small script to create an iso "dd-able" to an usb key from an existing iso

rebuild-iso.sh

#!/bin/sh

MOUNT="false"
ISOHDPFX="M+2QkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJAz7fqO1bwAfPv8ZjHbZjHJZlNmUQZXjt2O\nxVK+AHy/AAa5AAHzpepLBgAAUrRBu6pVMckw9vnNE3IWgftVqnUQg+EBdAtmxwbxBrRC6xXrAFpR\ntAjNE4PhP1tRD7bGQFD34VNSULsAfLkEAGahsAfoRAAPgoAAZkCAxwLi8maBPkB8+8B4cHUJ+rzs\ne+pEfAAA6IMAaXNvbGludXguYmluIG1pc3Npbmcgb3IgY29ycnVwdC4NCmZgZjHSZgMG+HtmExb8\ne2ZSZlAGU2oBahCJ5mb3Nuh7wOQGiOGIxZL2Nu57iMYI4UG4AQKKFvJ7zRONZBBmYcPoHgBPcGVy\nYXRpbmcgc3lzdGVtIGxvYWQgZXJyb3IuDQperLQOij5iBLMHzRA8CnXxzRj06/0AAAAAAAAAAAAA\nAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\nAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"

help(){
  echo "usage: `basename $0` -i <input iso> -o <output iso> [-m]"
  echo ""
  echo "Recreate a 'dd able' iso from an existing iso:"
  echo ""
  echo " -i <input iso>: path to the input iso"
  echo " -o <output iso>: path to the output iso"
  echo " -m: use mount instead of 7z to extract iso,"
  echo "     more reliable, but requires root permission"
  echo ""
  exit 1
}

check_cmd(){
    cmd=$1
    type $cmd >/dev/null 2>&1
    ret=$?
    if [ $ret -ne 0 ]
    then
        echo "you need $cmd to be installed"
        exit 1
    fi
}

clean(){
    if [ -d "$TMPDIR" ]
    then
        rm -rf "$TMPDIR"
    fi

    if [ -d "$TMPDIR" ]
    then
        rm -rf "$TMPDIRMOUNT"
    fi
}



while getopts ":hi:o:m" opt; do
  case $opt in

    h) 
        help
        ;;
    i)
        IN="$OPTARG"
        ;;
    o)
        OUT="$OPTARG"
        ;;
    m)
        MOUNT="true"
        ;;

    \?)
        echo "Invalid option: -$OPTARG" >&2
        help
        exit 1
        ;;
    :)
      echo "Option -$OPTARG requires an argument." >&2
        help
        exit 1
        ;;
  esac
done

if [ -z "$IN" ] || [ -z "$OUT" ]
then
    echo "-i and -o are mandatory"
    echo ""
    help
    exit 1
fi

check_cmd xorriso

if [ "$MOUNT" = "true" ]
then
    if ! [ "`whoami`" = "root" ]
    then
        echo "with '-m' flag, `basename $0` must be launched as root"
        exit 1
    fi
else
    check_cmd 7z
fi

trap clean HUP INT TERM

TMPDIR=`mktemp -d`
TMPDIRMOUNT=`mktemp -d`

if [ "$MOUNT" = "true" ]
then
    mount $IN $TMPDIRMOUNT
    cp -rp $TMPDIRMOUNT/* ${TMPDIR}
    umount $TMPDIRMOUNT
else
    7z x -tiso  $IN -o${TMPDIR}
    find ${TMPDIR}/ -depth -exec rename 's/(.*)\/([^\/]*)/$1\/\L$2/' {} \;
fi

printf $ISOHDPFX | base64 -d >${TMPDIR}/isohdpfx.bin

BOOT_CAT=`find ${TMPDIR}/ -name 'boot.cat' |sed "s%${TMPDIR}/*%%"`
ISOLINUX_BIN=`find ${TMPDIR}/ -name 'isolinux.bin' |sed "s%${TMPDIR}/*%%"`

xorriso -as mkisofs \
    -iso-level 3 \
    -full-iso9660-filenames \
    -volid "CustomISO" \
    -preparer "prepared by rebuild-iso" \
    -eltorito-boot $ISOLINUX_BIN \
    -eltorito-catalog $BOOT_CAT \
    -isohybrid-mbr $TMPDIR/isohdpfx.bin \
    -no-emul-boot -boot-load-size 4 -boot-info-table \
    -output "$OUT" \
    "$TMPDIR/"

clean