TIL

Today I Learned

A collection of concise write-ups on small things I learn day to day across a variety of languages and technologies. These are things that don't really warrant a full blog post. These are mostly things I learn by pairing with smart people at Hashrocket.

328 TILs and counting...

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Categories

• Clojure
• Devops
• Git
• Go
• JavaScript
• Linux
• Mac
• PostgreSQL
• Rails
• Ruby
• tmux
• Unix
• Vim

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Clojure

• Aggregation Using merge-with
• Argument Requirements For A Function
• Evaluate One Liners With lein-exec
• Expanding Macros
• Get The Value Of An Environment Variable
• Load A File Into The REPL
• Mapping With An Index
• Open JavaDocs
• Pretty Print The Last Thing
• Quick Clojure Docs
• Reductions
• Set Max Heap Size
• Specify the Directory of a Shell Command
• Splitting On Whitespace
• Swap Two Items in a Vector
• Try A Clojure Project In The REPL
• Type of Anything
• When Overflow Is Desired

Devops

• Aliasing An Ansible Host
• Check The Status of All Services
• Check The Syntax Of nginx Files
• Determine The IP Address Of A Domain
• Path Of The Packets
• Push Non-master Branch To Heroku
• Reload The nginx Configuration
• Running Out Of inode Space
• Wipe A Heroku Postgres Database

Git

• Accessing a Lost Commit
• Amend Author Of Previous Commit
• Caching Credentials
• Checkout Old Version Of A File
• Checkout Previous Branch
• Clean Out All Local Branches
• Clean Up Old Remote Tracking References
• Delete All Untracked Files
• Determine The Hash Id For A Blob
• Dry Runs in Git
• Excluding Files Locally
• Find The Initial Commit
• Grab A Single File From A Stash
• Grep Over Commit Messages
• Ignore Changes To A Tracked File
• Intent To Add
• Interactively Unstage Changes
• Last Commit A File Appeared In
• List Filenames Without The Diffs
• List Most Git Commands
• List Untracked Files
• Move The Latest Commit To A New Branch
• Reference A Commit Via Commit Message Pattern Matching
• Renaming A Branch
• Resetting A Reset
• Single Key Presses in Interactive Mode
• Staging Changes Within Vim
• Staging Stashes Interactively
• Stashing Only Unstaged Changes
• Stashing Untracked Files
• Untrack A Directory Of Files Without Deleting
• Untrack A File Without Deleting It
• Verbose Commit Message
• What Is The Current Branch?
• Whitespace Warnings

Go

• Not So Random
• Replace The Current Process With An External Command
• Sleep For A Duration

JavaScript

• Character Codes from Keyboard Listeners
• Create An Array Containing 1 To N
• Enable ES7 Transforms With react-rails
• Random Cannot Be Seeded
• Splat Arguments To A Function
• Throttling A Function Call
• Transforming ES6 and JSX With Babel 6
• Truthiness of Integer Arrays

Linux

• Check Ubuntu Version
• Configure Your Server Timezone
• Upgrading Ubuntu

Mac

• Default Screenshot Location

PostgreSQL

• A Better Null Display Character
• Adding Composite Uniqueness Constraints
• Aggregate A Column Into An Array
• Auto Expanded Display
• Checking The Type Of A Value
• Compute Hashes With pgcrypto
• Configure The Timezone
• Constructing A Range Of Dates
• Count Records By Type
• Create A Composite Primary Key
• Create hstore From Two Arrays
• Creating Conditional Constraints
• Day Of Week By Name For A Date
• Day Of Week For A Date
• Default Schema
• Defining Arrays
• Edit Existing Functions
• Escaping A Quote In A String
• Export Query Results To A CSV
• Extracting Nested JSON Data
• Find The Data Directory
• Fizzbuzz With Common Table Expressions
• Generate A UUID
• Generate Series Of Numbers
• Get The Size Of A Database
• Get The Size Of A Table
• Getting A Slice Of An Array
• Insert Just The Defaults
• Integers In Postgres
• Intervals Of Time By Week
• Is It Null Or Not Null?
• Limit Execution Time Of Statements
• List All Columns Of A Specific Type
• List All Versions Of A Function
• List Database Users
• Max Identifier Length Is 63 Bytes
• pg Prefix Is Reserved For System Schemas
• Pretty Print Data Sizes
• Restart A Sequence
• Restarting Sequences When Truncating Tables
• Send A Command To psql
• Set Inclusion With hstore
• Set A Seed For The Random Number Generator
• Sleeping
• Special Math Operators
• String Contains Another String
• Temporarily Disable Triggers
• Temporary Tables
• Timestamp Functions
• Toggling The Pager In PSQL
• Truncate All Rows
• Truncate Tables With Dependents
• Turning Timing On
• Two Ways To Compute Factorial
• Types By Category
• Use A psqlrc File For Common Settings
• Use Argument Indexes
• Using Intervals To Offset Time
• Who Is The Current User
• Word Count for a Column

Rails

• All or Nothing Database Transactions
• Attribute Getter without the Recursion
• Attribute Was
• Autosave False On ActiveRecord Associations
• Capybara Page Status Code
• Code Statistics For An Application
• Conditional Class Selectors in Haml
• Creating Records of Has_One Associations
• Hash Slicing
• Ignore Poltergeist JavaScript Errors
• Migrating Up Down Up
• Params Includes Submission Button Info
• Pretend Generations
• Retrieve An Object If It Exists
• Select A Select By Selector
• Select Value For SQL Counts
• Set Schema Search Path
• Show Pending Migrations
• Show Rails Models With Pry
• Show Rails Routes With Pry

Ruby

• Are They All True?
• Assoc For Hashes
• Block Comments
• Colorful Output With MiniTest
• Comparing Class Hierarchy Relationships
• Comparing Arrays In RSpec
• Construct A Constant From A String
• Create an Array of Stringed Numbers
• Defaulting To Frozen String Literals
• Destructuring Arrays In Blocks
• Disassemble Some Codes
• Double Splat To Merge Hashes
• Editing Code In Pry
• Evaluating One-Off Commands
• FactoryGirl Sequences
• Finding The Source of Ruby Methods
• Identify Outdated Gems
• If You Detect None
• Invoking Rake Tasks Multiple Times
• Last Raised Exception In The Call Stack
• Limit Split
• Listing Local Variables
• Next And Previous Floats
• Override The Initial Sequence Value
• Parallel Bundle Install
• Pass A Block To Count
• Passing Arbitrary Methods As Blocks
• Passing Arguments To A Rake Task
• Percent Notation
• Question Mark Operator
• Rake Only Lists Tasks With Descriptions
• Replace The Current Process With An External Command
• Rendering ERB
• Returning With Sequel
• Safe Navigation Operator
• Set RVM Default Ruby
• Show Public Methods With Pry
• Squeeze Out The Extra Space
• Summing Collections
• Uncaught Exceptions In Pry
• undef_method And The Inheritance Hierarchy
• Who Are My Ancestors?
• Zero Padding

tmux

• Adjusting Window Pane Size
• Create A Named tmux Session
• Cycle Through Layouts
• Enabling Vi Mode
• Jumping Between Sessions
• List All Key Bindings
• List Sessions
• Open New Window With A Specific Directory
• Organizing Windows
• Paging Up And Down
• Pane Killer
• Reclaiming The Entire Window
• Rename The Current Session
• Swap Split Panes
• tmux in your tmux

Unix

• All The Environment Variables
• Cat A File With Line Numbers
• Change Default Shell For A User
• Check If A Port Is In Use
• Clear The Screen
• Copying File Contents To System Paste Buffer
• Create A File Descriptor with Process Substitution
• Do Not Overwrite Existing Files
• File Type Info With File
• Find Newer Files
• Global Substitution On The Previous Command
• Grep For Files Without A Match
• Grep For Multiple Patterns
• Hexdump A Compiled File
• Kill Everything Running On A Certain Port
• Killing A Frozen SSH Session
• List All The Say Voices
• List All Users
• Only Show The Matches
• Repeat Yourself
• Saying Yes
• Search History
• Search Man Page Descriptions
• Securely Remove Files
• SSH With Port Forwarding
• Switch Versions of a Brew Formula
• Watch The Difference
• Watch This Run Repeatedly
• Where Are The Binaries?

Vim

• Absolute And Relative Line Numbers
• Add A File Without Loading It
• Add Custom Dictionary Words
• Alternate Files With vim-rails
• Amend Commits With Fugitive
• Backspace Options
• Beginning And End Of Previous Change
• The Black Hole Register
• Breaking The Undo Sequence
• Buffer Time Travel
• Build And Install A Go Program
• Case-Aware Substitution With vim-abolish
• Case-Insensitive Substitution
• Center The Cursor
• Check Your Current Color Scheme
• Close the Current Buffer
• Coerce The Current Filetype
• Coercing Casing With vim-abolish
• Count the Number of Matches
• Create A New Directory In netrw
• Create A New File In A New Directory
• Creating Non-Existent Directories
• Delete Every Other Line
• Delete Lines That Match A Pattern
• Deleting Directories Of Files From netrw
• Difference Between :wq and :x
• Display Word Count Stats
• Edges Of The Selection
• End Of The Word
• Filter Lines Through An External Program
• Format Long Lines To Text Width
• Generate and Edit Rails Migration
• Grepping Through The Vim Help Files
• Head of File Name
• Help For Non-Normal Mode Features
• Highlighting Search Matches
• Horizontal to Vertical and Back Again
• Incremental Searching
• Increment All The Numbers
• Interactive Buffer List
• Joining Lines Together
• Jump To Matching Pair
• Jump To The Next Misspelling
• List All Buffers
• List Of Plugins
• Match The Beginning And End Of Words
• Marks Across Vim Sessions
• Moving To A Specific Line
• Navigating By Blank Lines
• NETRW Listing Styles
• Next Modified Buffer
• Open an Unnamed Buffer
• Opening a URL
• Opening Man Pages In Vim
• Paste A Register From Insert Mode
• Preventing Typos with Abbreviations
• Previous Buffer
• Previous Visual Selection
• Quick File Info
• Quick Man Pages
• Quick Quickfix List Navigation
• Re-indenting Your Code
• Rename Current File
• Repeat The Previous Change
• Repeating Characters
• Replace A Character
• Reverse A Group Of Lines
• Running Bundle With vim-bundler
• Scrolling Relative to the Window
• Searching For Hex Digits
• Set End Of Line Markers
• Set Your Color Scheme
• Split Different
• Splitting For New Files
• Swap Occurrences Of Two Words
• Swapping Split Windows
• Tabs To Spaces
• The Vim Info File
• Unloading A Buffer
• Verbose Commits With Fugitive
• View Commit History of a File
• Viewing Man Pages with man.vim
• Vim Without The Extras
• Whole Line Auto-Completion
• Wrap With Some Room

About

I shamelessly stole this idea from thoughtbot/til.

Other TIL Collections

• Today I Learned by Hashrocket
• jwworth/til
• thoughtbot/til

License

© 2015-2016 Josh Branchaud

This repository is licensed under the MIT license. See LICENSE for details.