$ perl -MDP -e'while(<>){/^(.*)\s+capacity:\s*((\d+).*)/ and$i{$1}=[$2,$3]}print"$_: $i{$_}[0], "for keys%i;printf"%5.1f%%\n",100*$i{remaining}[1]/$i{design}[1]' /proc/acpi/battery/*/*
remaining: 5144 mAh, design: 5144 mAh, last full: 5144 mAh, 100.0%