Customizing a Trisquel iso

To customize a Trisquel .iso image, you must first download it and place it in an empty directory. Open a terminal and go to that directory, then follow these steps. Note that your architecture must be same as the target, i.e. you cannot customize a 64 bit iso from a 32 bit system (beyond editing the preseed file).

Contents

• 1 Unpacking
• 2 The Preseed File
• 3 Making Changes
• 4 Cleaning up and setting your computer back to normal
• 5 Repacking
• 6 Optional test

Unpacking

• Become root. All commands below will be run as root.

 sudo su

• Create an empty directory and mount the iso on it, then extract the contents:

 mkdir tmp
 mount -o loop trisquel-original.iso tmp
 rsync -a tmp/ src/
 umount tmp

• Extract the squashed image files from casper/filesystem.squashfs. Also, create a 'jail' directory (to restrict the commands for the new configuration to affect your own system); This is where most changes take place:

 mount src/casper/filesystem.squashfs tmp -t squashfs -o loop
 mkdir jail
 rsync -a tmp/ jail/
 umount tmp

The Preseed File

Trisquel comes with a preseed file which allows preloading values into the debconf database. You can find the file at src/preseed/trisquel.seed. The file contains commented examples on the changes it can make, like changing the default locale, setting a static network configuration, or automagically installing an extra set of packages before the live-to disk install process (which you need internet access during the install to do).

Making Changes

Now you have the Trisquel system files in the jail directory, and you can start to apply changes.

• First, we will backup some important files (Internet connection, data about mounted filesystems in the LiveCD and the repositories):

 mkdir orig
 cp -pL {edit,orig}/etc/hosts
 cp -pL {edit,orig}/etc/resolv.conf
 cp -pL {edit,orig}/etc/mtab
 tar cf orig/etc-apt-conf.tar -C edit/etc apt

• Also the start-up scripts:

 SCRIPTS="sbin/start-stop-daemon usr/sbin/invoke-rc.d usr/sbin/service"
 for i in $SCRIPTS
 do
 mv "$CHROOT/$i" "$CHROOT/$i.REAL"
 cat <<EOF > "$CHROOT/$i"
 #!/bin/sh
 echo
 echo "Warning: Fake /$i called, doing nothing"
 EOF
 chmod 755 "$CHROOT/$i"
 done
 
 cat <<EOF > "$CHROOT/usr/sbin/start"
 #!/bin/sh
 echo
 echo "Warning: Fake start called, doing nothing"
 EOF
 
 cat <<EOF > "$CHROOT/usr/sbin/stop"
 #!/bin/sh
 echo
 echo "Warning: Fake start called, doing nothing"
 EOF
 chmod 755 $CHROOT/usr/sbin/start $CHROOT/usr/sbin/stop

The above commands backup and remove the programs that start or set-up some services that run when you start-up your computer. If you are curious, you can type 'man cat' and 'man sh' in your terminal. Then press / and then some words that you would like to find (for example << while reading the manual of sh; this is the procedure to know how almost any linux command works).

• This is optional and you don't really have to do it (copy your currently available packages to the new system and make a list of the packages that you have installed in your system):

 rsync /var/cache/apt/archives/*.deb /edit/var/cache/apt/archives
 aptitude search --disable-columns -F '%p=%V' '~i' >  installed.list
 aptitude search --disable-columns -F '%p=%V %M' '~M' > jail/automatically-installed.list
 aptitude search --disable-columns -F '%p=%V %M' '~i !~M' > jail/manually-installed.list
 aptitude search --disable-columns -F '%p=%V %c' '!~i !~v' > jail/purged.list
 aptitude search --disable-columns -F '%p=%V' '!~aupgrade' > jail/tobe-upgraded.list

If you want to know what all this gibberish means, type 'aptitude' in your terminal, press CTRL T, go to 'Help' and select the manual. When you are there, you can press / to look for each of the terms (try %c, for instance.)

• You need to mount some parts of your current system to work and install packages:

 mount -t proc none jail/proc
 mount -t devpts none jail/dev/pts
 mount -t sysfs none jail/sys

• To install or remove packages, you need to enter the working directory using chroot:

 cp /etc/resolv.conf jail/etc
 chroot jail

The first command allows you to have network access. The second command puts you "inside" your new system.

• It may be necessary to update your locale to run some (python) code:

 aptitude update
 aptitude upgrade locales
 grep en_US /usr/share/i18n/SUPPORTED > /etc/locale.gen
 locale-gen en_IE.UTF-8
 dpkg-reconfigure locales
 LC_ALL="en_IE.UTF-8"
 LANG="en_IE.UTF-8"
 LANGUAGE="en_IE.UTF-8"
 export LC_ALL LANG LANGUAGE

• You can now start doing all the changes that you need. You could install a 'package', for example:

 aptitude install package   # Install 'package'

• Optionally, if you created the list of packages which are installed in your current system, you can set them in the new system like this (and be ready to deal with unmet dependencies):

 aptitude --schedule-only upgrade $(cut -d'=' -f1 /tobe-upgraded.list)
 aptitude --schedule-only purge $(cut -d'=' -f1 /purged.list)
 aptitude --schedule-only install $(cat /installed.list)
 aptitude markauto $(awk 'BEGIN{FS="="} {print $1}' /automatically-installed.list)
 aptitude install

Note how we didn't really use the 'manually-installed.list'. The intention is to learn a little along the way. Hopefully, you will search for the meaning of the commands posted here.

• Update the hardware information from an Internet database (this is optional and not completely required):

 update-pciids
 update-usbids

Cleaning up and setting your computer back to normal

You need to undo some of the changes that you have made to set your computer to work nicely when you are done.

• First, re-enable services within the system that you just created:

 dpkg-divert --rename --remove /sbin/initctl
 SCRIPTS="sbin/start-stop-daemon usr/sbin/invoke-rc.d usr/sbin/service"
 for i in $SCRIPTS
 do
 mv "/$i.REAL" "/$i"
 done
 rm -f /usr/sbin/start
 rm -f /usr/sbin/stop

• Then, detach the created system from your actual computer:

 exit
 umount -fl jail/dev/pts
 umount -fl jail/dev
 umount -fl jail/sys
 umount -fl jail/proc

• This is optional (update gconf and kernel), but you should do it if you installed or modified a (working) kernel:

 chroot jail update-gconf-defaults
 chroot jail update-initramfs -u

• This is also optional and not completely needed. It is better if you remove the packages that you downloaded to make your ISO smaller and the compression faster:

 find jail |grep [.-]old$ | xargs -r rm -v
 find jail |grep [.-]bak$ | xargs -r rm -v

 for dir in jail/var/lib/update-notifier/user.d/ jail/var/lib/apt-xapian-index/
 do
 [ -d $dir ] || continue
 find $dir -type f |xargs -r rm
 done

 rm -rf jail/tmp/*

• You should now put the default Internet configuration and the table of mounted devices as they were in the Live-CD:

 rm -f jail/etc/hosts jail/etc/resolv.conf jail/etc/mtab \  jail/root/.bash_history jail/root/.Xauthority \  jail/etc/resolvconf/resolv.conf.d/original \  jail/etc/resolvconf/resolv.conf.d/tail
 
 rm -v jail/usr/lib/locale/locale-archive
 
 cp -p orig/etc-hosts jail/etc/hosts
 cp -p orig/etc-resolv.conf jail/etc/resolv.conf
 cp -p orig/etc-mtab jail/etc/mtab

• If you replaced the kernel or the boot scripts with a working one, copy the new kernel binary and initrd image as needed:

 KERNEL="$(chroot jail echo `uname -r`)"
 cp "jail/boot/vmlinuz-$KERNEL" src/casper/vmlinuz
 cp "jail/boot/initrd.img-$KERNEL" src/casper/initrd
 
 cp jail/boot/vmlinuz-custom src/isolinux/vmlinuz
 cp jail/boot/initrd.img-custom src/isolinux/initrd

Repacking

• After your modifications are done, you will need to rebuild the squashfs and .iso images. Install squashfs-tools:

 apt-get install squashfs-tools genisoimage

• Update the list of packages and remove the old squashfs:

 chroot jail dpkg-query -W --showformat='${Package} ${Version}\n' > ./filesystem.manifest
 mv -f ./filesystem.manifest src/casper/filesystem.manifest

 rm src/casper/filesystem.squashfs

• To compress your new system into the squashfs file, you have four options:

1. Normal version (this will work with most BIOS):

 mksquashfs jail src/casper/filesystem.squashfs

2. Compact (using a bigger block size), but slower to compress:

 mksquashfs jail src/casper/filesystem.squashfs -b 104857

3. More compact (with xz compressor) and slower to compress:

 mksquashfs jail src/casper/filesystem.squashfs -comp xz

4. Really compact (using a bigger block size and xz compressor) and even slower to compress:

 mksquashfs jail src/casper/filesystem.squashfs -b 104857 -comp xz

For Trisquel 2.0 to 3.0 add -nolzma. This option was removed in Trisquel Awen 3.5. The option was to "use ZLIB compression method instead of LZMA", but ZLIB is now the default as shown in the man-pages.

• Update the information of the integrity of the files:

 chmod 644 src/casper/filesystem.squashfs
 printf $(sudo du -sx --block-size=1 jail | cut -f1) > src/casper/filesystem.size
 nano src/README.TXT #if you want to edit your distribution README
 rm src/md5sum.txt
 cd src
 find . -type f -print0 | xargs -0 md5sum > md5sum.txt

• Finally, create a new .iso image (notice the dot at the end of the last line):

 mkisofs -D -r -V "My Trisquel modified version" -cache-inodes \  -J -l -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot \  -boot-load-size 4 -boot-info-table -o ../trisquel-modified.iso .

• ... and prepare the iso to be bootable by removable media other than CD:

 cd ..
 isohybrid trisquel-modified.iso

• If you want, you can also create a md5sum of your file, which is optional. You can use this later to make sure that your distribution hasn't been compromised:

 md5sum "$outfile" > "$outfile".md5

Optional test

• Install qemu:

 aptitude install qemu

• For a 64-bit system:

 qemu-system-x86_64 -boot d -cdrom trisquel-modified.iso -m 512

• For a i386 (486 and 586) system:

 qemu-system-i386 -boot d -cdrom trisquel-modified.iso -m 512

If it runs well, congratulations, you are done! If it doesn't, review your steps or get in touch. To actually make a bootable CD or USB use Xfburn or the USB-installer (usb-creator-gtk.) Please make clear to anyone you distribute your version to that it is not an official Trisquel .iso image. If any non-free software is included, please rename your project and do not use our logo. In the making of this manual, some information was taken from d2 (david /at/ decotigny point fr, [1]) and https://gitlab.trisquel.org/trisquel/makeiso/-/raw/master/makeiso.sh

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remaster_trisquel.sh	18.78 KB