Shell Programming and Scripting

So, I know this can be done but my awk and sed wizardry is not up to snuff for the job. Basically, I have tons and tons of Macbooks at my work and I am trying to grab the current percentage of the battery power on each client.

If I use the system_profiler SPPowerDataType command it prints off the current specs of all power management. One spec is the current charge of the battery in mAh, and one is the total capacity.

So, I would like to grep | awk | or sed out this info and then have it do simple division then convert the answer into readable percentage.

So like if I pull out the string of the current charge and it is at 1020 mAh, and I know that the total capacity of the battery is 5242 mAh. I could grab both of those strings but how to I make those form a number in percentage that is human readable?

Thanks a ton for any help in advance.

EDIT

Guess I should give some example code...

Code:

system_profiler SPPowerDataType | grep "Charging status" | awk '{ print 4}'

This returns the numerical number of how much charge, and I would need to grab the total capacity and the divide them or whatever to output a percentage.

Sample code to give you a percentage (assumes you have obtained the values into the CURRENT_CHARGE and BATTERY_CAPACITY variables, e.g.:

Code:

CURRENT_CHARGE=`system_profiler SPPowerDataType | grep "Charging status" | awk '{ print 4}'`

Sample code:

Code:

CURRENT_CHARGE=1020
BATTERY_CAPACITY=5242

PERCENT_CHARGED=`echo "scale=3; ${CURRENT_CHARGE} / ${BATTERY_CAPACITY} * 100" | bc`
echo "PERCENT_CHARGED = ${PERCENT_CHARGED}%"

Running a script containing the above code produces the output:

Code:

$ ./percent_calc_script.sh
PERCENT_CHARGED = 19.400%

The only thing I am wondering is if every battery has the same maximum capacity. I also get a syntax error when trying your method. I know that I could do A / B *100 to get the percentage but I was hoping to do it in a one liner with awk or sed....

Thanks again for your input though it is definitely helpful.

Code:

# eval $(system_profiler SPPowerDataType | awk -F= '/CURRENT_CHARGE/{x=$NF}/BATTERY_CAPACITY/{printf "PERCENT_CHARGED=%.2f%c",(x/($NF/100)),"%"}')
# echo $PERCENT_CHARGED
19.46%

I can't get this to actually work, I am on 10.5.7...

It returns a blank line for the command. I tried it with just the command but have not put it in a script.