Emacs: Friend or Foe?
Now that you've had a crash course in Emacs LISP programming, let's move on to something more practical. Once you start customizing Emacs, you'll notice that your .emacs file gets to be quite large, and may take a while to load. You may be aware that Emacs allows you to byte-compile LISP source files for faster loading, so let's utilize that feature on our .emacs configuration file.
The first step is to create a directory for your personal Emacs LISP files to reside. At first this directory will contain only one file; namely, your initial configuration file; but later in life you may wish to write separate Elisp files. I use the directory emacs in my home directory for this purpose.
Next, copy your .emacs file to this directory, and rename it to something like startup.el.
Now, we replace the contents of .emacs with a short bit of code that byte-compiles emacs/startup.el and loads it. However, we only want to byte-compile startup.el if it is newer than its compiled counterpart, startup.elc. Here's the trick:
(defun byte-compile-if-newer-and-load (file) "Byte compile file.el if newer than file.elc" (if (file-newer-than-file-p (concat file ".el") (concat file ".elc")) (byte-compile-file (concat file ".el"))) (load file)) (byte-compile-if-newer-and-load "~/emacs/startup")
This is blatantly obvious, I'm sure, but by way of explanation: this bit of code defines a new function, byte-compile-if-newer-and-load (keeping in line with the Emacs' affinity for verbose function names), and executes it on ~/emacs/startup.el. We have now moved all of the Emacs configuration code to startup.el which is byte-compiled when necessary.
Emacs and the X Window System are two good things that are great together. In fact, my primary motivation for starting to use Emacs for the four thousandth time was to have an editor that incorporated many of the nice features of X, such as mouse-based region cut-and-paste, and so forth. Emacs 19 has support for many useful X-based features, some of which I'll introduce here.
The first thing that you might want to do when using Emacs under X is customize the colors. I'm no fan of black and white; and in fact, I prefer lighter fonts on a dark background. While you can customize Emacs' X-specific attributes using the X resource database (e.g., by editing ~/.Xdefaults), this isn't quite flexible enough. Instead, we can use Emacs internal functions such as set-foreground-color.
For example, in your startup.el file, you might include:
(set-foreground-color "white") (set-background-color "dimgray") (set-cursor-color "red")
which will set these colors appropriately.
Emacs also provides support for faces, used most commonly within font-lock-mode. In this mode, text in the current buffer is “fontified” so that, for example, C source comments appear in one font face, and C function names in another. Several of Emacs' major modes have support for font lock, including C mode, Info, Emacs-Lisp mode, and so on. Each mode has different rules for determining how text is fontified.
For simplicity, I employ faces of the same font, but which use different colors. For example, I set the “bold” face to light blue, and “bold-italic” to a sick shade of green. Each major mode has a different use for each face; for instance, within Info, the bold face is used to highlight node names, and within C mode, the bold-italic face is used for function names.
The Emacs functions set-face-foreground and set-face-background are used to set the colors corresponding to each face. For a list of available faces and their current display parameters, use the command M-x list-faces-display.
For example, I use the following commands in startup.el to configure faces:
(set-face-foreground 'bold "lightblue") (set-face-foreground 'bold-italic "olivedrab2") (set-face-foreground 'italic "lightsteelblue") (set-face-foreground 'modeline "white") (set-face-background 'modeline "black") (set-face-background 'highlight "blue") (set-face-underline-p 'bold nil) (set-face-underline-p 'underline nil)
The modeline face (which is referred to in the Emacs documentation as mode-line, for some reason) is used for the mode line and menu bar. Also, the function set-face-underline-p can be used to specify whether a particular face should be underlined. In this case I turn off underlining for the faces bold and underline. (A non-underlined underline face? Hey, this is Emacs. Anything is possible.)
In order to use all of these wonderful faces, you'll need to turn on font-lock-mode. You may also wish to enable transient-mark-mode, which causes the current region (text between point and mark) to be highlighted using the region face. The following commands will enable this.
(transient-mark-mode 1) (font-lock-mode 1)
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
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With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide