Columbia Kermit/kermit.zip/newsgroups/misc.20000824-20010305/[e-mail] _Sat Mar 3 20:49:58 2001.msg

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From: Paul Nestler <[e-mail]>
Subject: Re: FTP - loops and parameters for multifile reading
Date: Sat, 03 Mar 2001 20:43:09 -0500
Organization: Posted via Supernews, http://www.supernews.com
Message-ID: <[e-mail]>
To: [e-mail]

Thanks for the reponse.

You have provided an amazing amount of detail.  However, it appears your
example is for the new FTP client you referred to and not for the standard FTP
which comes with AIX 3.2.5 or 4.x.

Am I correct?  Or should your example work with the standard FTP program on
AIX?

Frank da Cruz wrote:

> In article <[e-mail]>,
> Paul Nestler  <[e-mail]> wrote:
> : Does anyone know how to put ftp inside a loop?  Say, a loop that
> : generates a list of filenames to download?
> :
> : Here's the background:
> : I have a problem connection I am dealing with.  When transferring a
> : number of files using mget in ftp, the connection hangs and aborts.  The
> : point at which the ftp session hangs varies from one session to the
> : next, but so far has always allowed me to transfer a few files before it
> : hangs.
> :
> : I looked at the man page for ftp.  The man page discusses a looping
> : feature and the ability to pass a parameter (from the calling script I
> : suppose).  Unfortunately, the man page does not show an example nor does
> : it describe the usage in any useable detail.
> :
> : The man page gave me the notion I should be able to put the ftp inside a
> : loop and pass the name of a file to get from the remote host.  Perhaps
> : there is someway of putting the ftp inside an awk script.
> :
> Let's see how we would do this with the new scriptable C-Kermit FTP
> client.  Let's assume an anonymous login, though it need not be, and that
> the files are to be transferred in binary mode, and that the filenames
> are file1 through file5:
>
>     while true {
>         ftp open somehost.com /anonymous
>         if fail {
>             Can't reach host           ;  Can't make connection
>             sleep 10*60                ;  Wait 10 minutes and try again
>             continue
>         }
>         ftp cd somedirectory
>         if fail {
>             exit 1 Fatal - can't CD to somedirectory on host
>         }
>         while true {
>             ftp mget /binary /recover file1 file2 file3 file4 file5
>             if success goto done        ;  All files downloaded: done.
>             if not \v(ftp_connected) {  ;  Failed - why?
>                 ftp close               ;  Connection closed
>                 break                   ;  Go back and make a new one
>             }
>             ; Connection still open - try MGET again.
>             echo "Download failed - trying again in 20 seconds..."
>             sleep 20
>             continue
>         }
>     }
>     :done
>     ftp bye                             ;  Disconnect from server
>     exit 0                              ;  Exit successfully
>
> This is a very straightforward example, with hardwired host, directory,
> and filenames.  Of course these could also be variables that could be
> resolved in various ways, e.g. from command-line options, with interactive
> prompting, or from a file.
>
> The loop connects to the host, cd's to the desired directory, and requests
> the files in binary mode.  Each step is checked for failure and is retried
> until it succeeds.  Of course you could use a counted loop rather than an
> infinite loop if you wished, and you could use different sleep intervals
> or none at all.
>
> In this example, failure to connect results in a 10-minute pause (assuming
> the host is down or unavailable) and then a loop restart.  You could make
> it do anything else that might be more appropriate.
>
> The magic command is MGET /BINARY /RECOVER <file-list>.  For each file in
> the list:
>
>  . If the file does not exist on the client, it is downloaded; otherwise:
>
>  . If a file of the same name exists on the client, the client requests
>    the host file's size and modification date-time; if the date-time and
>    size are the same, the file is skipped; otherwise:
>
>  . If the date-time is later, the file is downloaded, overwriting the
>    client's copy (which is backed up for safety); otherwise:
>
>  . If the size is greater, the excess part of the host file is downloaded
>    and appended to the client file.
>
> The MGET command is in an inner loop, which retries the MGET command as
> long as it fails and the connection is open.  If MGET fails because the
> connection was closed, the outer loop is continued and a new connection is
> made.  Thus no file is transferred more than once, and if a transfer fails
> in the middle of a file, it is resumed from the point of failure next time
> through the loop.
>
> For more information about the C-Kermit FTP client, see:
>
>   http://www.columbia.edu/kermit/ftpclient.html
>
> And for a tutorial on scripting the new FTP client, see:
>
>   http://www.columbia.edu/kermit/ftpscript.html
>
> The new FTP client is still in prerelease testing but should be perfectly
> usable, and should be formally released soon.   A prebuilt binary for AIX
> 4.3.2 can be downloaded from C-Kermit 7.1 site:
>
>   http://www.columbia.edu/kermit/ck71.html
>
> as well as the source code and binaries for many other platforms.
>
> - Frank