#!/bin/sh
# theres probably a way easier way to do this but I want it to be pretty much unix-like universal
# this should run on Linux, FreeBSD, OpenBSD, NetBSD, macOS and Solaris
# basically everything that has df -P
df -P | awk '
	function convert(n) {
		split("K M G T P", unit, " ")
		i = 1
		while (n >= 1024 && i < length(unit)) {
			n = n / 1024
			i++
		}
		return sprintf("%.1f%s", n, unit[i])
	}
	$6=="/" || $6=="/home" || $6=="/tmp" || $6 ~ /^\/usr/ || $6=="/var" {
		used += $3
		total += $2
	}
	
	END {
    	print convert(used) "/" convert(total)
	}
'