RedHat VM last patched duration in days

On RedHat systems, rpm tracks the install timestamp of every package, which lets you calculate when the most recent patch was applied. I use this in compliance checks to flag VMs that haven’t been patched in too long. The date arithmetic in the last block converts seconds since epoch to days.

• current date in numeric

$ date +%s

• get all installed patches with date and name in human redable form

$ rpm -qa --queryformat '%{installtime} %{installtime:date} %{name}\n'

• get all installed patches with date and name in human redable form, sort it using installtime and return top record

$ rpm -qa --queryformat '%{installtime} %{installtime:date} %{name}\n' | sort | tail -n 1

• get all installed patches installtime only, sort it using installtime and return top record

$ rpm -qa --queryformat '%{installtime}\n' | sort | tail -n 1

• putting it all together and substracting dates

$ current_date=$(date +%s)
$ last_path_installed_date=$(rpm -qa --queryformat '%{installtime}\n' | sort | tail -n 1)
$ let last_patched=($current_date - $last_path_installed_date)/86400
$ echo $last_patched