Simple script to get battery charge and time remaining...

Question

Here's something I threw together last night, to report on the battery at the command line.  It uses /proc/acpi/battery.  My battery is C11F, just substitude your own.
It takes (remaining capacity) / (design capacity) to get the percent left, and it takes the (discharge rate) / (remaining capacity) to get approximate life.  If the rate is zero (which mine reports as when plugged in) it says the battery is charging.
I don't know if this will work for other people, or if different batteries give different times of information to ACPI.
#!/bin/bash
current=`grep remaining /proc/acpi/battery/C11F/state | tr -d A-z | tr -d " " | tr -d :`
total=`grep "design capacity:" /proc/acpi/battery/C11F/info | tr -d A-z | tr -d " " | tr -d :`
rate=`grep "present rate:" /proc/acpi/battery/C11F/state | tr -d A-z | tr -d " " | tr -d :`
percent=`bc << EOF
100.0 * $current / $total
EOF
`
if [ $rate -eq 0 ]; then
echo $percent'%, charging'
else
hours=`bc << EOF
(1.0*$current) / (1.0*$rate)
EOF
`
minutes=`bc << EOF
60.0 * $current / $rate - $hours * 60
EOF
`
echo $percent'%, '$hours':'$minutes
fi

Answer 1

zen_guerrilla wrote:You can also try the 'acpi' pkg, which does exactly the same thing .
Considering the acpi package is only dated a few days ago, I don't feel too bad about not knowing about it.
BTW, here's an update I did to my script.  This one prints minutes less than 10 correctly (1:02 vs 1:2), as well as finding batteries with other names, and printing the CPU speed (nice if you have speed stepping turned on).  It rounds to the nearest 100MHz, which is easy to remove if you don't like it.
#!/bin/bash
speed=`grep "cpu MHz" /proc/cpuinfo | tr -d A-z | tr -d " " | tr -d :`
current=`grep remaining /proc/acpi/battery/*/state | tr -d A-z | tr -d " " | tr -d :`
total=`grep "design capacity:" /proc/acpi/battery/*/info | tr -d A-z | tr -d " " | tr -d :`
rate=`grep "present rate:" /proc/acpi/battery/*/state | tr -d A-z | tr -d " " | tr -d :`
int_speed=`bc << EOF
($speed+50) / 100 * 100
EOF
`
percent=`bc << EOF
100.0 * $current / $total
EOF
`
if [ $rate -eq 0 ]; then
echo $int_speed'MHz, '$percent'%, charging'
else
hours=`bc << EOF
(1.0*$current) / (1.0*$rate)
EOF
`
minutes=`bc << EOF
60.0 * $current / $rate - $hours * 60
EOF
`
if [ $minutes -lt 10 ]; then
echo $int_speed'MHz, '$percent'%, '$hours':0'$minutes
else
echo $int_speed'MHz, '$percent'%, '$hours':'$minutes
fi
fi