To Create a Live Linux CD/DVD

A live CD is a bootable CD that contains the whole operating system and any applications you want to run from the CD. With the increasing popularity of DVD and Blu-ray drives, there is even a live DVD. A live CD is useful when you want to copy your existing Linux system to a CD and run it on multiple computers. In this post, I show how I normally create a live CD.

Rebuild a kernel with SquashFS and UnionFS patch

A new kernel should be built with SquashFS and UnionFS patches. The live CD will have a huge file that is actually a SquashFS image containing a copy of your existing Linux system. We will use UnionFS so that any changes to the read-only SquashFS will be saved to the volatile memory. Download the patches from the following locations.

• squashfs.sourceforge.net
• unionfs.filesystems.org

After patching the kernel and rebuilding it, install the new kernel.

Make a SquashFS image of an existing Linux system

A SquashFS image needs to be created from an existing Linux system. Copy the contents of the Linux filesystem to an empty directory, assuming the filesystem is mounted at /mnt.

mkdir /tmp/livecd
cd /mnt
tar cf - . | (cd /tmp/livecd; tar xf -)

Empty the contents of fstab so that the live CD will not mount any hard disk partition, including the original root partition.

cp /dev/null /tmp/livecd/etc/fstab

Create a squashfs image.

mksquashfs /tmp/livecd /tmp/linuxfs.sqz -comp xz -b 262144 -Xdict-size 196608 -no-xattrs -e boot lost+found selinux srv

Create a Custom InitRamFS image

This is a tricky part of the job. Basically, the init script of the initramfs image will mount the CD-ROM, then mount the SquashFS image, and then mount a UnionFS. Refer to this post on building an initramfs image.

Create a Live CD structure.

Create an empty directory which will be the contents of live CD. The live CD will contain:

• SquashFS image (named linuxfs.sqz, for example)
• isolinux.bin and isolinux.cfg
• kernel
• initramfs image

Finally, create an ISO image for the live CD.

genisoimage -V LIVECD -b isolinux.bin -c boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table /tmp/isofs > ~/livecd.iso

Burn the ISO image.

cdrskin -v dev=/dev/sr0 speed=8 driveropts=burnfree ~/livecd.iso

Manually Creating initrd / initramfs to Boot Linux

Initrd and initramfs files are used together with a Linux kernel and a bootloader (such as GRUB and syslinux) to start up Linux in many different ways. Linux distributions provide prepackaged kernels and convenient tools for creating initramfs, but I like to build my own kernel and initramfs because it allows me to customize the boot process. For instance, one can choose to boot from the local disk or the network with the help of initramfs and some user-defined boot parameters. Here's a list of things that I'd like to achieve with my custom initramfs.

1. Boot from a live CD
2. Boot from a read-only filesystem image, compressed with SquashFS
3. Copy the filesystem image to a RAM disk and run Linux entirely within memory
4. Boot Linux from a USB flash drive or a Firewire disk
5. Boot Linux from a local disk partition
6. Boot Linux from a network drive
7. Run a rescue shell without booting Linux
8. Start a kdrive X-server and run gparted, partclone or partimage

In this post, I show how I normally create initrd / initramfs files. For this tutorial, the following Debian/Ubuntu packages are needed:

• busybox
  provides small essential utilities for booting and rescue shell.
• cpio
  is used to create the actual initramfs format.
• e2fsprogs, jfsutils, etc.
  provides fsck to check Linux filesystems and replay any stale journal before booting
• lzma or xz-utils
  compresses the initramfs
• pciutils
  is used to detect PCI hardware
• unionfs-fuse
  makes it possible to use read-only Linux systems, such as live CD and filesystem images
• unzip
  is used to apply local settings when booting a live CD.
• v86d
  is used to set the screen resolution for framebuffer screens

First, create a text file with a list of files to put in initramfs. The following is an example of such file:

bin/busybox
bin/dash
bin/mount
etc/filesystems
etc/fuse.conf
etc/group
etc/modprobe.d
lib/ld-linux.so.2
lib/i386-linux-gnu/libacl.so.1
lib/i386-linux-gnu/libattr.so.1
lib/i386-linux-gnu/libblkid.so.1
lib/i386-linux-gnu/libbz2.so.1.0
lib/i386-linux-gnu/libcom_err.so.2
lib/i386-linux-gnu/libc.so.6
lib/i386-linux-gnu/libdl.so.2
lib/i386-linux-gnu/libe2p.so.2
lib/i386-linux-gnu/libext2fs.so.2
lib/i386-linux-gnu/libfuse.so.2
lib/i386-linux-gnu/libkmod.so.2
lib/i386-linux-gnu/libmount.so.1
lib/i386-linux-gnu/libm.so.6
lib/i386-linux-gnu/libpci.so.3
lib/i386-linux-gnu/libpthread.so.0
lib/i386-linux-gnu/libresolv.so.2
lib/i386-linux-gnu/librt.so.1
lib/i386-linux-gnu/libselinux.so.1
lib/i386-linux-gnu/libsepol.so.1
lib/i386-linux-gnu/libuuid.so.1
lib/i386-linux-gnu/libx86.so.1
lib/i386-linux-gnu/libz.so.1
lib/modules/3.6.2-586mmx/kernel/drivers/ata
lib/modules/3.6.2-586mmx/kernel/drivers/block/loop.ko
lib/modules/3.6.2-586mmx/kernel/drivers/cdrom/cdrom.ko
lib/modules/3.6.2-586mmx/kernel/drivers/connector/cn.ko
lib/modules/3.6.2-586mmx/kernel/drivers/firewire/firewire-core.ko
lib/modules/3.6.2-586mmx/kernel/drivers/firewire/firewire-ohci.ko
lib/modules/3.6.2-586mmx/kernel/drivers/firewire/firewire-sbp2.ko
lib/modules/3.6.2-586mmx/kernel/drivers/i2c/algos/i2c-algo-bit.ko
lib/modules/3.6.2-586mmx/kernel/drivers/scsi/sd_mod.ko
lib/modules/3.6.2-586mmx/kernel/drivers/scsi/sr_mod.ko
lib/modules/3.6.2-586mmx/kernel/drivers/usb/host/ehci-hcd.ko
lib/modules/3.6.2-586mmx/kernel/drivers/usb/host/ohci-hcd.ko
lib/modules/3.6.2-586mmx/kernel/drivers/usb/host/uhci-hcd.ko
lib/modules/3.6.2-586mmx/kernel/drivers/usb/host/xhci-hcd.ko
lib/modules/3.6.2-586mmx/kernel/drivers/usb/storage/usb-storage.ko
lib/modules/3.6.2-586mmx/kernel/drivers/video
lib/modules/3.6.2-586mmx/kernel/fs/ext3/ext3.ko
lib/modules/3.6.2-586mmx/kernel/fs/ext4/ext4.ko
lib/modules/3.6.2-586mmx/kernel/fs/fat/fat.ko
lib/modules/3.6.2-586mmx/kernel/fs/fat/vfat.ko
lib/modules/3.6.2-586mmx/kernel/fs/fuse/fuse.ko
lib/modules/3.6.2-586mmx/kernel/fs/isofs/isofs.ko
lib/modules/3.6.2-586mmx/kernel/fs/jbd2/jbd2.ko
lib/modules/3.6.2-586mmx/kernel/fs/jbd/jbd.ko
lib/modules/3.6.2-586mmx/kernel/fs/jfs/jfs.ko
lib/modules/3.6.2-586mmx/kernel/fs/nls/nls_cp437.ko
lib/modules/3.6.2-586mmx/kernel/fs/nls/nls_iso8859-1.ko
lib/modules/3.6.2-586mmx/kernel/fs/nls/nls_utf8.ko
lib/modules/3.6.2-586mmx/kernel/fs/reiserfs/reiserfs.ko
lib/modules/3.6.2-586mmx/kernel/fs/squashfs/squashfs.ko
lib/modules/3.6.2-586mmx/kernel/fs/xfs/xfs.ko
lib/modules/3.6.2-586mmx/kernel/lib/crc16.ko
lib/modules/3.6.2-586mmx/kernel/lib/crc-t10dif.ko
lib/modules/3.6.2-586mmx/modules.alias
lib/modules/3.6.2-586mmx/modules.dep
lib/modules/3.6.2-586mmx/modules.dep.bin
sbin/blkid
sbin/e2fsck
sbin/jfs_fsck
sbin/modprobe
sbin/v86d
usr/bin/lspci
usr/bin/unionfs-fuse
usr/bin/unzip

Then, create an empty directory, for example, /tmp/initrd and copy the files listed in the above-mentioned text file (called rd354.txt) to the new directory.

mkdir /tmp/initrd
cd /
tar cvhf - -T rd354.txt | (cd /tmp/initrd; tar xf -)

Then, create the necessary directory structure under /tmp/initrd:

cd /tmp/initrd
mkdir -p dev media mnt proc root sys tmp

Since I chose to use busybox, I need to create symbolic links to busybox in /bin. Busybox provides incomplete functionality for modprobe, mount, sh and unzip, so I removed their symbolic links.

cd /tmp/initrd/bin
for f in $(./busybox --list); do [ -e $f ] || ln -s busybox $f ; done
rm modprobe unzip

Then, create essential device nodes in /tmp/initrd/dev:

cd /tmp/initrd/dev
MAKEDEV std fb0 fd0 sda sdb scd
mknod console c 5 1
mknod fuse c 10 229
chmod 666 fuse

Now, create an init script. The contents of this init script is crucial for customization of the boot process. For an example of init script, please read this post. The example script is capable of booting a live CD and running Linux from memory disk in addition to booting Linux from hard drives and USB flash. Just put the init script at the top level of initrd tree and the etc subfolder, and make it executable.

chmod 777 /tmp/initrd/init
chmod 777 /tmp/initrd/etc/init

Then, use cpio and lzma to create an initramfs file. This assumes that the kernel was compiled with CONFIG_RD_LZMA option enabled.

cd /tmp/initrd
find . | cpio -H newc -o | lzma -c > ../initram.lzm

A file named initram.lzm will be created. If you want to create an old-style initrd file instead, use the mkcramfs command. This assumes your kernel has built-in cramfs support (CONFIG_CRAMFS):

mkcramfs /tmp/initrd /boot/initrd.bin

Copy the kernel and the initramfs file to your boot directory. Finally, edit your bootloader's configuration file. The following is the contents of a sample syslinux.cfg:

LABEL debian
KERNEL 314.lnx
INITRD /initrd/initram.lzm
APPEND root=/dev/sda7

LABEL sid
KERNEL 314.lnx
INITRD /initrd/initram.lzm
APPEND boot=usb label=SID edd=off vmode=800x600

LABEL bfile
KERNEL 314.lnx
INITRD /initrd/initram.lzm
APPEND boot=loop root=/dev/sda1

LABEL ram
KERNEL 314.lnx
INITRD /initrd/initram.lzm
APPEND boot=ram ramdisk_size=524288 root=/dev/sda1

Getting Eclipse to Work with MinGW C/C++ Compilers

Eclipse is one of my favorite programming environment which is used to develop C, C++ and/or Java software efficiently. Let's set up Eclipse so that we can use it to work with MinGW C/C++ compiler and Java.

1. First, install MinGW (as shown in this post). You have two choices for the MinGW compiler:
   
   • MinGW (www.mingw.org)
     The original GCC toolchain for 32-bit Windows only
   • MinGW-w64 (mingw-w64.sourceforge.net)
     New breed of tools that allow you to compile for both 32-bit and 64-bit Windows

   I prefer the original MinGW compiler to MinGW-w64, but individual tastes may vary. Make sure that you add the folder containing gcc.exe to the PATH environment variable.

2. Then, install JRE because Eclipse won't run without it. If you want to develop Java, then install JDK (Java SE or Java EE) instead of JRE.

3. Now, download Eclipse IDE for C/C++ Developers (eclipse-cpp-juno-win32.zip) and unpack it. You need it to develop C/C++ programs.

4. If you also want to develop Java, then download Eclipse IDE for Java Developers (eclipse-java-juno-win32.zip). Just unpack the Java Developer package into the same folder as Eclipse for C/C++, avoiding to overwrite existing files.

5. Create a shortcut on your desktop that points to the Eclipse program (eclipse.exe). To start Eclipse, double-click the Eclipse shortcut that you just created.

6. Let's test our Eclipse installation and create a simple C++ program. Start a new C++ project (File->New->C++ Project). Type in any Project name, and select Empty Project under Executable Project types. Choose MinGW GCC for toolchains. Click Finish.

   

   Once a new C++ project is open, create a new source file (File->New->Source File).

   

   Try typing in a simple code like the following:

   #include <iostream>
   using namespace std;
   
   int main()
   {
     cout << "Hello, boys and girls.\n";
     return 0;
   }

   Save the project (File->Save). Build the project (Project->Build Project). If the build was successful, run the generated program (Run->Run, or Ctrl+F11).

MinGW: Compiling LZO Compression Library

LZO, short for Lempel-Ziv-Oberhumer, is compression software that is designed for decompression speed. I compiled the LZO library like this.

tar xzvf lzo-2.03.tar.gz
cd lzo-2.03/
./configure --prefix=/mingw
make
make install

I only got a static library liblzo2.a. So I had to convert it to a DLL.

gcc -shared -o liblzo2-2.dll -Wl,--out-implib,liblzo2.dll.a -Wl,--whole-archive /mingw/lib/liblzo2.a -Wl,--no-whole-archive -L/mingw/lib -lwinmm

Compiling gtkmm for Windows with MinGW

gtkmm is a C++ wrapper library that makes it possible to write C++ programs with GTK+. After compiling the GTK+ library, you can build gtkmm as follows.

1. libsigc++ 2.2.10

   libsigc++ implements a typesafe callback system for standard C++. Download the libsigc++ source code from here and compile it:

   ./configure --prefix=/mingw
   make
   make install

2. glibmm 2.32.1

   glibmm is a C++ wrapper for Glib. Compile it like this:

   ./configure --prefix=/mingw
   make
   make install

3. atkmm 2.22.6

   atkmm is a C++ wrapper for ATK. Compile it like this:

   ./configure --prefix=/mingw
   make
   make install

4. cairomm 1.10.0

   cairomm provides C++ interface to the Cairo library. Compile it like this:

   ./configure --prefix=/mingw
   make
   make install

5. pangomm 2.28.4

   pangomm is a C++ wrapper for Pango. Compile it like this:

   ./configure --prefix=/mingw
   make
   make install

6. gtkmm 3.4.0

   gtkmm is a C++ wrapper for GTK+. Build it as follows:

   ./configure --prefix=/mingw
   make
   make install

Building GraphicsMagick

GraphicsMagick is a powerful tool for processing image files. I'm using MinGW to build GraphicsMagick for Windows.

1. zlib 1.2.7

   Download the zlib source (zlib-1.2.7.tar.gz) and unpack it.

   tar xzvf zlib-1.2.7.tar.gz
   cd zlib-1.2.7

   Compile and install zlib.

   make -f win32/Makefile.gcc
   cp -iv zlib1.dll /mingw/bin
   cp -iv zconf.h zlib.h /mingw/include
   cp -iv libz.a /mingw/lib
   cp -iv libz.dll.a /mingw/lib

2. bzip2

   Now download bzip2 source from bzip.org and unpack it.

   tar xzvf bzip2-1.0.6.tar.gz
   cd bzip2-1.0.6

   Change line 78 of bzlib.h to read:

   #if defined(_WIN32) && !defined(__MINGW32__)

   Compile and install bzip2.

   make
   cp bzlib.h /mingw/include/
   cp libbz2.a /mingw/lib

3. liblzma

   Get the XZ Utils source code and unpack it. Go to the src/liblzma folder and compile liblzma like this:

   tar xzvf xz-5.0.4.tar.gz
   cd xz-5.0.4
   ./configure --prefix=/mingw
   cd src/liblzma
   make
   make install

4. libpng 1.5.12 and libjpeg 8d

   Compile libpng and libjpeg as follows:

   ./configure --prefix=/mingw
   make
   make install

5. libjasper

   Compile Jasper:

   ./configure --prefix=/mingw
   make
   make install

   If you encounter an error "undefined reference to _sleep", replace sleep() with _sleep with a factor of 1000 in the code:

   _sleep(1000)

6. JBig

   Get jbigkit from here.

   make
   cp libjbig/*.h /mingw/include
   cp libjbig/*.a /mingw/lib

7. libtiff 4.0.2

   Compile libtiff like this:

   ./configure --prefix=/mingw
   make
   make install

   If the shared library libtiff-5.dll is not generated and you want to create it manually, use such a command as the following and update libtiff.la accordingly:

   gcc -shared -o libtiff-5.dll -Wl,--out-implib,libtiff.dll.a -Wl,--whole-archive /mingw/lib/libtiff.a -Wl,--no-whole-archive -L/mingw/lib -ljpeg -ljbig -llzma -lz

8. freetype

   Compile freetype:

   ./configure --prefix=/mingw
   make
   make install

9. libxml2

   Compile libxml2:

   ./configure --prefix=/mingw
   make
   make install

10. libwmf 0.2.8.4

    Compile libwmf:

    ./configure --prefix=/mingw
    make
    make install

11. Little CMS

    Compile liblcms:

    ./configure --prefix=/mingw
    make
    make install

12. Build GraphicsMagick

    Get GraphicsMagick code and build it like this:

    ./configure --prefix=/mingw --with-gs-font-dir='C:/Windows/Fonts' --with-windows-font-dir='C:/Windows/Fonts' LIBS='-ljbig'
    make 
    make install

Creating a PDF document from JPEG files

GraphicsMagick comes in handy when you want to convert scanned JPEG images to a PDF document:

gm convert *.jpg doc.pdf