When the shell tests for rootfs type I was seeing "[[: not found".  I
use echo and egrep to test for the xz rootfs type to work around this
error.

Signed-off-by: Seth Bollinger <seth.boll@gmail.com>
---
  classes/sdcard_image-rpi.bbclass |    2 +-
  1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/classes/sdcard_image-rpi.bbclass 
b/classes/sdcard_image-rpi.bbclass
index 421f561..7fe7c35 100644
--- a/classes/sdcard_image-rpi.bbclass
+++ b/classes/sdcard_image-rpi.bbclass
@@ -99,7 +99,7 @@ IMAGE_CMD_rpi-sdimg () {
      # Burn Partitions
      dd if=${WORKDIR}/boot.img of=${SDIMG} conv=notrunc seek=1 
bs=$(expr ${IMAGE_ROOTFS_ALIGNMENT} \* 1024) && sync && sync
      # If SDIMG_ROOTFS_TYPE is a .xz file use xzcat
-    if [[ "$SDIMG_ROOTFS_TYPE" == *.xz ]]
+    if echo "${SDIMG_ROOTFS_TYPE}" | egrep -q "*\.xz"
      then
          xzcat ${SDIMG_ROOTFS} | dd of=${SDIMG} conv=notrunc seek=1 
bs=$(expr 1024 \* ${BOOT_SPACE_ALIGNED} + ${IMAGE_ROOTFS_ALIGNMENT} \* 
1024) && sync && sync
      else
-- 
1.7.2.5