get system boot time in milliseconds in ruby

To get the system boot time in milliseconds in Ruby, we can use the uptime command and parse its output. Here's an example code snippet:

main.rb
def system_boot_time
  output = `uptime`
  match_data = /up (.+),/.match(output)
  uptime_str = match_data[1]
  uptime_parts = uptime_str.split(":")
  hours, mins, secs = uptime_parts.map(&:to_i)
  uptime = hours * 3600 + mins * 60 + secs
  boot_time = Time.now.to_i - uptime
  boot_time * 1000
end
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This method uses the uptime command to get the system uptime, parse the output to get the uptime string, convert it to seconds, and then subtract it from the current time to get the system boot time in seconds. Finally, it multiplies the result with 1000 to get it in milliseconds.