I needed a simple script to parse out the Battery Percentage from system call acpi for my conky display on my desktop. Keep it simple. :)
MODIFIED CODE:
*I left out the word 'Battery' intentionally because it is displayed in my conky by default and with another color. The script does what is supposed to do only, get the Percentage and return that only.
#!/usr/bin/perl

print '',( `acpi` =~ /(\d+)%/ )[ 0 ] // '??', "%";

[download]
ORIGINAL CODE - Doesn't include last 0 for 100%. Thanks to jwkrahn for the simpler and more precise code ^^ above 
#!/usr/bin/perl
#battery.pl

use strict;
use warnings;
use 5.012;

my $battery_charge;

$battery_charge = `acpi`;

if($battery_charge =~ /\d{2}%/ )
{

        print "Battery: $&\n";
}

[download]
Silence is golden, but Duct Tape is silver x)

Replies are listed 'Best First'.
Re: Laptop Battery Percentage
by jwkrahn (Abbot) on Aug 01, 2011 at 04:55 UTC

    If the charge is at 100% you are only picking up the last two zeros.

    Simple would be: 

    #!/usr/bin/perl
print 'Battery: ', ( `acpi` =~ /(\d+)%/ )[ 0 ] // '??';

    [download]
[reply]
[d/l]
      I will have to try that out when I get to my laptop tonight :) Thanks for the reply.
      Silence is golden, but Duct Tape is silver x)
[reply]
      I actually liked this reply the best, and it works very good...going to EDIT it now. Thanks for the help jwkrahn
      U-U-D-D-L-R-L-R-A-B->START
[reply]
Re: Laptop Battery Percentage
by zentara (Cardinal) on Aug 01, 2011 at 13:18 UTC
    I don't have the acpi program on my computer, but on linux, with the latest kernel, you can directly read the battery state from

    /proc/acpi/battery/BAT1/state

    which yields when reading 

    present:                 yes
capacity state:          ok
charging state:          charged
present rate:            65535 mA
remaining capacity:      4261 mAh
present voltage:         12209 mV

    [download]
    I'm not really a human, but I play one on earth.
    Old Perl Programmer Haiku ................... flash japh
[reply]
[d/l]

      the state file is kinda static, as in it shows the current state, from which one cannot deduce the percentage.

      The info file is much more informative:

      $ cat /proc/acpi/battery/BAT0/info
present:                 yes
design capacity:         5144 mAh
last full capacity:      5144 mAh
battery technology:      rechargeable
design voltage:          10800 mV
design capacity warning: 200 mAh
design capacity low:     100 mAh
cycle count:              0
capacity granularity 1:  100 mAh
capacity granularity 2:  100 mAh
model number:            Primary
serial number:           49233 2011/02/25
battery type:            LIon
OEM info:                Hewlett-Packard

      [download]

      Combining the two gets you to:

      $ cat /proc/acpi/battery/*/* | grep capacity:
design capacity:         5144 mAh
last full capacity:      5144 mAh
remaining capacity:      5144 mAh
$

      [download]

      Or in perl:

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

      [download]

      Enjoy, Have FUN! H.Merijn
[reply]
[d/l]
[select]

        I use this code in gnu screen's statusbar: 

        backtick 1 1 1 sh -c 'perl -ne "/^(la|re|st)[^:]+:\s+(\S+)\s/and \$h{\
+$1}=\$2}{\$h{st}=~s/of.*/-/;\$h{st}=~s/on.*/+/;printfq(%.0f%%%s),\$h{
+re}*100/\$h{la},\$h{st}" /proc/acpi/battery/BAT0/* /proc/acpi/ac_adap
+ter/ACAD/state'

        [download]
[reply]
[d/l]
        But what if you have two batteries? Some laptops allow that. You will have multiple lines.
        Information doesn't want to be free. It wants to be feline.
[reply]

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