bradurani

class AddColumnUsersIsAdmin < ActiveRecord::Migration
  def change
    add_column :users, :is_admin, :boolean, null: false, default: false
  end
end

bradurani

git diff --name-only HEAD | grep -e \.rb$ | xargs -n 1 rubocop

bradurani

strace -e pattern command #match pattern, don't pipe to grep because strace prints to stderr

strace -e open man cat 2> strace.txt #filter open calls and save to strace.txt (via stderr)
strace -p pid #attach to running process
strace -f #also strace child processes
strace -c #show histogram table of num calls
strace -f -e trace=network curl google.com #networrk calls (parent and child processes)
strace -f -e trace=network -s 100 curl google.com #limit string args to 100 chars

bradurani

echo "enter command: "
read command

if [ "$command" = "kill humans" ]
then
  echo "I can't do that. These are great humans, I'm not gonna... these are fantastic humans"
elif [ "$command" = "do stuff" ]
then
  echo "I'm doing the best kind of stuff. Best stuff. It'll be great stuff"
elif [ "$command" = "save yourself!" ]

bradurani

class AddTableUsers < ActiveRecord::Migration
  phase :post_deploy
  disable_ddl_transaction!
  
  def change
    add_index :users, :is_admin, algorithm: :concurrently
  end

end

bradurani

grep -rnw . -e "pattern"   recursive,line #s, whole word - all lines with pattern in all files
grep -ril . -e "pattern"   recursive,ignore case,files names instead of lines - file name for files containing pattern
--include "*glob*"
--exclude "*glob*"
-h no file name
-o only matching part (no whitespace)

grep -Fq #fixed string, not regex, quiet, do not print anything
grep -Fq 'ERROR' log.txt #return true if any line in the file contains ERROR

bradurani

class CreateProducts < ActiveRecord::Migration[5.0]
  def change
    create_table :products do |t|
      t.string :name
      t.text :description
 
      t.timestamps
    end
  end
end

bradurani

var groceries = {
  "bread": 5.45
  "milk": 3.50
  "cheese": 6.23
  "avocados": 2.50
}

groceries["milk"]

bradurani

SELECT *
FROM foo

bradurani

class AddTableUsers < ActiveRecord::Migration

  def up
    add_column: :users, :admin, default: false
  end

  def down
    remove_column :users, :admin
  end