zealinux

Bash getopts usage template

#!/bin/bash -e

function usage {

	cat <<EOM
Usage: $(basename "$0") [OPTION]...

zealinux

# lib/tasks/db.rake
namespace :db do

  desc "Dumps the database to db/APP_NAME.dump"
  task :dump => :environment do
    cmd = nil
    with_config do |app, host, db, user|
      cmd = "pg_dump --host #{host} --username #{user} --verbose --clean --no-owner --no-acl --format=c #{db} > #{Rails.root}/db/#{app}.dump"
    end
    puts cmd

zealinux

linux查看httpd进程数

ps -ef | grep httpd | wc -l

查看Apache的并发请求数及其TCP连接状态

netstat -n | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'

zealinux

#!/bin/bash
bundle check || bundle install --jobs 4 --retry 5

pids=( server.pid realtime_updater.pid )
for file in "${pids[@]}"
do
  path="tmp/pids/$file"
  if [ -f $path ]; then
    rm $path
  fi

zealinux

Client-side SSL

For excessively paranoid client authentication.

Using self-signed certificate.

Create a Certificate Authority root (which represents this server)

Organization & Common Name: Some human identifier for this server CA.

openssl genrsa -des3 -out ca.key 4096
openssl req -new -x509 -days 365 -key ca.key -out ca.crt

zealinux

# in controller

# for local files
send_file '/path/to/file', :type => 'image/jpeg', :disposition => 'attachment'

# for remote files
require 'open-uri'
url = 'http://someserver.com/path/../filename.jpg'
data = open(url).read
send_data data, :disposition => 'attachment', :filename=>"photo.jpg"

zealinux

require "open-uri"
require "net/http"

Error = Class.new(StandardError)

DOWNLOAD_ERRORS = [
  SocketError,
  OpenURI::HTTPError,
  RuntimeError,
  URI::InvalidURIError,

zealinux

1. Java uses static, declared typing:

   String hello = "Hello, World!";
   List<String> phrases = new ArrayList<String>;
   phrases.add(hello);
   phrases.add(null);
   phrases.add(123); // Compile error! Not a string.

zealinux

.git
.gitignore
doc
.yardoc
coverage
jsdoc
tmp
log
README.md
public/uploads/

zealinux

require 'faraday'

field_file_url = 'http://localhost/blah'
file_to_upload = 'test.txt'

connection = Faraday.new(field_file_url) do |builder|
	builder.request :multipart
	builder.request :url_encoded
	builder.adapter :net_http
end