dracut/lsinitrd

#!/bin/bash
# -*- mode: shell-script; indent-tabs-mode: nil; sh-basic-offset: 4; -*-
# ex: ts=8 sw=4 sts=4 et filetype=sh
#
# Copyright 2005-2010 Harald Hoyer <harald@redhat.com>
# Copyright 2005-2010 Red Hat, Inc.  All rights reserved.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

[[ $# -le 2 ]] || { echo "Usage: $(basename $0) [<initramfs file> [<filename>]]" ; exit 1 ; }
image="${1:-/boot/initramfs-$(uname -r).img}"
[[ -f "$image" ]]    || { echo "$image does not exist" ; exit 1 ; }

CAT=zcat
FILE_T=$(file "$image")

if [[ "$FILE_T" =~ ": gzip compressed data" ]]; then
    CAT=zcat
elif [[ "$FILE_T" =~ ": xz compressed data" ]]; then
    CAT=xzcat
elif [[ "$FILE_T" =~ ": XZ compressed data" ]]; then
    CAT=xzcat
elif [[ "$FILE_T" =~ ": data" ]]; then
    CAT=lzcat
fi

if [[ $# -eq 2 ]]; then
    $CAT $image | cpio --extract --verbose --quiet --to-stdout ${2#/} 2>/dev/null
    exit $?
fi

echo "$image: $(du -h $image | awk '{print $1}')"
echo "========================================================================"
$CAT "$image" | cpio --extract --verbose --quiet --to-stdout 'lib/dracut/dracut-*' 2>/dev/null
echo "========================================================================"
$CAT "$image" | cpio --extract --verbose --quiet --list
echo "========================================================================"