Build a live usb disk from rootfs.tgz

auto_sys_inst.sh

#!/bin/bash -
###############################################################################
# FILENAME:
#     auto_sys_inst.sh
#
# DESCRIPTION:
#     Build a live usb disk from rootfs.tgz
#
# REVISION(MM/DD/YYYY):
#     11/22/2011  jia.sui([email protected])
#     - Initial version
###############################################################################

if [[ $# -ne 2 ]]; then
    echo "Usage: $0 {dev_node} {rootfs}"
    echo "      dev_node: /dev/sda"
    echo "      rootfs:  rootfs.tgz under current path."
    echo "Example: $0 /dev/sda rootfs.tgz"
    exit 2
fi

dev_node=$1
rootfs=$2

#create partition
echo "Please delete the old partitions, and create a new partition on usb disk."
fdisk $dev_node
if [[ $? -ne 0 ]]; then
    echo "Create partition on $dev_node failed."
    exit 2
fi

#if mounted ,umount first partition of $dev_node
mount | grep ${dev_node}1
if [[ $? -eq 0 ]]; then
    umount ${dev_node}1
fi

#make file system
mkfs.ext3 ${dev_node}1
if [[ $? -ne 0 ]]; then
    echo "Format ${dev_node}1 as ext3 failed."
    exit 2
fi

#mount first partition of $dev_node
if [[ ! -d /mnt/tmp ]]; then
    mkdir /mnt/tmp
fi

mount ${dev_node}1 /mnt/tmp

#install grub
grub-install --root-directory=/mnt/tmp ${dev_node}1 --no-floppy

#extract rootfs.tgz
rootfs_full=`pwd`$rootfs
cd /mnt/tmp
tar zxvf $rootfs_full
cd `dirname $rootfs_full`

#Change partition label
e2label ${dev_node}1

#Disable selinux
if [[ -e /etc/selinux/config ]]; then
    sed -r "s/^SELINUX=.*$/SELINUX=disabled/g" "/mnt/tmp/etc/selinux/config" > "/mnt/tmp/etc/selinux/config"
fi

#umount first partition of $dev_node and remove temp dir.
umount ${dev_node}1
rmdir /mnt/tmp

exit 0