is there any command that comes with a slackware installation that can display the battery life?

apm package will do, if you installed.

We need to know more about your laptop, but assuming a newer model you should have installed the kernel with ACPI support. Check the contents of /proc/acpi/ for CPU, temp and battery info. You can just cat the appropiate file. If that directory doesn't exist than you probably didn't install a kernel that supports ACPI.

Dennisk

Gkrellm displays battery level.

gkrellm can only display the battery level if there is a command to do it but there is no command on my system that displays the battery life. Also /proc/acpi doesn't exist. Im running the default 2.4.31 kernel that came with slackware. I've tried upgrading but it always f**ks up.

The default kernel doesn't support ACPI and if you have a laptop make in the last five years or so it probably doesn't support APM. Looking at your BIOS power management screen should give you a hint. Without ACPI you have no power managment and no ability to read battery levels. The solution is to install an ACPI kernel.

Dennisk

Give it a go upgrading the kernel again dude... What kind of laptop do you have?
Get your hands on a simple kernel upgrade guide on google and do a basic follow of the steps they list... The number one rule in your case is to make sure you 'build up on the existing .config file that was used for your 2.4.31 kernel'.
It will be found in /usr/src/linux
use this file when creating your new kernel.... In other words you will start with the same config that you currently have and you can simply add in support for ACPI and compile...

Its worth it.. you get all sorts of cool things (like CPU frequency changing) - where you can manually set the freq to a Mhz you choose or let the system adjust it for you) - Is great for laptops/saving battery life/ having a machine tht runs well when you need it to..