mnt-initrd

#!/bin/bash

set -e

if [[ "$OSTYPE" != linux* ]]; then
  echo "Not on a Linux box; aborting." >&2
  exit 1
fi

if [[ `id -u` != 0 ]]; then
  echo "Not root; aborting." >&2
  exit 1
fi

if [[ $# != 1 ]]; then
  echo "Usage: $0 <initrd image>"
  echo "       $0 <floppy image>"
  exit 1
fi

if ! [[ -f $1 ]]; then
  echo "$1 isn't a valid file; aborting." >&2
  exit 1
fi

case "`file $1`" in
  *SYSLINUX*)
    echo "$1 is a floppy image" # e.g. bootnet.img
    floppy=$1
    floppy_base=${1##*/}
    mnt-image $floppy
    img=mnt:$floppy_base/initrd.img
    imgbase=initrd.img
    ;;
  *)
    img=$1
    imgbase=${img##*/}
    ;;
esac

tmpimg=/tmp/$imgbase
cp $img $tmpimg.gz
gunzip $tmpimg.gz

case "`file $tmpimg`" in
  *cpio*)
    echo "$tmpimg is a cpio archive"
    mv $tmpimg $tmpimg.cpio
    mkdir $tmpimg
    cd $tmpimg
    cpio -idv < $tmpimg.cpio
    rm $tmpimg.cpio
    echo "$img unpacked into $tmpimg"
    exit 0
    ;;
esac

mnt-image $tmpimg