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(This article assumes that you are familar with Perl
When uploading files from a local PC to a remote FTP-server, I ran into the
problem of having to upload a lot of files, where only a few actually changed.
So I decided to compare the timestamps of the local files with those of the
remote files. Theoretically a file needs to be uploaded only if
- the local
modification date is newer than the remote modification date or
- the remote
file doesn't exists at all.
In practice, the problem is that the FTP-Server has another timebase (e.g.
its clock is some seconds ahed or behind the local clock), so the comparison
The solution presented in this article handles this by storing the
modification dates of the files to upload in a local database and does
the comparison with these timestamps.
In a nutshell the "algorithm" works , for each file to upload, like
- Does an entry for the file exist in the database?
- If no, upload it, create new recordset for this file, storing its
path and modification date.
- If yes, compare the actually modification date of the file with the
stored modification date in the database.
- If actual modification date is newer than the stored one, upload
the file, store its modification date in the database.
- If actual modification date is older than the stored one, do
As a drawback, the very first time the script is started, the database is
empty, and therefore it once uploads all files, even if they would
already exists on the remote FTP-server.
Starting from the second time, the script is executed, it works as described
You must have installed the Windows version of Perl from ActiveState.
I always use the latest version, which is ActivePerl
5.6 as of writing this article.
In addition, I'm using some modules that are not in the standard distribution
of Perl. These modules can be obtained from CPAN at www.cpan.org.
The following extra modules need to be installed:
Each module contains a readme file which explains how to install.
When Perl and all modules are installed, you need to configure the script.
The following values must be configured:
||The address (IP or name) of the remote FTP-server
||The subdirectory on the remote FTP-server. Use no slash at the
||The username (user-ID) of the account to log on to the FTP-server
||The password of the account to log on to the FTP-server
||An array of directories to upload. Each given directory is recursively
processed (i.e. subdirectories are processed, too).
||An array of substring to match to exclude files or directories.
For each found file (i.e. its complete path), a substring-match is
executed, and then only if no item is found, this file or directory
||The ADO connection string to connect to the database. You can use here
any valid expression, e.g. an OLE-DB string or an ODBC string.
||"Provider=Microsoft.Jet.OLEDB.4.0;Persist Security Info=False;Data
||The username of the account to connect to the database. Usually this
field is empty.
||The password of the account to connect to the database. Usually this
field is empty.
When you configured everything, simple execute the script by double-clicking
it in the explorer or by typing "perl upload.pl" at the command
The script writes outpout to stdout, as well as to a logfile called
If you have any suggestions, found errors or want to comment on that article
or script, please write a comment to at the end of this article and I
will answer it.
Please keep in mind that I'm doing Perl for only some few month right now. So
there are probably a lot of "no really beautiful" code-fragments in my
script. So if you have any constructive comments regarding my coding style or
how the way I use Perl, please tell me!