for a in {a..h}{1..8};do b+=($a);done while read s||((${#s}));do m=() ((p=8*(26#${s%?}-10)+${s#?}-1)) for c in -6 10 17 15 6 -10 -17 -15;do ((v=p%8-(p+c)%8)) ((p+c>0&&${v#-}<3))&&m+=(${b[p+c]}) done echo ${m[*]} done