Error downloading .txt or .nc files through the ftp link

By using the following function;

>> ftpobj = ftp('ftp://nrt.cmems-du.eu/Core/INSITU_GLO_NRT_OBSERVATIONS_013_030/glo_multiparameter_nrt/index_monthly.txt',username,password,'System','UNIX')

I am encountering with the error message, I reaaly appreciate any help.

Error using connect (line 18)

Could not open a connection to "ftp", port "NaN".

Error in ftp (line 75)

connect(h)

Thanks

[Geoff Hayes]

Farshid - please see ftp host input parameter to get an idea of how the host should be constructed. You seem to be passing a link to a file rather than the name of the FTP server (with or without the port).

Answer 1

[Andrew Janke]

Geoff is right. You're passing a URL to ftp(), when it only accepts host names. You need to do the directory navigation and file selection in a separate step once you're connected. Try this:

remote_dir = 'Core/INSITU_GLO_NRT_OBSERVATIONS_013_030/glo_multiparameter_nrt';
remote_file = 'index_monthly.txt';
f = ftp('nrt.cmems-du.eu',username,password);
cd(f, remote_dir)
mget(f, remote_file)

[Farshid Daryabor]

Dear Andrew, thanks but how can I fix the error arise from the function "mget"

Error using ftp/mget (line 109)

FTP error: 500.

109 error(message('MATLAB:ftp:FTPError',replyCode))

[Andrew Janke]

FTP Error 500 is a "syntax error: command unrecognized". I don't know why it would be doing that; sorry.

Try doing the download manually with ncftp or another command-line ftp client to make sure things are working with other tools, too.

[Andrew Janke]

Any chance you could share a login to this ftp site so we could run your code and try to reproduce the error?

[Farshid Daryabor]

It's really an easy way when you want to analysis over a thousand files. I could manage it for "http" without having any problem, I want to solve it for "ftp" too.

remote_dir = 'Core/INSITU_GLO_NRT_OBSERVATIONS_013_030/glo_multiparameter_nrt';

remote_file = 'index_monthly.txt';

f = ftp('host','username','password');

cd(f, remote_dir)

mget(f, remote_file)

[Andrew Janke]

What version of Matlab are you running? Your example code fails for me in Matlab R2016b and R2017b, but works in R2018b and R2019b. (On macOS.) (Oddly, I looked at the source for ftp/mget and I don't really see what it's doing different between R2017b and R2018b. And I'm pretty sure it's using the same version of Apache Commons FTP.) You could upgrade to Matlab R2018b and maybe it'll work. Or you could try my alternative jl.net.ftp.FtpClient class: https://github.com/apjanke/janklab/blob/master/Mcode/classes/%2Bjl/%2Bnet/%2Bftp/FtpClient.m.

[Farshid Daryabor]

could you show me example to run?

f = jl.net.ftp.FtpClient('Core/INSITU_GLO_NRT_OBSERVATIONS_013_030/glo_multiparameter_nrt')

Undefined variable "jl" or class "jl.net.ftp.FtpClient".

[Geoff Hayes]

Farshid - I modified your above comment to remove the host, username, and password from the code. I strongly recommend that you don't post such information on a public forum.

Answer 2

[Farshid Daryabor]

what do you mean? You mean to add "Ftp Client.m" to the path and run it?

[Andrew Janke]

If you want to try my FtpClient out, download the whole Janklab library and add that to the path. Instructions are at https://github.com/apjanke/janklab#installation-and-use.

Might be easier for you to just upgrade Matlab. What version are you running? Do you have a current license?

[Farshid Daryabor]

2016b, unfortunately my center not able to upgrade it.

[Andrew Janke]

Ah. You're out of luck then; Janklab requires R2017b or later.

Here's the example code for future reference in case you're able to upgrade to R2017b or later some time. Or you could just take my FtpClient.m code (and the other classes in the +jl/+net/+ftp package) and modify them to run in R2016b outside Janklab; they're not using that much code from the rest of the library.

addpath ~/local/repos/janklab/Mcode/toplevel/
init_janklab
remote_dir = 'Core/INSITU_GLO_NRT_OBSERVATIONS_013_030/glo_multiparameter_nrt';
remote_file = 'index_monthly.txt';

f = jl.net.ftp.FtpClient('nrt.cmems-du.eu');
f.username = my_username;
f.password = my_password;
f.connect;
f.cd(remote_dir);
f.mget(remote_file);

[Andrew Janke]

You know what, my FtpClient isn't working with that server either. It's also getting error 500 reply codes. I don't know what's going on there. I'll try turning on some protocol level logging to see what's going on.

[Andrew Janke]

Aha: You need to use Passive Mode. (Which is the whole reason I wrote that FtpClient in the first place.)

f = jl.net.ftp.FtpClient('nrt.cmems-du.eu', [], my_username, my_password);
f.connect;
f.pasv;
f.cd(remote_dir);
f.mget(remote_file);

[Farshid Daryabor]

Dear Andrew,

I'm really sorry for the delay in feedback. I actually added "class" and "toplevel" packages to the path. However, I did find some imbalance errors in "FtpClient" which I cleaned some of, but in the list below some errors have confused me to clear. Could you please tell me how I can fix it, thanks in advance.

% Remote host to connect to

host (1,1) string = string(missing)

% Port for the command port

port (1,1) double = NaN

% Username to log in as. Defaults to 'anonymous'.

username (1,1) string = 'anonymous'

% Password to provide. Defaults to your email address from Matlab's

% Internet prefs

password string = repmat('', [0 0])

% Account to use in addition to username and password. May be empty to

% indicate "no account"

account string = repmat('', [0 0])

end

properties(Dependent)