Making a live CD

[eggbert]

I am interested in making a very simple live CD with the following programs on:

smartmontools
ddrescue
gparted
testdisk
ophcrack

It doesn't need any drivers particulary, doesn't need any networking stuff, just those programs and whatever things they depend on. It would just need a very simple xwindows system.

I work in a computer shop and we use these utilities but at the moment don't have one livecd with all these on. I know very little about linux. Is it best to just install linux on a computer, change it to my needs then use the live scripts to turn it into a live CD or would it be better to try and modifiy an existing live CD?
Parted Magic live CD is probably the closest to what I want but I haven't a clue how to customize it.

Thanks.

[Ben Cotton]

Knoppix is a very popular distro for making custom live CDs. You can look in the Knoppix forum here:

http://www.linuxforums.org/forum/knoppix-help-forum/

and at the Knoppix Remastering howto:

Knoppix Remastering Howto - Knoppix Documentation Wiki

[ryptyde]

Check out SystemRescueCD it may be just what you can use.

[eggbert]

Thanks for the advise, I will give that a try. Before you replied I was actually trying to modify ophcrack which is built with slax but not really getting anywhere. I found gparted, ddrescue and smartmontools as slax .lzm modules and stuck them into the iso in the 'modules' folder but when I booted it up it just kept saying the modules were corrupt...do you know why this might be? I am looking for a quick and dirty way of doing this, i.e. without actually installing linux and doing it all from windows but maybe this isn't going to happen.

I have systemrescueCD, it is also very close to what I want but doesn't have ophcrack and does have a lot of stuff which I don't need i.e. firefox, networking.

Thanks.

[ryptyde]

Taken from the SystemRescueCD site:

It is possible to make customized versions of the CD. For example, you can add your own scripts, to make an automatic restoration of the system. It's also possible to burn a customized DVD, with SystemRescueCd and 4.2 GB for your data (backup for example). Read the manual for more details. There is a new manual chapter that explains How you can burn a DVD+RW from SystemRescueCd

It is very easy to install SystemRescueCd on an USB stick. That's very useful in case you can't boot from the CD drive. You just have to copy several files to the stick and run syslinux. The install process can be done from Linux or Windows. Follow instructions from the Manual for more details.

maybe you can get what you want that way.

[i92guboj]

The easiest solution would be to pick any livecd and then add an statically linked binary of ophcrack anywhere.

The rest of the stuff you mention is in 99% of the livecds, I think. It's fairly common stuff. So, you would just need to edit the iso, and add ophcrack into the bin directory or wherever that livecd has the binaries.

There can be some poblems, though.

As I said, you MUST use an statically linked version of the program, because that way you have a better change to get it working without any incompatibility with any lib on the livecd.

That might or might not be possible depending on how the program is programmed, distributted, if it's or not opensource (I never heard of it, so I don't know...).

Another potential problem is that the live can be sqashed. If it's compressed with sqashfs, you will need to decompress the image to add the files and then compress it back.

[eggbert]

Hello, thanks for the advise. Rip-linux or system rescue CD would seem a good place to start. I realise that I will have to uncompress the filesystems on most of these, but are you saying that I can just delete and add programs like you say? I am so used to Windows where things have to be installed properly in the registry, etc. etc. Also I have noticed some programs need certain libraries, i.e. libc, can you just add these in the same way or do they need to be 'registered' somehow?
I was also wondering about drivers, how are these added and removed?
Is it possible to run one of these live cds and actually work on the filesystem in RAM, then write it back modified to a USB drive somehow?
Anyway, I think I should install something like ubuntu and have a play around with it before I do anything like that, I don't even know basic linux commands or how to install/uninstall/update programs so it might be a bit ridiculous jumping into something like this.

Thanks.

P.S. What is a statically linked binary?

[i92guboj]

Hello, thanks for the advise. Rip-linux or system rescue CD

Two good choices. I use them quite a lot for many purposes.

I realise that I will have to uncompress the filesystems on most of these, but are you saying that I can just delete and add programs like you say?

Mostly: yes. There are some things to consider. Ultimately, you just will need to do some tests to check that the binaries you are adding are compatible with the libs on your cdrom OR that they are statically linked (so, they won't need those libs because all the code will be already linked into the proper binary).

I am so used to Windows where things have to be installed properly in the registry, etc. etc. Also I have noticed some programs need certain libraries, i.e. libc, can you just add these in the same way or do they need to be 'registered' somehow?

You don't need to do anything special. Just, ensure that the system is consistent, and all the binaries are compatible with each other. For example, if you add a binary file called "foo" into /bin, you can do "ldd /bin/foo" to check if the binary is consisten, and it can link about all the needed libs.

If it isn't, then you most likely need to get a correct binary package that supports the concrete versions of the libs you have installed, or, compile it statically. That can be done in one or another way depending on the concrete package, though, most rescue tools have a configure option that can be used before compiling it to make it compile statically. It's a good thing for this tools, because they often have to be run in hostile environments :P

libc is already in your cdrom (or uclib or any equivalent). It's the core C library of any linux system.

I was also wondering about drivers, how are these added and removed?

Some times are external entities, but most times, the drivers are included in the kernel. They can be included statically into the kernel, or they can be compiled as separate modules, which are small .ko files that can be found around /lib/modules/

The configuration and compilation of the linux kernel could take a book. So, if you want to make a custom kernel for your livecd, you are going to have to practise a bit.

Open a new thread if you need help on that.

Is it possible to run one of these live cds and actually work on the filesystem in RAM, then write it back modified to a USB drive somehow?

Mmmm, your requirements are starting to sound suspiciously similar to some guide about Gentoo. Maybe you should start from scratch and use Gentoo as the foundation for your livecd/dvd/usb:

HOWTO Gentoo LiveCD and LiveUSB - Gentoo Linux Wiki

Just a thing to consider. Maybe it doesn't suit you, but there's the info in case you want to take a look.

To answer your original question: I am not a master myself. But, well, you can just mount the compressed image or the iso (or the cd, if it's not compressed) into any arbitrary mount point in your home dir or wherever you preffer. Then, copy it the whole contents anywhere in your hard drive, make the modifications, and then burn it again to a bootable cd or iso image. I am not a master on bootable cdroms, so, I can't help on that. But there should be enough info on how to do this on the net.

Anyway, I think I should install something like ubuntu and have a play around with it before I do anything like that, I don't even know basic linux commands or how to install/uninstall/update programs so it might be a bit ridiculous jumping into something like this.

If you really want to get in touch with these things, ubuntu is going to be of little help. You should get your hands dirty if you really want to learn all this obscure stuff, and use either lfs or gentoo (my choice).

I advice you to:

1.- Get a look at the Gentoo handbook (pick one depending on the way you want to install and your architecture):
Gentoo Linux Documentation -- Gentoo Handbook

2.- Subscribe to forums.gentoo.org and feel free to ask anything you need to know (when installing, or before installing) on the Installation section of those forums.

You can poke me with a pm if you want on the Gentoo forums. I'm i92guboj there as well. I promise I will take a look at any question (though I can't guarantee that I can answer all of them).

After installing Gentoo and using it for some weeks, you will start to see a lot clearer what I am talking about. For one, the kernel configuration and compilation will seem much clearer to you. Gentoo has also the tools you need to create livecds painlessly, and lots of rescue tools on portage (it's package manager).

Besides that, by compiling the whole contents of the livecd from source, you ensure that there's no incompatibility between the binaries there, so, you can change anything without risking stability. Compiling external drivers if needed will also be easy, because Gentoo installs a valid toolchain and the kernel sources from the very start, and you would need to install and set that up yourself on any other distro if you plan to compile custom stuff.

P.S. What is a statically linked binary?

I think that this is partially answered already. It's a binary program that doesn't need external libs to run, because all the code is self contained. That can be chosen at compile time, on one way or another depending on the program itself and it's makefiles.

Whatever you choose, luck with that.

[Dies]

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