Alain Kelder is a Giant Dork

Determine system age in a shell script

One way is to grab the number of seconds from /proc/uptime, then discard everything after the decimal (since Bash can compare integers but not floating point numbers).

So instead of this:

cat /proc/uptime

400149.27 3016453.79

We get this:

sed 's/\..*//' /proc/uptime

400149

In this example, my age threshold is 1 day (86400 seconds):

if [ $(sed 's/\..*//' /proc/uptime) -gt 86400 ]; then
  echo "I'm old"
  status=old
else
  echo "I'm new"
  status=new
fi