Something similar to `uptime -p` but for busybox

pretty-uptime.sh

#!/bin/sh
# pretty-print system uptime

# get uptime and idle
read -r u _ < /proc/uptime
u=${u%.*}

# function to calculate and print time period
print_period() {
        period_seconds="$1"
        period_label="$2"
        [ "${u}" -lt "${period_seconds}" ] && return
        period_value=$(( u / period_seconds ))
        u=$(( u - period_value * period_seconds ))
        [ "${period_value}" -gt "1" ] && period_label="${period_label}s"
        printf "%d %s " "${period_value}" "${period_label}"
}

# call the function for each time period
print_period 31557600 "year"
print_period 2629800 "month"
print_period 604800 "week"
print_period 86400 "day"
print_period 3600 "hour"
print_period 60 "minute"
print_period 1 "second"

# go to the next line
printf "\n"