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Multitasking from the Linux Command Line + Process Prioritization

by Chris Jean

March 6th, 2009

Did you know that you aren’t limited to working on one thing at a time while on a Linux command line? You can actually “minimize” a program that you are in, get back to the command line, and then return to the program whenever you’d like.

When you run a program or script on the Linux command line (from now on referred to as the shell), you are creating a new job. For those that are used to GUI environments, each of these jobs is somewhat like a window on the desktop. Just as you can have multiple windows and switch between them, the shell is capable of managing multiple jobs and allows you to switch between them.

There is a lot to cover, so let’s start simple by describing what states a shell job can be in.

Categories Development, Linux, Tips 'n Tricks
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Cleaning Out Old Linux Kernels in Ubuntu

by Chris Jean

March 5th, 2009

Without the Linux kernel, Ubuntu (and all the other Linux distros) would not exist. Despite this, most Linux users don’t know what a kernel is nor understand that the reason that Ubuntu is a Linux distro is because the kernel is Linux. All most users of any Linux distro is likely to know is that they will eventually have a large number of kernels installed on their system cluttering up their boot menu.

Describing what a kernel is and what it does is beyond the scope of this post. I do highly recommend that you first read the Wikipedia article on computer kernels followed by the article on the Linux kernel itself. I’d really like to do a post explaining what a kernel is in simple terms so that readers can gain a better appreciation for it and what it does for your distro. Please leave a comment letting me know if you are interested in this writeup.

Anyways, back to the topic at hand. What do we do with all these kernels that litter our boot menu? How do we remove them not just from our boot menu but from our file system as well?

Categories Linux, Tips 'n Tricks
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4 Great Tools to Find Files Quickly in Ubuntu

by Chris Jean

March 4th, 2009

Many of you fellow Ubuntu users will be familiar with the “Search for Files” tool that allows you to look for files. As is true with most things in Linux, there are great desktop tools, but more power can be found in Terminal than any streamlined desktop tool can match.

Today, I’d like to introduce you to a few tools that can turn a chore of finding files into an easy process.

Categories Linux, Tips 'n Tricks
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Change Timezone in CentOS

by Chris Jean

March 3rd, 2009

You just got your new CentOS dedicated server, and you notice that times in your logs aren’t quite right. You check the time from the command line (run “date”), and find that the timezone is set to US Eastern or some other timezone. How do you get this changed?

Unfortunately, this is not an easy thing to figure out. Fortunately though, it’s not hard to do with the right directions.

Categories Linux, Tips 'n Tricks
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Using Vi/Vim as a Command Line Editor

by Chris Jean

February 27th, 2009

In many of my Tips ‘n Tricks or tutorial posts, I have commands that involve editing/creating files in Vi. For those that have never used Vi, it can be a daunting experience trying Vi for the first time.

There are many holy wars fought over the best editor to use from the *nix command line. I won’t claim that Vi is the best; rather, Vi is simply what I’m used to, it’s powerful, and it is always available on servers that I work on.

In order to best help those that don’t know how to use Vi but are interested in learning, this will serve as a very brief tutorial on how to get started.

Categories Development, Linux, Tips 'n Tricks
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Unzip Multiple Files from Linux Command Line

by Chris Jean

February 26th, 2009

Here’s a quick tip that will help you work with multiple zip files on the command line.

If you are in a folder and have three zip files in it (a.zip, b.zip, c.zip) that you want to unzip, “no problem,” you think, “I can take care of that with one command.” So, you quickly run the following:

unzip *.zip

However, rather than having the unzip program nicely unzip each file one after another, you receive the following:

Archive: a.zip
caution: filename not matched: b.zip
caution: filename not matched: c.zip

I’m sure that this is not what you were expecting. I know I certainly wasn’t expecting this when I first tried it. However, this problem can help us understand more of how the command line works.
Read More→

Categories Linux, Tips 'n Tricks
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Multiple Firefox Profiles in Ubuntu

by Chris Jean

February 23rd, 2009

When Windows was my main OS, I was a big fan of Portable Firefox. With Portable Firefox, I could do multiple installations of Firefox on my system that could be customized to run concurrently with other installs of Firefox. This allowed me to have tailored installations with different sets of plugins and features.

Why would I want to run more than one Firefox at a time? For me, the reason is that it eases development. Here are a few ways that I use multiple installs:

One install that was just the default install with no additional tweaks or add-ons and would have all cached data, authenticated sessions, and cookies cleared when closed. This was a great browser to use when I would test new code to make sure that it ran well on a stock Firefox. It also gave me a clean cookie and authentication slate so I could test sessions from scrath without clearing my main browser’s history, sessions, etc. If I wiped the slate clean on this browser, nothing was lost.
Since having a large variety of add-ons in Firefox has a tendency to slow things down, I had another browser that included all the major development tool add-ons. I would load this browser up when I needed to explore the DOM in detail, debug layout issues, debug Javascript, etc. This allowed me to streamline my main browser down to just the add-ons that I use frequently.
Since Portable Firefox isn’t installed and just resides in its own folder, I could load multiple versions of Firefox. This made it easy to test for compatibility problems between different versions.
I even played around with the idea of having a browser specifically for media. I would use it for music sources like Pandora and for video sources like Hulu or Red vs. Blue.

Last week, I looked around for a solution like Portable Firefox for Ubuntu. I quickly found a solution that wasn’t nearly as difficult as doing multiple installs: multiple profiles.

Categories Linux, Tips 'n Tricks
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Proper Adobe Flash Support on Ubuntu 64-bit

by Chris Jean

February 20th, 2009

In one of my earlier posts, I talked about setting up Ubuntu 64-bit on my Dell Studio 17 laptop. I provided some information on how I set up Flash on my system. This solution used the 32-bit release version of Adobe’s Flash plugin and nspluginwrapper to allow the 32-bit plugin to be used with the 64-bit version of Firefox. I had just a few problems with this solution:

Google Analytics would crash the entire browser if I tried to change the date range.
Hulu would always take at least a minute to load any video. Full length videos would sometimes take as long as five minutes to load.
Youtube would often times not work correctly.
Random parts of certain Flash applications would not work at all.
The new Hearts of Space Flash player didn’t work.
All too often, all Flash apps would fail. This resulted in every instance of Flash being replaced with a light-gray background.

Fortunately, I found a great solution to this problem: an actual 64-bit Adobe Flash Plugin.

Categories Development, Linux, Tips 'n Tricks
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SSH Tutorial for Ubuntu Linux

by Chris Jean

February 19th, 2009

I touched on this topic in my First Day with Ubuntu at the Office post under Accessing Remove File Systems; however, I thought that this deserved its own topic.

For those that don’t know SSH stands for Secure SHell. In very non-technical terms, SSH allows you to access a system running a SSH server over a network. This other system can be another computer in your home or a remote system on the other side of the planet. SSH will allow you to connect to that other system and communicate with it securely. All the data passed back and forth is encrypted, so you don’t have to worry about people sniffing your passwords or valuable data.

You may be asking what all of that means to you. What it means is that you can connect to and control a computer that is somewhere else with the computer that is sitting right in front of you. If you have a remote webserver running Linux, SSH will let you install software, edit files, change the server configuration, access the database, and more. Did you forget a file on your computer at home? No problem, just SSH into your home computer and send the file to your email account or copy it directly to your office computer.

Hopefully those quick examples of what you can do is enough to whet your appetite.

Categories Development, Linux, Tips 'n Tricks
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Easily View Images From Terminal in Ubuntu

by Chris Jean

February 17th, 2009

I have a quick Ubuntu tip for you today. You’re on the command line and have an image in the directory that you’re currently in. How can you easily view this image without loading Nautilus, browsing to the directory, and opening it from there? It turns out that the answer is very simple.

The default image viewer in Ubuntu is called Eye of Gnome. Using Eye of Gnome, you can quickly view the following images: ani, bmp, gif, ico, jpeg, pcx, png, pnm, ras, svg, tga, tiff, wbmp, xbm, and xpm.

To run Eye of Gnome from the command line, simply run “eog”. So, if you have a file called image.jpg in your current directory, you can simply run the following to view it:

eog image.jpg

Now you never again have to wonder what that image is as you’re browsing around in Terminal.

This tip will work for any distro running Gnome, such as Linux Mint.

Categories Linux, Tips 'n Tricks
Comments (13)

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