Command Code

Command

Description

USER

User Name

Identifies the user attempting to establish an FTP session.

PASS

Password

Specifies the password for the user given previously by the USER command during login authentication.

ACCT

Account

Specifies an account for an authenticated user during the FTP session. Only used on systems that require this to be separately identified; most select an account automatically based on the name entered in the USER command.

CWD

Change Working Directory

Allows the user to specify a different directory for file transfer during an FTP session.

CDUP

Change To Parent Directory (“Change Directory Up”)

A special case of the CWD command that goes to the directory one level up in the server's directory structure. It is implemented separately to abstract out differences in directory structures between file systems; the user can just use CDUP instead of knowing the specific syntax for navigating up the directory tree on the server.

SMNT

Structure Mount

Allows the user to mount a particular file system for access to different resources.

REIN

Reinitialize

Reinitializes the FTP session, flushing all set parameters and user information. This returns the session to the state when the control connection is just established. It is, in essence, the opposite of the USER command. The next command issued is often USER, to log in a different user.

QUIT

Logout

Terminates the FTP session and closes the control connection.

Note that the naming of this command “Logout” was unfortunate; the REIN command is really most similar to a conventional “logout” command, as it terminates a logged-in user and allows another user to log in. In contrast, the QUIT command shuts down the entire session.

Command Code

Command

Description

PORT

Data Port

Used to tell the FTP server that the client wants to accept an active data connection on a specific port number.

PASV

Passive

Requests that the FTP server allow the User-DTP to initiate passive data connections.

TYPE

Representation Type

Specifies for the file to be transferred the data type (ASCII, EBCDIC, Image or Local), and optionally the format control (Non Print, Telnet or Carriage Control).

STRU

File Structure

Specifies the data structure for the file (File, Record or Page).

MODE

Transfer Mode

Specifies the transmission mode to be used (Stream, Block or Compressed).

Command Code

Command

Description

RETR

Retrieve

Tells the server to send the user a file.

STOR

Store

Sends a file to the server.

STOU

Store Unique

Like STOR, but instructs the server to make sure the file has a unique name in the current directory. This is used to prevent overwriting a file that may already exist with the same name. The server replies back with the name used for the file.

APPE

Append (with Create)

Like STOR, but if a file with the name specified already exists, the data being sent is appended to it instead of replacing it.

ALLO

Allocate

An optional command used to reserve storage on the server before a file is sent.

REST

Restart

Restarts a file transfer at a particular server marker. Used only for Block or Compressed transfer modes.

RNFR

Rename From

Specifies the old name of a file to be renamed. See the RNTO command just below.

RNTO

Rename To

Specifies the new name of a file to be renamed. Used with the RNFR command.

ABOR

Abort

Tells the server to abort the last FTP command and/or the current data transfer.

DELE

Delete

Deletes a specified file on the server.

RMD

Remove Directory

Deletes a directory on the server.

MKD

Make Directory

Creates a directory.

PWD

Print Working Directory

Displays the current server working directory for the FTP session; shows the user “where they are” in the server's file system.

LIST

List

Requests a list of the contents of the current directory from the server, including both names and other information. Similar in concept to the “DIR” command in DOS/Windows or the “ls” command in UNIX.

NLST

Name List

Like LIST, but returns only the names in a directory.

SITE

Site Parameters

Used to implement site-specific functions.

SYST

System

Requests that the server send to the client information about the server's operating system.

STAT

Status

Prompts the server to send an indication of the status of a file or the transfer currently in progress.

HELP

Help

Asks the server for any help information that might be useful in allowing the user to determine how the server should be used.

NOOP

No Operation

Does nothing, other than prompting the server to send an “OK” response to verify that the control channel is alive.