I wanted to tweak my bash battery monitor so that it displayed an updated value everytime a sub-shell returned. Coloring code adds cruft, so I removed it for this example. Here is what works for me:
(Add to .bashrc, PS1 section):
if [[ ( -e $HOME/.battery_check ) ]]; then
PS1="[\$($HOME/.battery_check)] ${debian_chroot:+($debian_chroot)}\u@\h:\w\$ "
else
PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
fi
(create an executable file $HOME/.battery_check with the following)
#!/bin/bash
BATTERY=/proc/acpi/battery/BAT0
REM_CAP=`grep "^remaining capacity" $BATTERY/state | awk '{ print $3 }'`
FULL_CAP=`grep "^last full capacity" $BATTERY/info | awk '{ print $4 }'`
BATSTATE=`grep "^charging state" $BATTERY/state | awk '{ print $3 }'`
CHARGE=`echo $(( $REM_CAP * 100 / $FULL_CAP ))`
case "${BATSTATE}" in
'charged')
BATSTT="$BLD="
;;
'charging')
BATSTT="$BLD⚡"
;;
'discharging')
BATSTT="$BLD-"
;;
esac
echo -e "${CHARGE}${BATSTT}"
