Run same command on different input/inputs

If you have to run the same command repetitively over different input/inputs.

Example input:

c595270372e3
c04094382ae1
498a6505a1f7
4ac0e1872789
170a7f2ec51a
930743cb4e19


Command:

pbpaste | xargs -I id docker image rm id


Note: pbpaste is clipboard paste command for Mac, would be different for operating systems.

1
Babar

Check for IKEA item availability

A bit of a hack, but we want to be notified if an item becomes available at IKEA.

This is just a shell script that should work on any *NIX that has curl installed.

This is how their API response looks like (replace th with your country code): https://www.ikea.com/th/en/iows/catalog/availability/S99067497

There are only two stores in Thailand, both of which are close enough to the Oozou office, we only care that it's available in one of those stores.

#!/usr/bin/env bash

url="https://www.ikea.com/th/en/iows/catalog/availability/$1"

# This is the string that we want to see changed
string="0"

while true; do
  # Get the API response and return as string
  text=$(curl -s "$url")

  # Get a count of how many times the substring matches
  count=`grep -o "$string" <<< "$text" | wc -l`

  # If less than 2, then it's available!
  if (( $count < 2 )); then
    echo "AVAILABLE, yay.";
    # Notify us via Slack
    curl -X POST --data-urlencode "payload={\"channel\": \"…\", \"username\": \"ikea\", \"text\": \"Item $1 is now available at IKEA.\", \"icon_emoji\": \":shooping_bags:\"}" https://hooks.slack.com/services/…
    break
  else
    # If not available, sleep for 30s
    echo "$1 not in stock"
    sleep 30
  fi
done



Pass in your item ID to start:

$ ./check.sh S99067497


5
Const

Create Element with attributes in one line

We normally use this kind of code to create a HTML element with JS:

const a = document.createElement('a')
a.setAttribute('class', 'foo bar')
a.setAttribute('id', 'id')
a.setAttribute('innerHTML', 'Hello World!')
a.setAttribute('href', 'https://www.google.com/')


Or some similar ways. But setting each attribute one by one is tedious!

We can do this in a single line if we want:

Object.assign(document.createElement('a'), {
  id: 'id',
  class: 'whatever class',
  href: 'https://www.google.com/',
  innerHTML: 'This is a link'
});


One more way to mess up with your JS codebase!

4
Babar

Change Ruby version for single command with rbenv

You can switch Ruby version temporarily with rbenv local

But it'd need to be switched back after you're done. Specially for a single command it's kind of pain. In those cases, you can use RBENV_VERSION env variable.

RBENV_VERSION=2.6.3 ruby -v


This might be useful in a shell script or so.

1
Babar

Go through a file Git history (GUI)

$ gitk --follow file


Ali

Reset Postgres table sequence after DELETE

When deleting recent records from a table, you can reset it's sequence counter if auto-increment field continuity is important to you. Consider actions on the following table, users
 
select max(id) from users;

+-----+ | max | +-----+ | 896 | +-----+ 1 rows in set (0.03 sec)

Then, some delete action against most recent rows: 
delete from users where created_at > timestamp 'yesterday';
96 rows in set (0.15 sec) 

The next auto-increment value for id would be 897 on the next insert. Use the following command to reduce the sequence value for the users table by 96.
select setval('users_id_seq',(select max(id) from users));

+--------+
| setval |
+--------+
| 800    |
+--------+
1 rows in set (0.04 sec)
1
Jeff

Kill unresponsive SSH session

Occasionally an SSH session may become unresponsive. If I put my laptop to sleep this happens fairly often. Rather than killing the tab you can use SSH Escape Characters to kill the session

$ ~.


To view all escape characters check man ssh and search for ESCAPE CHARACTERS $ /ESCAPE CHARACTERS

Joe

PostgreSQL UPDATE Join

This query shows how to use the PostgreSQL UPDATE join syntax to update data in a table based on values in another table. for example;

updating subscription_missions.giftbox_type with rewards.gift_box_type through mission_rewards table (tested on 300k records, crazy level fast)

  UPDATE
        subscription_missions sm
  SET
        giftbox_type = r.gift_box_type
  FROM
        mission_rewards mr,
        rewards r
  WHERE
        sm.giftbox_type IS NULL
        AND sm.id = mr.subscription_mission_id
        AND mr.reward_id = r.id;



Ali

Kill rails that got stuck

I'd like to kill rails running w/specific port. (My laptop running several rails servers. )

kill -9 $(lsof -i :3000|grep ruby|head -1|awk '{print $2}')

Alyson

Automagical Intermediate-level Hashtables in Ruby

All intermediate-level hashtables will be created automagically

def autovivifying_hash
   Hash.new {|ht,k| ht[k] = autovivifying_hash}
end


Usage

response_builder = autovivifying_hash
response_builder['payment']['status'] = 'OK'
response_builder # => {"payment"=>{"status"=>"OK"}


Ali