HOWTO: add battery status to bash prompt

[dkeg]

If you use a laptop with a battery and you tend to forget to plug in, this may be for you.
Add battery status to your prompt. there are more than one way of course, but this is how I'm doing it for now.

create script. I have a directory called scripts, but could also place in ~/bin

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#! /bin/bash
cat /sys/class/power_supply/BAT0/capacity

of course make chmod +x it. and in .bashrc w/in prompt code

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\$(/path/to/script.sh)

oblig scrot

[dkeg]

update to the battery meter script to add to your prompt. Took something I found online and did a re-write. Name it and call it from your .bashrc as described above, or write as a function directly in your .bashrc.

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#! /bin/bash

# battery status script

BATTERY=/sys/class/power_supply/BAT0

CAPACITY=`cat $BATTERY/capacity`
STATE=`cat $BATTERY/status`

NON='\033[00m'
BLD='\033[01m'
RED='\033[01;31m'
GRN='\033[01;32m'
YEL='\033[01;33m'

COLOR="$RED"

case "${STATE}" in
   'Full')
   STATE="$BLD*$NON"
   ;;
   'Charging')
   STATE="$BLD+$NON"
   ;;
   'Discharging')
   STATE="$BLD-$NON"
   ;;
esac

# color code capacity 
if [ "$CAPACITY" -gt "99" ]
then
   CHARGE=100
fi

if [ "$CAPACITY" -gt "15" ]
then
   COLOR="$YEL"
fi
if [ "$CAPACITY" -gt "30" ]
then
   COLOR="$GRN"
fi

echo -e "${COLOR}${CAPACITY}${NON}${STATE}"

# end

EDIT - fixed a couple of errors. Fixed the CHARGED variable and 'Charged' to 'Full' in the case statement.
EDIT 2 - more clean up, less bloat :)

place in .bashrc prompt code

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PS1="\[\033[0;37m\]\][\$(/path/to/script/battstat2.sh)\033[0;37m\]]-[\[\033[0;31m\]\[\A\[\033[0;37m\]]-[\[\033[0;32m\]\w\[\033[0;37m\]]\n\[\033[0;37m\]\342\224\224\342\224\200\342\224\200\342\224\200\342\224\200\342\225\274 \[\033[0m\]"

charging

discharging

[machinebacon]

We could add [used RAM] and [CPU] to it and make conky turn yellow :)

[dkeg]

* fixed a couple mistakes up there ^*

Come on guys, now you're just getting ridiculous :D

But I always space out and forget how low my battery is, that is why I did this little project.

[dkeg]

Taken from the bash prompt thread

http://www.linuxbbq.org/bbs/viewtopic.php?f=4&t=648

[machinebacon]

bonus: memstat.sh - updates for every newly opened term, else can be piped to dzen2 or whatever where.

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#!/bin/bash
hw_mem=0
free_mem=0
human=1024

mem_info=$(</proc/meminfo)
                mem_info=$(echo $(echo $(mem_info=${mem_info// /}; echo ${mem_info//kB/})))
                for m in $mem_info; do
                        if [[ ${m//:*} = MemTotal ]]; then
                                memtotal=${m//*:}
                        fi

                        if [[ ${m//:*} = MemFree ]]; then
                                memfree=${m//*:}
                        fi

                        if [[ ${m//:*} = Buffers ]]; then
                                membuffer=${m//*:}
                        fi

                        if [[ ${m//:*} = Cached ]]; then
                                memcached=${m//*:}
                        fi
                done

usedmem="$(((($memtotal - $memfree) - $membuffer - $memcached) / $human))"
totalmem="$(($memtotal / $human))"

echo "$usedmem"

[xaos52]

My version of 'memstat':- using associative array - the script begs for an associative array

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#!/bin/bash
human=1024
declare -A meminfo

# split the lines from /proc/meminfo in 2 fields using the : as delimeter
meminfo_split () {
    cat /proc/meminfo | awk '
BEGIN { FS=":" }
{ label=$1; value=$2; print label,value }
' 
}

# read into an associative array after 'massaging' the values
while read -r _tag _value; do
    _value=${_value//kB/}
    _value=${_value// /}
    meminfo["$_tag"]="$_value"
done < <(meminfo_split)

# do your calculations
printf '%d Mb\n' $(( ( ${meminfo['MemTotal']} - ${meminfo['MemFree']} - ${meminfo['Buffers']} - ${meminfo['Cached']} ) / $human ))

exit 0

It is slightly faster than yours on my system, and you have all the /proc/meminfo variables available in the script to do all the calcultaions you want.
Better readable too, in my opinion.

Added to my bash_scripts repo on github

[machinebacon]

^ Mine is not mine, it is stolen from screenfetch :)

[xaos52]

Mine will make a better impression on bash script writers, I am sure :)

[machinebacon]

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└────╼ time memstat
565 Mb

real	0m0.031s
user	0m0.006s
sys	0m0.006s
[100]─[22:33]─[~]
└────╼ time memstat.sh
565

real	0m0.048s
user	0m0.010s
sys	0m0.005s
[100]─[23:40]─[~]
└────╼ time free -h | awk 'NR==3 { print $3 }'
602M

real	0m0.010s
user	0m0.002s
sys	0m0.001s

"slightly faster" - Doctor, you exaggerate:))

I'll replace it, thanks for the addition.
Edit: Pidsley wins the decruftification award.

[pidsley]

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free -h | awk 'NR==3 { print $3 }'

[machinebacon]

^ :tongue-in-cheek: but Bash-lovers won't find it fancy ;)

Of course that's the sexiest one.

[dkeg]

^^Simplistically beautiful. And definitely bloat free.

[wuxmedia]

I bloated the original script, as found on pony muncher;
If there's no battery present stops the spam.
no quite sure how it would fit into the updated version, over 10 lines and I get dizzy 8)

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#!/bin/bash
# test if /sys/class/power_supply/BAT0/capacity exists, avoiding console spam on desktops

if test -e /sys/class/power_supply/BAT0/capacity; then
  cat /sys/class/power_supply/BAT0/capacitycat /sys/class/power_supply/BAT0/capacity >&2
else
  exit 1
fi

haven't tested it on a lappy yet.

[pidsley]

If there's no battery present stops the spam.

Thank you from those of us with no batteries.

[wuxmedia]

You're welcome.
AND I learnt a tiny bit of bash, baby steps wux... 8)
still not sure if it will work with a battery.