocalFile) ->
Types:
Pid = pid()
LocalFile = RemoteFile = string()
Reason = epath | elogin | etnospc | epnospc | efnamena | common_reason
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.
append_bin(Pid, Bin, RemoteFile) -> ok | {error, Reason}
Types:
Pid = pid()
Bin = binary()()
RemoteFile = string()
Reason = restriction_reason()| shortage_reason() | common_reason()
Transfers the binary Bin to the remote server and appends it to the file
RemoteFile. If the file does not exist, it is created.
append_chunk(Pid, Bin) -> ok | {error, Reason}
Types:
Pid = pid()
Bin = binary()
Reason = echunk | restriction_reason() | common_reason()
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.
append_chunk_start(Pid, File) -> ok | {error, Reason}
Types:
Pid = pid()
File = string()
Reason = restriction_reason() | common_reason()
Starts the transfer of chunks for appending to the file File at the
remote server. If the file does not exist, it is created.
append_chunk_end(Pid) -> ok | {error, Reason}
Types:
Pid = pid()
Reason = echunk | restriction_reason() | shortage_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.
cd(Pid, Dir) -> ok | {error, Reason}
Types:
Pid = pid()
Dir = string()
Reason = restriction_reason() | common_reason()
Changes the working directory at the remote server to Dir.
close(Pid) -> ok
Types:
Pid = pid()
Ends an FTP session, created using function open.
delete(Pid, File) -> ok | {error, Reason}
Types:
Pid = pid()
File = string()
Reason = restriction_reason() | common_reason()
Deletes the file File at the remote server.
formaterror(Tag) -> string()
Types:
Tag = {error, atom()} | atom()
Given an error return value {error, AtomReason}, this function returns a
readable string describing the error.
lcd(Pid, Dir) -> ok | {error, Reason}
Types:
Pid = pid()
Dir = string()
Reason = restriction_reason()
Changes the working directory to Dir for the local client.
lpwd(Pid) -> {ok, Dir}
Types:
Pid = pid()
Returns the current working directory at the local client.
ls(Pid) ->
Types:
Pid = pid()
Pathname = string()
Listing = string()
Reason = restriction_reason() | common_reason()
Returns a list of files in long format.
Pathname can be a directory, a group of files, or a file. The
Pathname 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.
mkdir(Pid, Dir) -> ok | {error, Reason}
Types:
Pid = pid()
Dir = string()
Reason = restriction_reason() | common_reason()
Creates the directory Dir at the remote server.
nlist(Pid) ->
Types:
Pid = pid()
Pathname = string()
Listing = string()
Reason = restriction_reason() | common_reason()
Returns a list of files in short format.
Pathname can be a directory, a group of files, 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.
open(Host) -> {ok, Pid} | {error, Reason}
Types:
Host = string() | ip_address()
Opts = options()
options() = [option()]
option() = start_option() | open_option()
start_option() = {verbose, verbose()} | {debug, debug()}
verbose() = boolean() (default is false)
debug() = disable | debug | trace (default is disable)
open_option() = {ipfamily, ipfamily()} | {port, port()} | {mode, mode()} | {tls,
tls_options()} | {timeout, timeout()} | {dtimeout, dtimeout()} | {progress,
progress()}
ipfamily() = inet | inet6 | inet6fb4 (default is inet)
port() = integer() > 0 (default is 21)
mode() = active | passive (default is passive)
tls_options() = [ ssl:ssloption()]
timeout() = integer() > 0 (default is 60000 milliseconds)
dtimeout() = integer() > 0 | infinity (default is infinity)
pogress() = ignore | {module(), function(), initial_data()} (default is ignore)
module() = atom()
function() = atom()
initial_data() = term()
Reason = ehost | term()
Starts a standalone FTP client process (without the Inets service
framework) and opens a session with the FTP server at Host.
If option {tls, tls_options()} is present, the FTP session is transported
over tls (ftps, see RFC 4217). The list tls_options() can
be empty. The function ssl:connect/3 is used for securing both
the control connection and the data sessions.
A session opened in this way is closed using function close.
pwd(Pid) -> {ok, Dir} | {error, Reason}
Types:
Pid = pid()
Reason = restriction_reason() | common_reason()
Returns the current working directory at the remote server.
recv(Pid, RemoteFile) ->
Types:
Pid = pid()
RemoteFile = LocalFile = string()
Reason = restriction_reason() | common_reason() | file_write_error_reason()
file_write_error_reason() = see file:write/2
Transfers the file RemoteFile from the remote server to the file system
of the local client. If LocalFile is specified, the local file will be
LocalFile, otherwise RemoteFile.
If the file write fails (for example, enospc), the command is aborted and
{error, file_write_error_reason()} is returned. However, the file is
not removed.
recv_bin(Pid, RemoteFile) -> {ok, Bin} | {error, Reason}
Types:
Pid = pid()
Bin = binary()
RemoteFile = string()
Reason = restriction_reason() | common_reason()
Transfers the file RemoteFile from the remote server and receives it as a
binary.
recv_chunk_start(Pid, RemoteFile) -> ok | {error, Reason}
Types:
Pid = pid()
RemoteFile = string()
Reason = restriction_reason() | common_reason()
Starts transfer of the file RemoteFile from the remote server.
recv_chunk(Pid) -> ok | {ok, Bin} | {error, Reason}
Types:
Pid = pid()
Bin = binary()
Reason = restriction_reason() | common_reason()
Receives a chunk of the remote file ( RemoteFile of
recv_chunk_start). The return values have the following meaning:
rename(Pid, Old, New) -> ok | {error, Reason}
- *
- ok = the transfer is complete.
- *
- {ok, Bin} = just another chunk of the file.
- *
- {error, Reason} = transfer failed.
Types:
Pid = pid()
CurrFile = NewFile = string()
Reason = restriction_reason() | common_reason()
Renames Old to New at the remote server.
rmdir(Pid, Dir) -> ok | {error, Reason}
Types:
Pid = pid()
Dir = string()
Reason = restriction_reason() | common_reason()
Removes directory Dir at the remote server.
send(Pid, LocalFile) ->
Types:
Pid = pid()
LocalFile = RemoteFile = string()
Reason = restriction_reason() | common_reason() | shortage_reason()
Transfers the file LocalFile to the remote server. If RemoteFile
is specified, the name of the remote file is set to RemoteFile,
otherwise to LocalFile.
send_bin(Pid, Bin, RemoteFile) -> ok | {error, Reason}
Types:
Pid = pid()
Bin = binary()()
RemoteFile = string()
Reason = restriction_reason() | common_reason() | shortage_reason()
Transfers the binary Bin into the file RemoteFile at the remote
server.
send_chunk(Pid, Bin) -> ok | {error, Reason}
Types:
Pid = pid()
Bin = binary()
Reason = echunk | restriction_reason() | common_reason()
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.
send_chunk_start(Pid, File) -> ok | {error, Reason}
Types:
Pid = pid()
File = string()
Reason = restriction_reason() | common_reason()
Starts transfer of chunks into the file File at the remote server.
send_chunk_end(Pid) -> ok | {error, Reason}
Types:
Pid = pid()
Reason = restriction_reason() | common_reason() | shortage_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.
type(Pid, Type) -> ok | {error, Reason}
Types:
Pid = pid()
Type = ascii | binary
Reason = etype | restriction_reason() | common_reason()
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.
user(Pid, User, Password) -> ok | {error, Reason}
Types:
Pid = pid()
User = Password = string()
Reason = euser | common_reason()
Performs login of User with Password.
user(Pid, User, Password, Account) -> ok | {error, Reason}
Types:
Pid = pid()
User = Password = string()
Reason = euser | common_reason()
Performs login of User with Password to the account specified by
Account.
quote(Pid, Command) -> [FTPLine]
Types:
Pid = pid()
Command = string()
FTPLine = string(
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.
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 or send_chunk_end/1 before a call to send_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.
- 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(3erl) filename(3erl) and J. Postel and J. Reynolds: File Transfer Protocol (RFC 959).inets 6.3.4 | Ericsson AB |