In today's post I'm going to show how to embed a text message into an image file. This type of messaging is known as steganography. Steganography is the practice of hiding secrets in such a way that only the intended message recipient would know to look for your hidden message.
In this basic form of secret messaging we'll be adding text onto the end of a file. I'm going to use the following image of Tux for my example. Read more
Today I'm going to show you how to use the head and tail commands to view portions of text files. There are, of course, other commands that can be used to view text files. The cat command can be useful for viewing small text files while more and less can be good for larger files. But what if you're only interested in just the beginning or the end of a file? That's where head and tail come in. Read more
Filed under: command line, HowTo, image editing, linux, Ubuntu
As smart phones are becoming more pervasive, 2D bar codes are starting to appear all over the place. The QR Code format is one of the most commonly used styles of these matrix bar codes. These QR Codes often contain a URL to send a smart phone user to a particular web site, but all kinds of textual information can be embedded in these codes.
A while back I wrote a post on how to remove old kernels from your Ubuntu system. While that process works just fine, it is a four step process. One person who read that post left a comment with a nice command line one-liner that removes all but the currently running kernel. And while that one-liner works quite well, I must admit that I don't understand all the regular expressions used in it, so I decided to try and come up with my own one-liner to remove the old kernels from my system. Read more
In the previous installments of Command Line Basics: Ripping Audio CD's, I've gone through ripping CD's and saving the files as WAV files, transcoding those files to Ogg Vorbis audio, and finally, querying an online CD database tagging those Ogg files. I the last installment, I promised to show a more automated way to do this. Yes, you could write your own Bash script to automate some of the steps, but as is often the case with Open Source Software, someone else has already done the work for you. Read more