Uptime

how to calculate uptime in days or hours?

1. get last reboot timestamp with

lastRebootTimestamp=$(sysctl kern.boottime | awk -F'[= |,]' '{print $6}')

2. get now timestamp with

nowTimestamp=$(date +%s)

3. calculate the difference

upTimestamp=$((nowTimestamp-lastRebootTimestamp))

4. calculate days

uptimeDays=$((upTimestamp/(24*60*60)))

5. calculate hours

uptimeHours=$((upTimestamp/(60*60)))