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How to Resume Partial File Transfers

I work primarily with UNIX and Linux machines and scp is my main choice to transfer files with. It is both convenient, short and secure.

Example:

scp localfile user@remotecomputer:/path/to/target/dir

Recently I was transferring an 8GB file and due to a network issue, the transfer was interrupted at nearly 40%.

I have learned over the years that there is often little which can be done to prevent such interruptions. I know that many people go to great lengths to find Broadband which is reliable, but sometimes disruptions simply cannot be avoided. Of course, this can be both frustrating and time-consuming, but there is a quick fix. Although such disruptions can’t be prevented, there is a fast and easy way to resume them. Resuming has relatively few system requirements, and can save a lot of time and hassle when transferring large files.

I found a solution at joen.dk ,which uses rsync to resume the transfer:

rsync --partial --progress --rsh=ssh host:remote_file local_file

Now we can improve this slightly by shortening the above command. We can substitute –rsh=ssh with -e ssh, and use -P instead of –partial –progress. Also, you can add user@host if you need to specify a different remote shell user:

rsync -P -e ssh user@host:remote_file local_file

This above example will work with any file that was partially transfered. How the transfer was started does not really matter. It could be through scp, nc or even ftp. After you execute the above command it will take rsync a little time to verify the previously downloaded part before it continues with the rest. Be patient, depending on your network speed rsync could take some time to go through what you have already transfered. Of course this is much faster than if you were to start the download all over again and it shows you the progress in percentages.

Keep in mind that there have to be a couple of requirements in place in order to resume the file transfer with rsync:

1. You should have remote shell access.
2. The remote machine should have rsync installed. Since rsync is by default on most Linux distributions that generally should not be an issue.

When a Linux User Buys Apple

I just came upon two articles by Thomas Driemeyer. The author seems to be very sincere in his attempt to describe his experiences in switching from Linux to Apple (and subsequently back) and his good sense of humor makes the reading pleasant and amusing:

When a Linux user buys Apple’s Mac mini

When an Apple Mac mini user gets disenchanted

Has Apple become like Mirosoft? Or may be even worse?

I love Apple!

I cannot live without my iPod, much less without my iPhone! The “I am a Mac, I am a PC” commercials on TV are so adorable… Sometimes I rewind my DVR just to see one of those commercials again. In these moments I tell myself “Show that evil empire Microsoft how things are done!”.

But then… I must have been brain dead for a while! You see, what got me is that I have always been for a free market and fair competition. And what Microsoft was doing was not right. No two ways about it. Apple was the company that materialized those feelings and stood up to Microsoft. Naturally, I (like many others) fell for it and blindly screamed “Go Apple!”.

It turns out that I have supported a company that became worse than the one it had set out to defy.

Apple said that if you want to have an iPod, you can only use it with iTunes and if you want to buy music for it… guess what?… you need iTunes for that as well. Same applies to the iPhone with the only difference that you have to be an AT&T customer. Oh yeah… and all these songs you might have bought from Apple, you can’t put on any other mp3 player but on an iPod, unless you remove the DRM protection.

On the computer front things do not look much more different. Mac OS X can legally run only on officially approved Apple hardware and vise versa. If you like the OS, well your only chance is to drop some major cash for the hardware as well. This goes over and beyond what Microsoft has ever attempted to do. After all you can run Windows on anything you feel like.

I am a huge believer in FOSS and Apple has shaped to be the absolute opposite of this philosophy. Even though their OS is built on top of FreeBSD and NetBSD, and they have ported a number of Linux applications to Mac OS X, they have not contrubuted back to the community at all. They even officially announced that iTunes will not be released for Linux. I would like to think that the only reason for this is because they know that Linux users are not going to tollerate DRM content anyway.