seconds: CLI for quick time interval calculation

Here’s a quick script I swear I’ve written before but couldn’t find. If given a string as an argument, it converts it to seconds, and if given just a series of numbers, it converts the number to a human-readable string.

I needed this today when setting update intervals for Sparkle, and it’s something I’ve run into in the past. I usually pull up a calculator, which is annoying. There’s probably a simple Unix way to do it that I’ll hear about in the comments, which is ok, I still had fun writing it.

Since this is mostly likely to be of use to programmers, I won’t bother detailing how to turn it into an executable script. You got this.

Convert strings to seconds

Arguments are numbers followed by a timespan. It works on shorthand (w = week, day = d, hours = h, minutes = m, seconds = s), but will convert most strings to this format automatically, e.g. “2 days, 3 hours, and 30 min” is the same as “2d3h”. As long as the format is a number followed by strings that start with w, d, h, m, or s, it’ll figure it out.

$ seconds 3d2h
=> 266400
$ seconds 2 days, and 3 hours
=> 183600

Convert seconds to a human-readable string

$ seconds 266400
=> 3 days, 2 hours

Here’s the script. Do with it what you will.

#!/usr/bin/env ruby
# seconds, a CLI for interval conversion by Brett Terpstra 2017
# Free for use by anyone, anywhere, at any time
## convert days, hours, and minutes to seconds
# Arguments are numbers followed by a timespan
# (w = week day = d, hours = h, minutes = m, seconds = s)
# e.g. 2 days and 3 hours = "2d3h"
# unrecognized characters don't matter, so also "2 days, and 3 hours"
# $ seconds 2 days, and 3 hours
# => 183600
## convert seconds to days, hours, and minutes
# $ seconds 183600
# => 2 days, 3 hours

require 'bigdecimal'

def help(do_exit=false)
  app = File.basename(__FILE__)
  usage = ["#{app}: convert days, hours, and minutes to seconds"]
  usage.push("Usage: #{app} [Xw[Xd[Xh[Xm]]]] | [seconds]")
  usage.push("#{app} 5d2h3m => 439380")
  usage.push("#{app} 4d => 345600")
  usage.push("Or convert seconds to time units: #{app} 1125093 => 13 days, 31 minutes, 33 seconds")
  if do_exit
    code = do_exit.to_i rescue 0
    Process.exit code

class String
  def plural
    num, unit = self.split(/ /)
    if num.to_i > 1
      return self + 's'
      return self

def from_seconds(seconds)
  t =
  mm, ss = t.divmod(60)
  hh, mm = mm.divmod(60)
  dd, hh = hh.divmod(24)
  output = []

  output.push("#{dd.to_i} day".plural) if dd > 0
  output.push("#{hh.to_i} hour".plural) if hh > 0
  output.push("#{mm.to_i} minute".plural) if mm > 0
  output.push("#{ss.to_i} second".plural) if ss > 0
  output.join(", ")
  # "%d days, %d hours, %d minutes, %d seconds" % [dd, hh, mm, ss]

def to_seconds(input)
  secs = {
    'w' => 604800,
    'd' => 86400,
    'h' => 3600,
    'm' => 60,
    's' => 1
  total = 0
  parts = input.gsub(/([wdhms])[a-z]+/,'\1').gsub(/[^wdhms\d]/,'').scan(/\d+\w/)
  parts.each do |p|
    num, qty = p.split(/(?=[wdhms])/)
    if secs.key? qty
      total += num.to_i * secs[qty]

if STDIN.stat.size > 0
  if RUBY_VERSION.to_f > 1.9
    Encoding.default_external = Encoding::UTF_8
    Encoding.default_internal = Encoding::UTF_8
    input ='utf-8')
    input =
  if ARGV.length > 0
    if ARGV[0].strip.match(/^(-h|help|--help)$/)
    input = ARGV.join('')

if input =~ /^\d+$/
  res = from_seconds(input)
  res = to_seconds(input)

Brett Terpstra

Brett is a writer and developer living in Minnesota, USA. You can follow him as ttscoff on Twitter, GitHub, and Mastodon. Keep up with this blog by subscribing in your favorite news reader.

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