unset var

echo ${var#}
echo ${var##}
echo ${var#*}
echo ${var##*}
echo ${var%}
echo ${var%%}
echo ${var%*}
echo ${var%%*}

var=

echo ${var#}
echo ${var##}
echo ${var#*}
echo ${var##*}
echo ${var%}
echo ${var%%}
echo ${var%*}
echo ${var%%*}

var=ababcdcd

echo ${var#ab}
echo ${var##ab}
echo ${var#a*b}
echo ${var##a*b}
echo ${var#?}
echo ${var##?}
echo ${var#*}
echo ${var##*}

echo ${var%cd}
echo ${var%%cd}
echo ${var%c*d}
echo ${var%%c*d}
echo ${var%?}
echo ${var%%?}
echo ${var%*}
echo ${var%%*}

echo end