Category: apple

(A post every 10 months. I hope that does not annoy you :) It will not take long to read, anyway. )

Transmission is a great BitTorrent client. It is full of features (look at the site!), including bandwidth control, and runs on every platform (Linux and Mac :P).
You can choose global upload and download speeds, or shape single torrents among those you are working with.
At home I have a 10mbit connection to the Internet so I rarely limit the torrents, but most of the time when I do it is to reserve a small quantity of bandwidth for Internet browsing while I wait, or to play online.

Transmission is a bit rigid regarding the possible speeds: the only possible values (for both upload and download) expressed in kilobytes/sec are 5, 10, 20, 30, 40, 50, 75, 100, 150, 200, 250, 500, 750, 1000, 1500, 2000. My home network chokes around 600. I could set for 500k, but where’s the fun?

So:

• head to https://trac.transmissionbt.com/wiki/Building and read thoroughly [the part specifying that you need to have XCode installed, for example]
• learn that “Building the project on Mac requires the source to be retrieved from SVN. Pre-packaged source code will not compile.“
• download the SVN code (uhm, yes. I also have pkgsrc installed):
  svn co svn://svn.transmissionbt.com/Transmission/trunk Transmission
  in my case the version number was 2.11 1133-something.
• run a “dry” compile run — this will guarantee that the code is not broken before you start tinkering with it or that you have some local issue (my first time doing actually something with XCode. Easier than I thought, the source has an XCode project file)
• find the relevant source files (grep was my friend). In the end I only modified Controller.m and TorrentTableView.m: find the line
  const NSInteger speedLimitActionValue[] = { 5, 10, 20, 30, 40, 50, 75,
100, 150, 200, 250, 500, 750, 1000, 1500, 2000, -1 };
  and modify it to match the speeds you want to be able to use. You can add or remove values as you like as long as the syntax is right.
• compile it again and run it. :)

If I were a programmer, I’d have implemented something that would allow the user to choose the speed as he liked — but this fits my needs.

At first I did not notice, but emptying the trash took ages, even “not securely”.
Well, being the geek I am I did a quick dtruss on the Locum process, which spit out a huge list of write_nocancel syscalls. So, it seems it was actually writing stuff over the files I asked him to delete, even if I never asked him to (I just did a right click on the Trash icon, and selected “Empty Trash”). WTF?

Well, I learned (thanks Google) that Snow Leopard does a secure erase of the trash by default. Annoying.
And that I did not realize that until now. Embarassing.

So, this can be solved at least in two ways:

The GUI one
Go into Finder preferences, Advanced, and uncheck “Empty Trash securely”

or

the CLI one
Go into ~/Library/Preferences, convert the Finder preferences to xml (it’s binary by default)
plutil -convert xml1 com.apple.finder.plist
and change the stanza

<key>EmptyTrashSecurely</key>
<true/>
to
<key>EmptyTrashSecurely</key>
<false/>

Like it happens on Windows, when you decide to delete something OSX simply moves that file or directory to “the Trash”, which is just a hidden directory on the volume you’re deleting from. Then, you right click on the Trash icon and select “Empty trash”.
This action pops up a small window like this:

I grew tired of asking myself what OSX was deleting (the operation can take a while, especially when — as I often do — you’re doing a secure erase) so this ugly one-liner, run as root, will give you the file the OS is working on:


ps auxw | grep -i locum | grep -v grep | awk '{print $2}' | xargs lsof -p | grep -i Trash | awk '{print $9}'


It will output something like this:
/Volumes/FAT80GB/.Trashes/502/xcode3210a432.dmg

You can wrap that command inside the usual while/sleep loop if you want something that keeps you updated on what is going on — or make it an alias for your favourite shell.