Get the path of script.
p __dir__
Get current directory.
p Dir.pwd
Escape html.
require "cgi/util"
CGI.escape_html("< > & \"") # => "< > & ""
Write and read from file.
File.write('foo.txt','hello')
# => 5
File.read('foo.txt')
# => "hello"
Read file(for larger file).
File.foreach('foo.txt') do |line|
puts line
end
Read as CSV.
require 'csv'
CSV.foreach("foo.csv",encoding:"cp932",col_sep:"\t") do |row|
puts row
end
Get disk space via df command(without installing any gems).
def df(pat) # i.e. /dev/vda3
res = `df -h | grep #{pat}`.strip
res.split(/ +/)[1,4] # ["14G", "4.6G", "8.8G", "35%"]
end
Read and write JSON.
require 'json'
data = JSON.parse(File.read("foo.json"))
File.write("bar.json",JSON.pretty_generate(data))
To activate load data local .. on MySQL8.0, need to set local_infile: true.
client = Mysql2::Client.new(host: "localhost", username: "user", local_infile: true)
client.query("use db")
results = client.query("select * from t")
results.each do |row|
puts row
end
client.close
Get current time.
Time.now.strftime("%F %T")
# => "2022-01-29 21:14:09"
require 'optparse'
e = false # flag for execution
options = {}
OptionParser.new do |opts|
opts.banner = "Usage: foo.rb [-a foo] [-b bar] [-e]"
opts.on("-a", "--apple foo", "Foo") { |v| options[:a] = v }
opts.on("-b", "--banana bar", "Bar") { |v| options[:b] = v }
opts.on("-e", "--execute", "Execute all commands.") { |v| e = true }
end.parse!
require './geo_3x3'
lat, lng = 31.908714674017606, 131.42030837301505
level = 18
puts "#{lat},#{lng}"
geo = Geo3x3.encode(lat,lng,level)
puts geo
p Geo3x3.decode(geo)