Mini Shell

#!/bin/bash --norc
kver=$(uname -r)

boot_dir="/boot"
quiet=0
host_only=0
force=0

error() { echo "$@" >&2; }

usage () {
    [[ $1 = '-n' ]] && cmd=echo || cmd=error

    $cmd "usage: ${0##*/} [--version] [--help] [-v] [-f] [--preload <module>]"
    $cmd "       [--image-version] [--with=<module>]"
    $cmd "       [--nocompress]"
    $cmd "       <initrd-image> <kernel-version>"
    $cmd ""
    $cmd "       (ex: ${0##*/} /boot/initramfs-$kver.img $kver)"

    [[ $1 = '-n' ]] && exit 0
    exit 1
}

# Little helper function for reading args from the commandline.
# it automatically handles -a b and -a=b variants, and returns 1 if
# we need to shift $3.
read_arg() {
    # $1 = arg name
    # $2 = arg value
    # $3 = arg parameter
    param="$1"
    local rematch='^[^=]*=(.*)$' result
    if [[ $2 =~ $rematch ]]; then
        read "$param" <<< "${BASH_REMATCH[1]}"
    else
	for ((i=3; $i <= $#; i++)); do
            # Only read next arg if it not an arg itself.
            if [[ ${@:$i:1} = -* ]];then
		break
            fi
            result="$result ${@:$i:1}"
            # There is no way to shift our callers args, so
            # return "no of args" to indicate they should do it instead.
	done
	read "$1" <<< "$result"
        return $(($i - 3))
    fi
}

# Taken over from SUSE mkinitrd
default_kernel_images() {
    local regex kernel_image kernel_version version_version initrd_image
    local qf='%{NAME}-%{VERSION}-%{RELEASE}\n'

    case "$(uname -m)" in
        s390|s390x)
            regex='image'
            ;;
        ppc|ppc64)
            regex='vmlinux'
            ;;
        i386|x86_64)
            regex='vmlinuz'
            ;;
        arm*)
            regex='[uz]Image'
            ;;
        aarch64)
            regex='Image'
            ;;
        *)  regex='vmlinu.'
            ;;
    esac

    # user mode linux
    if grep -q UML /proc/cpuinfo; then
            regex='linux'
    fi

    kernel_images=""
    initrd_images=""
    for kernel_image in $(ls $boot_dir \
            | sed -ne "\|^$regex\(-[0-9.]\+-[0-9]\+-[a-z0-9]\+$\)\?|p" \
            | grep -v kdump$ ) ; do

        # Note that we cannot check the RPM database here -- this
        # script is itself called from within the binary kernel
        # packages, and rpm does not allow recursive calls.

        [ -L "$boot_dir/$kernel_image" ] && continue
        [ "${kernel_image%%.gz}" != "$kernel_image" ] && continue
        kernel_version=$(/usr/bin/get_kernel_version \
                         $boot_dir/$kernel_image 2> /dev/null)
        initrd_image=$(echo $kernel_image | sed -e "s|${regex}|initrd|")
        if [ "$kernel_image" != "$initrd_image" -a \
             -n "$kernel_version" -a \
             -d "/lib/modules/$kernel_version" ]; then
                kernel_images="$kernel_images $boot_dir/$kernel_image"
                initrd_images="$initrd_images $boot_dir/$initrd_image"
        fi
    done
    for kernel_image in $kernel_images;do
	kernels="$kernels ${kernel_image#*-}"
    done
    for initrd_image in $initrd_images;do
	targets="$targets $initrd_image"
    done
    host_only=1
    force=1
}

while (($# > 0)); do
    case ${1%%=*} in
        --with-usb) read_arg usbmodule "$@" || shift $?
            basicmodules="$basicmodules ${usbmodule:-usb-storage}"
            unset usbmodule;;
        --with-avail) read_arg modname "$@" || shift $?
            basicmodules="$basicmodules $modname";;
        --with) read_arg modname "$@" || shift $?
            basicmodules="$basicmodules $modname";;
        --version)
            echo "mkinitrd: dracut compatibility wrapper"
            exit 0;;
        -v|--verbose) dracut_args="${dracut_args} -v";;
        -f|--force) force=1;;
        --preload) read_arg modname "$@" || shift $?
            basicmodules="$basicmodules $modname";;
        --image-version) img_vers=yes;;
        --rootfs|-d) read_arg rootfs "$@" || shift $?
            dracut_args="${dracut_args} --filesystems $rootfs";;
        --nocompress) dracut_args="$dracut_args --no-compress";;
        --help) usage -n;;
        --builtin) ;;
        --without*) ;;
        --without-usb) ;;
        --fstab*) ;;
        --ifneeded) ;;
        --omit-scsi-modules) ;;
        --omit-ide-modules) ;;
        --omit-raid-modules) ;;
        --omit-lvm-modules) ;;
        --omit-dmraid) ;;
        --allow-missing) ;;
        --net-dev*) ;;
        --noresume) ;;
        --rootdev*) ;;
        --thawdev*) ;;
        --rootopts*) ;;
        --root*) ;;
        --loopdev*) ;;
        --loopfs*) ;;
        --loopopts*) ;;
        --looppath*) ;;
        --dsdt*) ;;
        --bootchart) ;;
	-s) ;;
	--quiet|-q) quiet=1;;
	-b) read_arg boot_dir "$@" || shift $?
	    if [ ! -d $boot_dir ];then
		error "Boot directory $boot_dir does not exist"
		exit 1
	    fi
	    ;;
	-k) # Would be nice to get a list of images here
	    read_arg kernel_images "$@" || shift $?
	    for kernel_image in $kernel_images;do
		kernels="$kernels ${kernel_image#*-}"
	    done
	    host_only=1
	    force=1
	    ;;
	-i) read_arg initrd_images "$@" || shift $?
	    for initrd_image in $initrd_images;do
		targets="$targets $boot_dir/$initrd_image"
	    done
	    ;;
        *)  if [[ ! $targets ]]; then
            targets=$1
            elif [[ ! $kernels ]]; then
            kernels=$1
            else
            usage
            fi;;
    esac
    shift
done

[[ $targets && $kernels ]] || default_kernel_images
[[ $targets && $kernels ]] || (error "No kernel found in $boot_dir" && usage)

# We can have several targets/kernels, transform the list to an array
targets=( $targets )
[[ $kernels ]] && kernels=( $kernels )

[[ $host_only == 1 ]] && dracut_args="${dracut_args} -H"
[[ $force == 1 ]]     && dracut_args="${dracut_args} -f"

echo "Creating: target|kernel|dracut args|basicmodules "
for ((i=0 ; $i<${#targets[@]} ; i++)); do

    if [[ $img_vers ]];then
	target="${targets[$i]}-${kernels[$i]}"
    else
	target="${targets[$i]}"
    fi
    kernel="${kernels[$i]}"

    # Duplicate code: No way found how to redirect output based on $quiet
    if [[ $quiet == 1 ]];then
	echo "$target|$kernel|$dracut_args|$basicmodules"
	if [[ $basicmodules ]]; then
            dracut $dracut_args --add-drivers "$basicmodules" "$target" \
		"$kernel" &>/dev/null
	else
            dracut $dracut_args "$target" "$kernel" &>/dev/null
	fi
    else
	if [[ $basicmodules ]]; then
            dracut $dracut_args --add-drivers "$basicmodules" "$target" \
		"$kernel"
	else
            dracut $dracut_args "$target" "$kernel"
	fi
    fi
done