Scott Redding talks about the 2018 Aprilia MotoGP team.

It's been a long while since I've come across something that I felt needed to be preserved but this is it.
And it hits a little close to home.
Not from my experiences with my MotoGP team, obviously, not even is it related to my own motorcycle racing.
But I know that kind of frustration. The frustration of knowing you can pull something off if only circumstances were slightly different. The frustration of having all your achievements flushed away because you're part of a team and that team is fucking things up and people aren't acknowledging that. Shit like this wouldn't be necessary if we would all be willing to put the same effort into being accountable for stupid shit we do as covering our own asses. The world caters to mediocrity.
It takes shitloads of courage to burn bridges like this and I applaud him for it.

Scott Redding is highly critical of Aprilia after a dismal showing in Austria, says, “you cannot make a piece of shit, shine. And that's what I'm trying to do.”

After finishing a lowly 20th in Sunday’s MotoGP outing in Austria, Scott Redding has provided an astonishingly frank take on a dismal showing, describing Sunday’s race as “heartbreaking” and saying the weekend was “hell from the beginning.”

The Englishman was highly critical of Aprilia, listing a number of mechanical issues he encountered throughout free practice, qualifying and on race day. “In a team of this level it should not be happening,” he said on Sunday afternoon. “And it is happening.” 

Having placed a competitive second in a soaking wet FP2 session, Redding said the showing came as a timely reminder of his talents, and only served to highlight the RS-GP’s deficiencies in the dry. “You cannot make a piece of shit, shine,” was the takeaway line from an impassioned debrief. “And that's what I'm trying to do.” 

Redding was not only unable to explain why he finished well outside the points. The reason he took the chequered flag 21 seconds back of team-mate Aleix Espargaro, when he had provided the Catalan with competition in recent outings, was also something of a mystery. 

“The [wet] conditions bring the machines closer,” said Redding. “I can see my potential. I can be fast. And it just reminded me of how good I can actually be. I just accepted it this year, I've never had a wet session. But then this weekend was like, 'yeah, well you can mix with the best guys in the world when the level comes a bit lower with the machinery'. Then it dries again and you're out in the field again. 

“It's been hard. It's been a hard weekend and to be honest to have a race like that is heart-breaking because I try all the time and it doesn't get easier. Why can I go to Assen and battle with my team-mate, in Brno I can battle with my team-mate - yes I crashed - then I come here and I can't even fucking be in the same situation. 

“Every time I go on the bike, every fucking day is different. There's always a problem with something. Every weekend there is a problem. And I've tried to accept it and I've tried to just deal with it, but honestly it's a bit of disaster at the moment. And I'm not happy. This weekend was a reality check for me. Riding around there, it hurts. 

“So now I have to go to Silverstone, the next race. I need to smile in front of everyone and say I'm going to do a good performance and it's all bullshit. Because you can't do anything. You cannot make a piece of shit, shine. And that's what I'm trying to do. 

“I know it sounds harsh and I shouldn't say it, but that's what it is. You're trying to make something average be better. I just hope when we go testing next week at Misano, that we can find something, we have a new engine… what is it going to bring? 

“It's something that I've asked for five races ago, if not more. I hope that it's better. I do hope. But if it continues like this I don’t know what mindset I'm going to be in because this is not what I go racing for. I don't do it.” 

It didn’t end there. Asked whether these repeated mechanical issues had been ongoing for some time, and he went again, describing the current situation as “a bit of a joke."
“The guys are trying but it's just a bit of a joke. There are so many things that I'm just not even allowed to say, not against me, but in a team of this level should not be happening. And it's happening. And I accept it. 

“But I come here. I can be fast here and I've made good results in the past, I like the track, it suits my style. I thought I'd come here and have a good chance of making a good enough result for us. And it was hell from the beginning. 

“And then we find out yesterday night there was a problem with the sensor, this and this and this. The suspension is reading different to what it's doing. Fucking hell. This is MotoGP, a full factory team. Why is this happening? 

“I've had problems with the electronics all the weekend, cannot get it to work. So what hope do I have to make a result here? I can't. And that's the thing that is making it hard at the moment.” 

Not even the possibility of testing at Misano next weekend offered up optimism. Aprilia’s management of the supposed shakedown was also “a fucking joke,” in the 25-year old’s eyes, as the factory had originally intended to spend three days on the Adriatic coast. Now he and Espargaro are only booked in for one. 

”To be honest even that's a fucking joke. We were supposed to do three days. Then it was two days. Then something was not organised enough and now we have one day. Things like that you know. We need that test time, we need those things. But it's a joke. 

“So the important thing, we have the engine, OK. Something big to try. We have one day, we can focus on that and I hope that it brings something. That's all I do. Just hope.”
Does he feel clear-the-air talks with Aprilia management and technicians could be of benefit before the all-important home race at Silverstone in two week’s time? 

“I've tried,” he said. “I've tried already from round one. And I was in a bad place earlier this year and I said to everyone that I'm not happy, I need to move on forget it and let it be. And I was doing that, but then when you realise how good you can be and you can't do it again and it's holding you back and it's holding you back. That's what's so frustrating. 

“I had the same in qualifying yesterday. Go in FP4 with the medium, I go in the qualifying with the soft and I go slower. And I have problems that I haven't had all weekend. I go in the race and I have problems again I haven't had all weekend. Why? Is the bike that bad that it changed from three degrees. I don't know. But you can never find the rhythm. 

“I'm honestly better off doing FP1, warm-up and the race. The rest of it just forget it and I would do the same result. Because it doesn’t matter what you do.
“I had a problem with the suspension so it was too soft. 'Cannot stop the bike, cannot stop the bike', it was all I complained about. Oh yeah, it was the problem. Okay, we change the fork spring. Okay, I can stop, and the lap time is the same. Because you run into another problem. 

“Because all you are doing is covering. You're not fixing something and moving on. I had not a tyre problem, got to Sachsenring and now tyre wear is really high. Where did that come from? OK, at the Sachsenring we can expect it. Brno we struggled, here we struggled. Seven laps… it's frustrating because you want to do it, you work to do it and you can't do it.”

-Neil Morrison, crash.net, 12 Aug 2018 (link to the original article) 

Wurmd move from Google code to Github

Just in case anyone besides me would actually be using it: I've moved wurmd from Google Code, which has been deprecated for quite some time, to Github. https://github.com/timdingo/wurmd.

On ecryptfs and ssh public key authentication.

I'm using an Ubuntu (not by choice, mind you) box to compile stuff on, which I've set up with ecryptfs to encrypt my user's home directory.
It's a headless box so most of the stuff I do on it is over SSH and I've been really annoyed to learn ecryptfs, by default,  auto-unmounts the user's home directly every time the SSH session disconnects.
Why, you ask? Because it breaks public key authentication aka 'passwordless login'.
Turns out ecryptfs, by default, needs the user's login password to decrypt the volume, which it then mounts so all is good as long as one's using a password based login procedure.
Anyways: a reasonable workaround (as there's no fixing this design issue), as long as the box doesn't shutdown too often, that is, is to not allow the volume to unmount every time the working session is closed:

• Supply the password once over SSH, which auto-mounts the volume
• Remove the ~/.ecryptfs/auto-umount file
• Done

On Debian's init process

Are you tired of badly written, complex, buggy and generally shitty init systems on Debian based systems?
Do you wonder what certain Debian developers have been smoking lately?
Do you think upstart, systemd and the likes need to stay the fuck away from your otherwise pretty stable Debian systems and do you long for the simpler SysV days?
Yeh, me too.

apt-get install sysvinit systemd-

or

apt-get install sysvinit upstart-

takes care of it.
That's all.

Bancontact mobile application with a Belgian Keytrade account

It took some time to get it working; if the 'activation' step in the mobile application keeps failing, do this:
Log into the Keytrade web site and go to 'Cards' -> 'Card Security' -> 'Activate Card for Online Payments'.
That's it.

Screenshot because it's fancy:

Unsetting a trap

Quick one: catching a trap in bash is fairly easy with bash' trap command (search for 'trap \[' in bash' man page) but how to clear a set one?
It's in the man page, of course, but who reads those, right? I'm betting the answer is bound to be found on some blog through Google in 0.76 seconds flat ;)

"If arg is absent (and there is a single sigspec) or -, each specified signal is reset to its original disposition (the value it had upon entrance to the shell)."

So it turns out it's fairly simple and this demonstrates it:

root@mgmtsrv:~# cat test.sh
#!/bin/bash
trap 'echo TRAPPED!; break' SIGINT
while [ True ]; do
        sleep 1
done
echo 'end of script'
exit 0
root@mgmtsrv:~# ./test.sh
^CTRAPPED!
end of script
root@mgmtsrv:~#

Now, let's unset the trap:

root@mgmtsrv:~# cat test.sh
#!/bin/bash
trap 'echo TRAPPED!; break' SIGINT
while [ True ]; do
        sleep 1
done
trap - SIGINT
while [ True ]; do
        sleep 1
done
echo 'end of script'
exit 0
root@mgmtsrv:~# ./test.sh
^CTRAPPED!
^C
root@mgmtsrv:~#

So, in short: the 'trap - SIGINT' line clears the set trap :)

On loopback device creation

I was having some problems with loop back device creating & almost immediately detaching; it seems sometimes a kernel thread holds on to the device and the detach fails.
I decided to have a look what's going on so I created a script which automates the creation, attaching and detaching of loopback devices:

# ./test.sh

Creating sparse 4TB file: Done
----START----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
----NEXT PASS----
Loopback devices currently in use:
/dev/loop0
Checking for free loopback device: /dev/loop1
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
----NEXT PASS----
Loopback devices currently in use:
/dev/loop0
/dev/loop1
Checking for free loopback device: /dev/loop2
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
----NEXT PASS----
Loopback devices currently in use:
/dev/loop0
/dev/loop1
/dev/loop2
Checking for free loopback device: /dev/loop3
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
----NEXT PASS----
Loopback devices currently in use:
/dev/loop0
/dev/loop1
/dev/loop2
/dev/loop3
Checking for free loopback device: /dev/loop4
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
----NEXT PASS----
Loopback devices currently in use:
/dev/loop0
/dev/loop1
/dev/loop2
/dev/loop3
/dev/loop4
Checking for free loopback device: /dev/loop5
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
----NEXT PASS----
Loopback devices currently in use:
/dev/loop0
/dev/loop1
/dev/loop2
/dev/loop3
/dev/loop4
/dev/loop5
Checking for free loopback device: /dev/loop6
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
----NEXT PASS----
Loopback devices currently in use:
/dev/loop0
/dev/loop1
/dev/loop2
/dev/loop3
/dev/loop4
/dev/loop5
/dev/loop6
Checking for free loopback device: /dev/loop7
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
----NEXT PASS----
Loopback devices currently in use:
/dev/loop0
/dev/loop1
/dev/loop2
/dev/loop3
/dev/loop4
/dev/loop5
/dev/loop6
/dev/loop7
Checking for free loopback device: losetup: could not find any free loop device
Exiting, couldn't find any free device any more.

So if done fast enough the pool quickly gets depleted as giving back (detaching) the device fails. A second or so later it might work, though. But let's test how much time exactly is needed to free the device? I modified the script to keep trying to detach/free the loopback device and see what happens:

Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 4 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 2 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 6 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 1 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 3 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 3 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.

Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 2 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 3 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 2 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 4 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 4 tries.
----NEXT PASS----
Loopback devices currently in use:

Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 1 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 5 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 10 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 2 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 4 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 4 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 3 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
Loopback device broken down after 0 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 4 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 3 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 2 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
Loopback device broken down after 0 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 1 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 3 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 2 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 1 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 2 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 1 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
Loopback device broken down after 1 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: ^C

So it varies. The device might get released instantaneously, but that doesn't happen too often, or it might take 10 consecutive tries. Let's see if allowing half a second's worth of pause in between creating and detaching fix the problem,

# ./test.sh
Creating sparse 4TB file: Done
----START----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0.5 seconds.
Breaking down loopback device:
Loopback device broken down after 0 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0.5 seconds.
Breaking down loopback device:
Loopback device broken down after 0 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0.5 seconds.
Breaking down loopback device:
Loopback device broken down after 0 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0.5 seconds.
Breaking down loopback device:
Loopback device broken down after 0 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0.5 seconds.

^C

It does, but what's holding on to the device exactly? I modified the script again to look up the did in the process table. This takes time of course, so the detaching phase took less tries to complete:

# ./test.sh
Creating sparse 4TB file: Done
----START----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
root     25417  0.0  0.0      0     0 ?        S<   13:25   0:00 [loop0]
Loopback device broken down after 1 tries.
----NEXT PASS----
Loopback devices currently in use:
Checking for free loopback device: /dev/loop0
Setting up loopback device: Done
Sleeping for 0 seconds.
Breaking down loopback device:
loop: can't delete device /dev/loop0: Device or resource busy
root     25437  0.0  0.0      0     0 ?        S<   13:25   0:00 [loop0]
Loopback device broken down after 1 tries.
----NEXT PASS----
Loopback devices currently in use:
^C

Right, so it's Linux that's holding on to it and I'm not sure if I like this behavior. I realize losetup can only request Linux to free up the device and it does cleanly report a 'Device or resource busy' but I don't understand why it just doesn't wait a bit until the resource is cleared from the kernel, or at least provides the option to the user to do so. I thought about pathing losetup but now I can't be bothered anymore, so I'm just putting it out there :)