Learn to Code, Learn to Think

I recently had a tweet that’s caused a bit of comment, and I wanted to expand on the point.

I’m a huge fan of the movement to teach people, especially kids, to code.

When you learn to code, you’re learning to think precisely and analytically about a quirky world. It doesn’t really matter which particular technology you learn, as long as you are learning to solve the underlying logical problems. If a student becomes a professional engineer, their programming ability will rise above the details of the language, anyway. And if they don’t, they will have learned to reason logically, a skill that’s invaluable no matter what they end up doing.

That you can apparently complete a three month Ruby bootcamp and get a job today is an artifact of a bizarre employment market, and likely unsustainable. But by dedicating three months to learning to think in a logical framework, you’ll also gain an ability that will open opportunities for you for the rest of your life.

bash: get http response codes for a list of URLs

I had a file with a list of URLs, and I wanted to grab the HTTP response codes for each of them. I’m sure this quick bash script isn’t the best way to do it, but it works, and I’ll probably want to do this again someday, so here it is!


while read line    
    echo $(curl --write-out %{http_code} --silent --output /dev/null $line)
done <$1 

How to get a random line from a file in bash.

I work with a lot of data, and while I’d like to pretend it’s all in upside-down quasi-indexed b-tree rocket ships or some other advanced database, the truth is that much of it is in text files. I often find myself wanting to see a random line from one of these files, just to get a sense of what the data looks like.

I thought there must be an easy bash way to do this, but I couldn’t find it (‘shuf’ isn’t installed on my server), so I turned to twitter, and now I’m pleased to present more methods for finding a random line than you ever expected!

sort -R | head -n 1

If you can use this, do so! If it isn’t available, consider one of the following commands:

@andrewgilmartin suggests using awk:

awk 'BEGIN { srand() } rand() >= 0.5 { print; exit }'

@devinteske offered one of the easiest to solutions to read:

tail -$((RANDOM/(32767/`wc -l</etc/group|tr -d ' '`))) /etc/group|head -1

@terrycojones piped up with this gem:

split -l 1 < file; cat `for i in x*; do echo $RANDOM $i; done | sort -n | cut -f2 -d' ' | head -n 1`; rm x*

@FirefighterBlu3 does sed++:

file=/etc/passwd; lc="$(($RANDOM % $(wc -l $file|awk '{print $1}')))"; sed -n "${lc}p" $file

@burleyarch collects the whole set:

f=YOUR_FILE; n=$(expr $RANDOM \* `cat $f | wc -l` \/ 32768 + 1); head -n $n $f | tail -1

All of the options using $RANDOM should be used with the understanding that the max possible value is 32767, so it will only be random on files that have fewer than 32,767 lines.

@xn with an excellent use of cut:

awk 'BEGIN { OFS="\t"; srand() } { print rand(), $0 }' | sort -n | cut -f2- | head -1

@paulrbrown with a badass example of od:

echo `cat /dev/urandom | od -N4 -An -i `' % '`wc -l < file` | bc | sed 's/-//g' | xargs -I % head -n % file | tail -n 1

And finally, from @alexlines, who actually developed his solution into a blog post:

dd if=file skip=$(expr $(date +%N) \% $(stat -c "%s" file)) ibs=1 count=200 2>/dev/null|sed -n '2{p;q;}'

And, of course, @ceonyc brought some comic relief:

@hmason Good bash one-liner? Take my code, please.

New York Times: Reinventing E-mail, One Message at a Time

Nick Bilton did a writeup of my homegrown e-mail scripts in the New York Times!

SMS to e-mail gateway: The SMS doorbell

Over at NYC Resistor, it was getting cold, and we needed a doorbell so visitors wouldn’t be stranded outside when the building was locked. A standard wireless model didn’t work reliably (the space is on the fifth floor, just out of range), so various members generally resorted to writing their phone numbers on a sign on the front door when they were expecting guests.

Since almost everyone has a mobile phone already, and SMS-based solution seemed appropriate. In order to implement this we need two things:

  1. An SMS shortcode
  2. A system to notify when the shortcode is triggered

It’s irritating and expensive to acquire your own shortcode, but there are several services that will allow you to use one in exchange for a small fee or advertisements in your messages. TextMarks is my favorite (I used TextMarks for my WhereAmI project). While TextMarks markets their service as a system for mobile mailing lists, they allow you to reserve a keyword and define a behavior (that can include pulling data from a URL!) to occur when that keyword is triggered.

Configuring TextMarks

textmarks_configurationSign up for TextMarks and choose a keyword. Configure the keyword to respond with the “First 120 characters on web page”, and point it at the future home of your script (you can always come back and modify this later).

Note the as the value of the msg parameter — this instructs TextMarks to send along any additional message contents as the value of that parameter. That means if someone were to text 41411 “doorbell hi this is hilary”, TextMarks would call the script with the param msg=hi this is hilary. This can be quite useful.

The Script

This script is written in Python, but you can use any scripting language you like. This particular script just sends an e-mail to an account when the ‘doorbell’ is rung, but you could have it do pretty much anything up to and including ringing a real bell (which may be coming soon!).

#!/usr/bin/env python
# encoding: utf-8
Created by Hilary Mason, feel free to use this code in your own projects.

import sys, os
import smtplib
import cgi
import cgitb; cgitb.enable()

class Doorbell(object):
	def __init__(self, msg):
		message = """
Subject: KNOCK KNOCK, someone is at the door!

		""" % msg
		server = smtplib.SMTP('smtp.gmail.com:587')
		server.login(self.GMAIL_USERNAME, self.GMAIL_PASSWORD)
		server.sendmail('YOURGMAILACCOUNT@gmail.com', ['YOURGMAILACCOUNT@gmail.com'], message)

		print "You knocked! You can also call us at 347-586-9270. <3, NYC Resistor"

if __name__ == '__main__':
	print "Content-Type: text/plainnn"

	form = cgi.FieldStorage()
	if 'msg' in form:
		w = Doorbell(form['msg'].value)
		w = Doorbell('There is an anonymous monkey at the door.')

And that's it! Provided you have your keyword configured to point at your script, and the script living at an accessible address, you'll get an e-mail whenever your SMS doorbell is rung and the person who sent the message will get back a cute response confirming their action.


This setup can be easily extended such that a message containing 'doorbell hilary' could e-mail only me, or be forwarded to my phone.

I'm curious to see if having a remotely accessible 'doorbell' will encourage pranksters -- we might need to add a password.

My code is on TV (and so am I)!

FoxNY did a piece featuring me and Diana as hackers who use our technical powers for good, not evil.

There are way too few female technologists on television, and I’m happy to do what I can to show that women kick ass with code! Look for my mischievous I’m-writing-infinite-nested-loops grin in the clip where I’m programming.

If this looks like fun to you, come join us at NYC Resistor (where the segment was filmed!) for Thursday night craft nights or for one of many awesome classes.

Following a group of Twitterers without exhausting SMS

I’m at SXSW, and I want an ability to see the latest Tweets from the group of Twitterers that I follow who are here in the area. I also have a limited number of text messages on my phone (1500, but still).

I coded up a quick app that allows you to great a group of twitterers and see their latest tweet on a mobile-friend page. Check it out.

Comments are welcome!