-dnl Make sure file really was compressd.
-AT_CHECK([dd if=com.sav bs=1 skip=72 count=4 2> /dev/null | od | sed '1q' > com.txt])
-dnl Allow big- or little-endian format.
+dnl Make sure file really was compressd, allowing big- or little-endian format.
+AT_CHECK([dd if=com.sav bs=1 skip=72 count=4 2> /dev/null > com.sav.subset])
+od com.sav.subset