/dev/chat

Gilles

00:00

The initramfs zealot strikes again

slm

can we move all this to initramfs.stackexchange.com or something???

mikeserv

@Gilles - I'm no zealot - I'm not even Jewish?

slm

wait so you don't even know if you're Jewish? ^^^ the question mark...

mikeserv

@slm well, family trees being what they are...

Why would we move it? This is the most fundamental part of your linux-based system - the relationship between userspace and kernelspace.

slm

I was joking...back to Gilles

mikeserv

00:10

Oh - you mean about moving it or about my heritage?

slm

the moving

mikeserv

Why does this bother everybody? And why would anyone downvote the kernel docs? @slm well, I was joking about my heritage...

*crickets*

slm

i would assume gilles DV'd it based on his comment. I didn't do anything beyond commenting here.

@mikeserv - I would assume there's some leftover frustrations from the initramfs Q&A. Keep with it. Perhaps you could move that A to something that's more appropriate. I do not know what that Q would be but I'm just trying to be constructive

mikeserv

Yeah, and his comment is nonsensical, as far as I can tell!

I'm not unreasonable or anything. I just don't see the point in getting upset about it.

slm

I don't know that much about this end of the pool, Gilles is probably the most knowledgeable about it. You seem to know a fair amount about it as well, but all I can do is watch. And try and help.

mikeserv

00:21

So you believe that the linux kernel documentation detailing what initramfs is and how to compile it in as rootfs is irrelevant to a question about how to compile a root file system into the linux kernel?

slm

If you don't understand one of his comments ask him to elaborate.

mikeserv

I did. Of course. I'm not unreasonable.

slm

No I didn't say that, I'm just offering suggestions w/o knowing anything specific on the topic.

mikeserv

I'd be happy to delete it if it's wrong.

slm

If you feel it's right then ignore the DV, it's one persons DV.

mikeserv

00:22

The asker says: I'm building custom Android Kernel based on Cyanogenmod ROM' kernel source code. What I need to do is to add folders and files into the root folder of the OS ("/").

So I posted the doc on rootfs.

Makes sense to me. Am I missing something?

slm

I'd have to re-re-read what you both wrote to be a tie breaker 8-)

mikeserv

I didn't write any of it. I bolded some of it.

slm

@mikeserv - gilles will DV A's that he feels are weaker then his own or if they're egregiously wrong in his opinion.

mikeserv

Yeah, but his answer is technically wrong anyway.

slm

I've never known him to DV out of spite

He's done it to me at times as well, and I've disagreed w/ him at times on it as well, I would take it as one guys opinion and not dwell on it too much. See if the OP finds yours more helpful then his. That and future visitors are the target audience.

mikeserv

00:27

Well, I don't know him to do anything at all. All I know is you said he was a robot. But I don't care - politics are not my forte, you could say. Points and the rest make no difference to me.

It's just that, especially on this issue, there's a lot of undue mystery for, as far as I can tell, no reason.

So I try to be specific. Nothing more.

slm

Yeah so if you think that's a solid A then I'd leave it alone.

He's human just like everyone else here.

mikeserv

Yeah, I don't take it one way or another. Well, I will, so long as I do. But if I'm convinced otherwise, then I'll remove it only because I relish correction - it's nice to be right, especially if you used to be wrong!

I like to learn.

slm

yes everyone has been wrong before they've been right 8-)

mikeserv

Amen.

You know what's cool about init, though? It's just root. That's it. The kernel mounts a root and looks for some executable called init - after that, you can do whatever you want.

And it's really easy - it's just shell script, usually.

You don't need a disk - or even an image file, because you can compile that in.

So a single kernel binary can be a self-contained os.

It's pretty neat.

Graeme

I have this file in my /boot directory ` initrd.img-3.13-1-amd64

mikeserv

00:35

The only really unusual thing that happens in early-userspace generally is switch-root. And the only thing that's strange about it is instead of execing a file with a program, the kernel execs a mount, kind of.

Graeme

I thought I was using initramfs, in fact I probably still am despite the name of the file.

mikeserv

@Graeme - that's your initramfs image file.

It is. You can compile the image in, or keep it separate - or both, if you want.

Graeme

@mikeserv Ok, I didn't know that. I thought it had to be separate.

mikeserv

It's cpio - copy in/out - it's an archive file that the kernel unpacks into / just before it looks for init.

Graeme

I know all that, just thought that it was required to be a separate file.

mikeserv

00:37

cpio archives are kind of cool too, because they're streamed -0 like tarballs - but they're more... hmmm... raw, I guess you'd say.

No, it needn't be.

Graeme

Learn something new every day

Yeah, cpio has its limitations, but perfect for nicely named files

mikeserv

Actually when you do switch-root, the kernel deletes everything in the real root - the kernel's root - it's always there. If you don't do switch-root, you can just mount other disks onto your ramdisk.

And it'll continue to work. You don't need the rest, it's just conventional.

There was a lot of heated discussion in the kernel world when cpio was chosen, actually.

Somewhere out there is a long letter in which Linus defends the choice.

Graeme

@mikeserv what were the alternatives

?

mikeserv

Well, tar.

Everyone was like ! BUT !!! tar!

Graeme

Does seem like the obvious choice I guess, but then I don't know much about the nitty gritty of the formats.

mikeserv

00:41

Everyone knew it, and I don't know why it wasn't chosen, but I think it has to do with cpio more easily handling special files. Or maybe politics and licensing... I have no idea. Only conjecture.

Neither do I - and long hours in info have not expanded upon that understanding very much, either.

Graeme

I discovered something else interesting tonight after playing with my answer here - unix.stackexchange.com/a/122844/48083

The directory that contains the most files in my system (after /var/lib/dpkg/info in an expected first place) is /usr/share/qt4/doc/html

mikeserv

I did get this with tar the other day, though. This was cool - unix.stackexchange.com/a/122736/52934

Graeme

6317 files - that is a well documented API

mikeserv

qt5 is a lot bigger - do you have that one yet?

Faheem Mitha

I need to set up a 32 bit build environment. Any ideas for the easiest / least awful way to do this? virtualbox, linux containers, just plain chroot? something with debootstrap, sbuild/pbuilder?

mikeserv

00:45

Well, you're in a 64-bit system now/

?

Probably debootstrap. And without rebooting, qemu is pretty easy - at least once you get a command line down, anyway.

Faheem Mitha

@mikeserv yes

Graeme

@mikeserv pax can do that too, but without the archive as a mid point.

@mikeserv nah, not yet. Used to do quite a bit of Qt programming. Not so much recently, haven't even played with Qt5 yet.

mikeserv

@Graeme - I've never used it. The POSIX spec is... daunting, to say the least. I'm interested though. Gotta clearer doc than I've found at the POSIX guidelines site?

I never have - I'm usually too involved with trying to fix what I last effed up in the terminal to get far enough along with the gui, unfortunately...

Graeme

Oh, yes. The documentation is what makes it - there really is nothing else like it. If you use QtCreator, you get everything right there at your fingertips.

mikeserv

01:00

@Graeme I meant pax - I've seen the qt docs though, and their size is daunting, but at least they're friendly. Pax, in my experience, is another story.

By the way - this is good: unix.stackexchange.com/questions/122806/…

You can get the same functionality with -printf and | . /dev/stdin too, but I like seeing people use find with sh and the like - it's creative.

Graeme

@mikeserv Its a fun one to play with. Finding out that Qt basically has more documentation than the rest of my system was an interesting result.

mikeserv

They're huge - and with 5.2 - they're mobile/desktop/unix/windows agnostic.

It's the future.

Graeme

@mikeserv more than Java I find (but then Java offers better backward compatibility).

@slm, that bash hackers wiki is a really good resource. It must be fairly new though, I have come across it a couple of times before, but only fairly recently.

Braiam

01:27

emacs + xterm expert around?

slm

@Graeme - you might want to make a Q specifically for your find command on the inode Q.

mikeserv

@Graeme eek. Java. I hate Java. It's an entire virtual machine, and all of their nasty licensing in/outs over the past decade have only turned bad to worse.

@slm what does that mean? Why would you make a question for an answer - you said something to me about that the other day - that and swimming practice... memory's fuzzy...

slm

@Graeme Yeah I had it bookmarked, the problem is going through the list of resources and finding things now. I pretty much have everything "bookmarked" in delicious. I'm almost at 20K links thus far.

@mikeserv Yes sometimes an A to a Q can be better served by making a customized Q for rather then leave it on a Q that's extremely specific b/c of the OP that asked it.

mikeserv

What, for exposure or something? Damn, I have got to turn down the volume - that almost gave me a heart attack!

slm

In graeme's case his A includes the ideal Q for it: "How can I list the top 50 directories in the filesystem containing the most files/directories in their first level"

@Graeme ^^^^^

mikeserv

01:37

And then you answer it yourself?

slm

yes

mikeserv

Hm.

Braiam

of course

slm

think of it as blogging

Braiam

mm... we are hot tonight

@slm in the QA style, tho

mikeserv

01:38

You just get some new pants or something?

slm

of course

Braiam

I don't know how we end here

Graeme

@slm, good idea. There was another question I was thinking about doing this with...

3

Q: how do I do this: dd if=coolstuff.iso of=(ssh kev@mypi )

the card reader on my laptop doesn't want to work. can I use dd (or some other tool) to write an image to a networked disk. I am trying to replace one raspberry pi distro with another. The SD card has 6gb free and uses only 2gb. from the SD card $ sudo parted -l Model: SD SU08G (sd/mmc) Disk ...

shell dd

slm

@Graeme I can ask it for you and then you can answer it

if you like

"Find the top 50 directories containing the most files/directories in their first level?"

Graeme

I am in two minds whether or not to just do my own Q&A here or just heavily edit the original question

slm

01:43

too late, just asked it for you

I think it's a useful Q by itself. We can reference it when dealing with inode or general house cleaning Q's

It's generally best to leave OP Q's alone and not hijack them too much

Put your answer in and then I can accept it

@Graeme - I think most of my Q's have been for A's that I had in mind, w/o a Q to put them on. I've also lifted A's from Q's and made new homes for them on my own Q's

@Graeme - use it as a teaching moment and really explain the hell out of the A. That way it can be a canonical A more then some other 1/2 @ssed one 8-)

@Graeme can you add some sample output of what it will show when run?

Graeme

@slm sure, just add a files with newlines alternative now.

slm

@Graeme - you're adding it or am I?

Graeme

@slm *adding, sorry

slm

@Graeme - OK that makes more sense 8-) or like this...

Braiam

@Graeme if you press the up arrow you can edit your last message ;) like this

Graeme

01:55

@Braiam Ok, so you still get the ping for edits, I see

Braiam

yeah

slm

@Graeme - yes, terdon will ping the heck out of ya, I always disable them...with the edits....apparently so do I 8-)

Braiam

02:09

xterm does read ~/.Xdefaults right?

Graeme

@slm, have I missed anything?

slm

@Graeme - sample output and then I can accept it

if they use sort -h it will put the output in human readable too

Graeme

@slm I thought that just already sorted sizes that already had M, G etc appended

@slm btw, don't try to run it without the -xdev - the output was taking a long time. I had to stop it when I realised what was causing it.

casey

02:26

@Braiam it does for me

Braiam

@casey didn't for me :( askubuntu.com/a/442661/169736

had to use something else

casey

@Braiam did you try .xresources instead? you could also run xrdb -m <file> to merge an arbitrary file of X resources

Braiam

@casey read the answer again :(

Graeme