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Dear PostgreSQL: Where are my logs?

By Josh Tolley
November 12, 2014

Photo by Jitze Couperus

When debugging a problem, it’s always frustrating to get sidetracked hunting down the relevant logs. PostgreSQL users can select any of several different ways to handle database logs, or even choose a combination. But especially for new users, or those getting used to an unfamiliar system, just finding the logs can be difficult. To ease that pain, here’s a key to help dig up the correct logs.

Where are log entries sent?

First, connect to PostgreSQL with psql, pgadmin, or some other client that lets you run SQL queries, and run this:

foo=# show log_destination ;
 log_destination 
-----------------
 stderr
(1 row)

The log_destination setting tells PostgreSQL where log entries should go. In most cases it will be one of four values, though it can also be a comma-separated list of any of those four values. We’ll discuss each in turn.

Syslog

Syslog is a complex beast, and if your logs are going here, you’ll want more than this blog post to help you. Different systems have different syslog daemons, those daemons have different capabilities and require different configurations, and we simply can’t cover them all here. Your syslog may be configured to send …

Finding specific Git commit at a point in time

By Greg Sabino Mullane
November 10, 2014

Some car by William Warby

When using Git, being able to track down a particular version of a file is an important debugging skill. The common use case for this is when someone is reporting a bug in your project, but they do not know the exact version they are using. While normal software versioning resolves this, bug reports often come in from people using the HEAD of a project, and thus the software version number does not help. Finding the exact set of files the user has is key to being able to duplicate the bug, understand it, and then fix it.

How you get to the correct set of files (which means finding the proper Git commit) depends on what information you can tease out of the user. There are three classes of clues I have come across, each of which is solved a different way. You may be given clues about:

1. Date: The date they downloaded the files (e.g. last time they ran a git pull)
2. File: A specific file’s size, checksum, or even contents.
3. Error: An error message that helps guide to the right version (especially by giving a line number)

Finding a Git commit by date

This is the easiest one to solve. If all you need is to see how the repository looked around a certain point in …

Where is pg_ctl on CentOS 6 for Postgres 9.3?

By Spencer Christensen
November 7, 2014

When installing PostgreSQL 9.3 onto a CentOS 6 system, you may notice that some postgres commands appear to be missing (like pg_ctl, initdb, and pg_config). However, they actually are on your system but just not in your path. You should be able to find them in /usr/pgsql-9.3/bin/. This can be frustrating if you don’t know that they are there.

To solve the problem, you could just use full paths to these commands, like /usr/pgsql-9.3/bin/initdb, but that may get ugly quick depending on how you are calling these commands. Instead, we can add them to the path.

You could just copy them to /usr/bin/ or create symlinks for them, but both of these methods are hack-ish and could have unintended consequences. Another option is to add /usr/pgsql-9.3/bin/ to your path manually, or to the path for all users by adding it to /etc/bashrc. But again, that seems hack-ish and when you upgrade postgres to 9.4 down the road things will break again.

So instead, let’s look at how Postgres’ other commands get installed when you install the rpm. When you run “yum install postgresql93” the rpm contains not only all the files for that package but it also includes some scripts to run (in this case one at …

Simplifying mobile development with Ionic Framework

By Kamil Ciemniewski
November 6, 2014

My high school math teacher used to say that mathematicians are the laziest people on Earth. Why? Because they always look for clever ways to simplify their work.

If you stop and think about it, all that technology is, is just simplification. It’s taking the infinitely complex world and turning it into something sterile and simple. It’s all about producing simple models with a limited number of elements and processes.

Today I’d like to walk you through creation of a mobile app that could be used on iOS, Android or Windows Phone. We’ll use a very cool set of technologies that allow us to switch from using multiple languages and frameworks (Objective-C for iOS, Java for Android and C# for Windows Phone) to just using HTML, CSS and JavaScript.

Let’s start turning complex into simple!

PhoneGap and Ionic Framework

Creating the project

In order to be able to start playing along, you need to get yourself a set of toys. Assuming that you’ve got NodeJS and Npm installed already, all you have to do is:

$ npm install -g cordova ionic

Now you should be able to create the project’s scaffold. We’ll be creating a simple app that will list all the latest cartoons from the xkcd blog. Let’s call it …

CSS table-cells ::before and ::after

By Kent Krenrich
November 5, 2014

When laying out HTML forms, instead of using a table (re: tables-are-only-for-tabular-data et al), I’ve had good results making use of the table family of values for the CSS display property. I find it a reliable way to ensure items line up in a wide range of situations, a change in the size of labels or a resize of the browser’s window for example.

Something simple like the following has worked well for me on several occasions:

.table {
  display: table;
}
.table>* {
  display: table-row;
}
.table>*>* {
  display: table-cell;
}

Occasionally though, I’ve wanted to leave a column empty for one reason or another. To accomplish this I found myself including empty HTML tags like:

<form class="table">
  <div>
    <div>A Cell</div>
    <div>A Cell</div>
  </div>
  <div>
    <div></div>
    <div>A Cell</div>
  </div>
</form>

The empty elements function well enough but they feel a little out of place. Recently I came up with a solution I like better. By using the CSS ::after and ::before selectors, you can insert an arbitrary element that can take the place of a missing cell. The following …

OpenSSL CSR with Alternative Names one-line

By Emanuele “Lele” Calò
October 30, 2014

2017-02-16—​Edit—​I changed this post to use a different method than what I used in the original version cause X509v3 extensions were not created or seen correctly by many certificate providers.

I find it hard to remember a period in my whole life in which I issued, reissued, renewed and revoked so many certificates.

And while that’s usually fun and interesting, there’s one thing I often needed and never figured out, till a few days ago, which is how to generate CSRs (Certificate Signing Requests) with AlternativeNames (eg: including www and non-www domain in the same cert) with a one-liner command.

This need is due to the fact that some certificate providers (like GeoTrust) don’t cover the parent domain when requesting a new certificate (eg: CSR for www.endpoint.com won’t cover endpoint.com), unless you specifically request so.

Luckily that’s not the case with other Certificate products (like RapidSSL) which already offer this feature built-in.

This scenario is starting to be problematic more often since we’re seeing a growing number of customers supporting sites with HTTPs connections covering both www and “non-www” subdomains for their site.

Luckily the solution is pretty simple …

Prevent MediaWiki showing PHP version with new extension: ControlSpecialVersion

By Greg Sabino Mullane
October 29, 2014

Sok Kwu Wan

I recently created a new MediaWiki extension named ControlSpecialVersion whose purpose is to allow some control over what is shown on MediaWiki’s “special” page Special:Version. The latest version of this extension can be downloaded from Mediawiki.org. The primary purpose of the module is to prevent showing the PHP and database versions to the public.

As with most MediaWiki extensions, installation is easy: download the tarball, unzip it into your extensions directory, and add this line to your LocalSettings.php file:

require_once( "$IP/extensions/ControlSpecialVersion/ControlSpecialVersion.php" );

By default, the extension removes the PHP version information from the page. It also changes the PostgreSQL reported version from its revision to simply the major version, and changes the name from the terrible-but-official “PostgreSQL” to the widely-accepted “Postgres”. Here is what the Software section of bucardo.org looks like before and after the extension is used:

Note that we are also eliding the git revision information (sha and date). You can also do things such as hide the revision information from the extension list, remove the versions entirely, or even …

Another Round of Tidbits: Browser Tools, Performance, UI

By Steph Skardal
October 20, 2014

It’s been a while since I shared a blog article where I share End Point tidbits, or bits of information passed around the End Point team that don’t necessarily merit a single blog post, but are worth mentioning and archiving. Here are some notes shared since that last post that I’ve been collecting:

• Skeuocard and creditcard.js are intuitive user interface (JS, CSS) plugins for credit card form inputs (card number, security code, billing name).

Skeuocard Screenshot

• StackExchange UX is a Stack Overflow resource for user interface Q&A.
• wpgrep is an available tool for grepping through WordPress databases.
• Here is a nifty little tool that analyzes GitHub commits to report on language convention, e.g. space vs. tab indentation & spacing in argument definitions.

Example comparison of single vs. double quote convention in JavaScript.

• Ag (The Silver Searcher) is a document searching tool similar to ack, with improved speed. There’s also a Ag plugin for vim.
• GitHub released Atom earlier this year. Atom is a desktop application text editor; features include Node.js support, modular design, and a full feature list to compete with existing text editors.
• SpeedCurve is a web …