The World Is a libferris Filesystem
Listing 1. A Long Listing of a Directory with Explicit Metadata
$ fls -l \ --show-ea=size-human-readable,width,height,name 4.5k 48 46 emacs.png 1.9k 48 48 gnome-warning.png 3.2k 48 48 gnome-xterm.png 2.5k 48 48 gtkvim.png
Listing 2. Asking libferris itself to determine which EAs are of interest for the current directory and producing an XML document as output.
$ fls -0 --xml <ferrisls> <ferrisls url="file:///tmp/lj" name="lj" > <context size-human-readable="4.5k" protection-ls="-rw-r-----" mtime-display="05 Dec 4 23:39" name="emacs.png" width="48" height="46" /> ... </ferrisls> </ferrisls>
As mentioned previously, if you are sorting a directory on an EA that does not provide a complete ordering, you can chain together sorting predicates. For example, in Listing 3, I have sorted the output based on the numeric EA height and then used a version string sort on the name EA. A version sort is similar to the ls(1) -v option, which in Listing 3 has placed foo20.png after foo3.png. Such sorting is very useful when sorting by file type or MIME major type followed by name.
Listing 3. Sorting Your Output
$ fls --show-ea=width,height,size,name \ --ferris-sort='(:#:height)(:V:name)' 48 48 1968 gnome-warning.png 48 48 3253 gnome-xterm.png 48 48 2550 gtkvim.png 48 46 4589 emacs.png 48 46 4589 foo3.png 48 46 4589 foo20.png
The two concepts of files forming a tree and files having key-value pairs attached to them are similar to the structure of XML. With libferris, you can poke inside XML documents as though they were just another filesystem. For example, see Listing 4.
Listing 4. Initial Exploration of XML as a Filesystem
$ cat example.xml <root> <file1 size="200" /> <file2 interesting="yes" /> <file3>filesystems rock </file3> </root> $ fls -0 ./example.xml/root file1 file2 file3 $ fls -d --show-ea=name,interesting \ ./example.xml/root/file2 file2 yes $ fcat example.xml/root/file3 filesystems rock
By interacting with your filesystem, you can cause updates on the underlying XML document as well. The ferris-redirect client exists to allow shell-like redirection into libferris files. The -T or --trunc option truncates an existing file before writing stdin into it. This is much like the >| shell option. As you can see from the interaction in Listing 5, we have changed the structure of the example.xml document significantly through filesystem interaction.
Listing 5. Changing an XML File through Its Filesystem
$ echo "VIRTUAL filesystems rock more" | \ ferris-redirect -T ./example.xml/root/file3 $ echo "a new way" | \ ferris-redirect ./example.xml/root/file4 $ ferrisrm ./example.xml/root/file2 $ ftouch ./example.xml/root/touched $ cat example.xml <?xml version="1.0" encoding="UTF-8" standalone="no" ?> <root> <file1 size="200"/> <file3>VIRTUAL filesystems rock more </file3> <file4>a new way </file4> <touched/> </root>
As many modern word-processing documents are XML inside a compressed container, libferris allows you to drill down into the office document as though it were a filesystem. In Listing 6, I am listing a simple OpenOffice.org Writer document as a filesystem.
Listing 6. OpenOffice.org Documents Are Filesystems Too
$ fls -lh show-ea=size,name,content \ ~/sample-oo-writer.odt/content.xml/ \ office:document-content/office:body/office:text 0 office:forms 18 text:p Paragraph number 1 0 text:p-1 116 text:p-2 This is the second paragraph ... 0 text:p-3 39 text:p-4 And in summary, this is really... 0 text:p=5 0 text:sequence-decls
A Xerces-C Document Object Model (DOM) can be obtained for any libferris filesystem, just as a Xerces-C DOM can be mounted as a libferris filesystem. Creation of a DOM for a filesystem is evaluated lazily, so you can get a DOM for file:// and only the parts of the DOM that are required are ever created.
The ability to convert any libferris filesystem into a DOM allows you to apply XSLT to your filesystems easily. The example C++ code in Listing 7 applies a stylesheet to a mounted OpenOffice.org document.
Practical Task Scheduling Deployment
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.
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- My +1 Sword of Productivity
- SUSE LLC's SUSE Manager
- Non-Linux FOSS: Caffeine!
- Managing Linux Using Puppet
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- Parsing an RSS News Feed with a Bash Script
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- Doing for User Space What We Did for Kernel Space
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