write FTP URLs in file name text fields or when using the command line application?

According to the specification of URL formats (RFC 1738 ), an FTP URL is of the form
ftp://<user>:<password>@< host>:<port>/< url-path>

If you wish to access a FTP server with SSL support, the URL must start with "ftps" instead of "ftp".

Some or all of the parts "<user>:<password>@", ":<password>", ":<port>", and "/<url-path>" may be excluded.

The different components obey the following rules:

user
An optional user name.
password
An optional password. If present, it follows the user name separated from it by a colon.

The user name (and password), if present, are followed by a commercial at-sign "@". Within the user and password field, any ":", "@", or "/" must be encoded.

An empty user name or password is different than no user name or password; there is no way to specify a password without specifying a user name. E.g., <URL:ftp://@host.com/> has an empty user name and no password, <URL:ftp://host.com/> has no user name, while <URL:ftp://foo:@host.com/> has a user name of "foo" and an empty password.

host
The fully qualified domain name of a network host, or its IP address as a set of four decimal digit groups separated by ".". Fully qualified domain names take the form as described in Section 3.5 of RFC 1034 [13] and Section 2.1 of RFC 1123 [5]: a sequence of domain labels separated by ".", each domain label starting and ending with an alphanumerical character and possibly also containing "-" characters. The rightmost domain label will never start with a digit, though, which syntactically distinguishes all domain names from the IP addresses.
port
The port number to connect to. If the port is omitted, the colon is as well.
url-path
The rest of the locator supplies the details of how the specified resource can be accessed. Note that the "/" between the host (or port) and the url-path is NOT part of the url-path.

The url-path of a FTP URL has the following syntax:
<cwd1>/<cwd2>/.../< cwdN>/<name>
Where <cwd1> through <cwdN> and <name> are (possibly encoded) strings. The <cwdx> and <name> parts may be empty. The whole url-path may be omitted, including the "/" delimiting it from the prefix containing user, password, host, and port.

See also