Tiny Core Linux

TinyCore is a nifty linux distro that's extremely small. It's main appeal is the small size and also the ability to save or revert any changes to the system.

PXE Boot

If PXE boot TinyCore, create a boot menu that loads the kernel and core.gz image:

LABEL Core
 	MENU LABEL Core
         kernel /images/core/vmlinuz
         INITRD /images/core/core.gz

The standard image will not have any extensions and will drop you into a shell. To get a GUI, you will need to load Xvesa, wbar, flwm_topside and their dependencies. The simplest way is to provide TinyCore with a NFS share containing these extensions like so:

LABEL Core
 	MENU LABEL Core
         kernel /images/core/vmlinuz
         INITRD /images/core/core.gz nfsmount=10.1.1.1:/tftpboot/images/tinycore

Where /tftpboot/images/tinycore contains:

$ ls /tftpboot/images/tinycore
tce

$ ls /tftpboot/images/tinycore/tce
mydata.tgz onboot.lst optional

When TinyCore boots, the NFS share will be mounted as /mnt/nfs.

Alternatively, if you don't have a NFS server, you can specify a httplist that specifies the web server and the path to a file that contains a list of URIs (on that server) that TinyCore should download and load.

LABEL Core
 	MENU LABEL Core
         kernel /images/core/vmlinuz
         INITRD /images/core/core.gz httplist=pages.cpsc.ucalgary.ca:80/~leo/boot/pxe/linux/data/tinycore/list.txt

The list file contains:

/~leo/boot/pxe/linux/data/tinycore/8.x/libICE.tcz
/~leo/boot/pxe/linux/data/tinycore/8.x/imlib2.tcz
/~leo/boot/pxe/linux/data/tinycore/8.x/libSM.tcz
...

The only drawback to this feature is that the packages are downloaded from the server hosting that list. This means that you won't be able to make TinyCore download packages from an existing mirror.

Since these extensions can get quite large, you can avoid making a copy of the extensions using mod_rewrite. In the case above, I had this .htaccess file in the 8.x directory that forwards package requests to a mirror.

RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule (.*) http://mirror.cpsc.ucalgary.ca/mirror/tinycorelinux/8.x/x86/tcz/$1 [P,L]

Customization

I have made the following changes to /etc/init.d/tc-functions

--- /home/staff/leo/tc-config   2017-04-08 08:40:04.000000000 -0600
+++ /tmp/tc-config      2017-08-18 17:12:14.000000000 -0600
@@ -61,6 +61,7 @@
                                rsyslog=* ) RSYSLOG=${i#*=}; SYSLOG=1 ;;
                                blacklist* ) BLACKLIST="$BLACKLIST ${i#*=}" ;;
                                iso* ) ISOFILE=${i#*=} ;;
+                               postexec*) POSTEXEC=${i#*=} ;;
                        esac
                ;;
                *)
@@ -613,6 +614,13 @@
        [ -z "$NORTC" ] || /etc/init.d/settime.sh &
 fi

+# Post run script
+# Blindly run the script given from postexec=
+if [ -n "$POSTEXEC" ]; then
+       [ -z "$DHCP_RAN" ] && wait4Server $HOST $NOPING
+       wget -O - "$POSTEXEC" | sh
+fi
+
 [ -n "$CRON" ] && /etc/init.d/services/crond start

 /sbin/loadcpufreq 2>/dev/null &

With this modification, you can pass postexec as a kernel argument which then gets executed after all the extensions have loaded, but before the user-side programs start. Eg:

kernel http://${base_url}/linux/data/tinycore/8.x/vmlinuz httplist=pages.cpsc.ucalgary.ca:80/~leo/boot/pxe/linux/data/tinycore/list.txt showapps postexec=http://pages.cpsc.ucalgary.ca/~leo/boot/pxe/linux/data/tinycore/post_install.sh

Miscellaneous

Installing to Hard Drive

The installer can be used to install TinyCore on a hard drive. Get the tc-install package and run it.

Mirrors

The mirror can be selected by editing /opt/tcemirror.

To use CPSC's mirror, edit /opt/tcemirror and replace it with:

http://mirror.cpsc.ucalgary.ca/mirror/tinycorelinux/

Modifying mydata.tgz

If you are running TinyCore on a NFS share, you might not be able to modify the system and then save the changes like you normally would with filetool.sh -b because /mnt/nfs may be read only.

To modify mydata.tgz outside of the TinyCore environment:

# umask 022       # In case you have a weird umask, default to 022.
# mkdir tce       # this dir should be 755 (anything less will kill your tce image)
# cd tce
# tar --numeric-owner -xzpf ../mydata.tgz   # Keep permissions and ownership!
## make your changes
# tar --numeric-owner -czpf ../mydata.tgz *     # Re-create the tarball with permissions

Overwrite the old mydata.tgz on the NFS share and then test the changes on TinyCore by running:

# filetoool.sh -r

Any changes you've made should be visible immediately.

Altering core.gz - Initrd Image

Follow the steps below if you wish to have the system include a set of packages out of the box without needing to load it as extensions.

Extract

Extract the core.gz file.

$ mkdir -p /tmp/tinycore/extract
$ mv core.gz /tmp/tinycore  # where core.gz is the initrd file
$ cd /tmp/tinycore/extract
$ zcat ../core.gz | cpio -i

The extract directory should now contain the contents of the initrd file system.

Adding Additional Packages

Download the .tcz files you want installed from the repository. Store them somewhere (say /tmp/tinycore/packages). Each package is a squashfs filesystem which can be extracted using the unsquashfs utility.

$ cd /tmp/tinycore/extract
$ for i in `ls ../packages/*.tcz` ; do unsquashfs -f -d . $i ; done

If you wish to run something on startup, put it in /opt/bootsync.sh or /opt/bootlocal.sh. /opt/bootsync.sh gets called by /etc/init.d/tc-config. Just note that networking might not be up immediately since the dhcp client runs asynchronously. I got around this by running while true ; do wget -O - http://somewhere.com && break ; done just to verify networking is up.

Remastering

With the changes made to the root file system, you will want to package the directory back up to create the initrd image. To do this, do:

$ cd /tmp/tinycore/extract
$ find | cpio -o -H newc > ../core
$ cd ..
$ gzip core
$ advdef -z4 core.gz # this step is optional, but may save you ~2% of space.