If LibreOffice starts too slowly or Acrobat Reader gets stuck in its start sequence yet again, then Gloobus Preview [1] can help if you just want to take a quick peek at a file. The program is a clone of Quick Look [2], the popular Mac OS X tool. It provides a preview of selected files via a simple keyboard shortcut.

Sushi [3] for Gnome 3.2 (gnome-sushi ) is a similar tool. It's based on Java and GtkClutter. Gloobus Preview is written in C++ and uses Gtk+.

Gloobus Preview delivers a high-quality preview for many file types without having to open one of the applications based on the MIME type. You can just select the file while pressing the Super key (the Windows key or Mac Command key on most keyboards)+Spacebar (in the case of Gloobus Preview) or the Spacebar (in the case of Sushi). Both programs display an image of the file's content.

Gloobus Preview even works well with Nautilus. If you're using one-click mode, simply click an empty space on the left, press and hold Super+Spacebar, and mark all the files with your left mouse button that you want to preview. It works with all the supported file formats (see Table 1). Similarly, Sushi shows a folder icon with the size and number of items (Figure 1).

Figure 1: Sushi shows basic data for the folder.

Some differences between Gloobus Preview and Sushi do exist. Moving to the bottom of the window in an image opened in Sushi displays crosshairs with which you can switch to full-screen mode. Gloobus Preview instead has a little icon, behind which is hidden a context menu for the window. Next to the opportunity to donate, Gloobus Preview provides a Blog entry that takes you quickly to the WordPress project page [4].

For audio and video files, both tools show a small control bar and present the files immediately, provided you have the required codecs installed (Figure 2). If the ID3 tags of an audio file reference an album cover as an image, for example, both programs show it. Pressing Esc or clicking the Close icon shuts down the preview.

Figure 2: If you've installed all the necessary codecs, Gloobus Preview and Sushi will play the video directly.

Installation

The gnome-sushi package is in the standard Ubuntu repository and is installable without any further configuration. To set up Preview on Ubuntu, add the necessary PPA from the package manager and install the gloobus-preview package (Listing 1). The company behind the preview tool provides two additional PPAs, with Elementary Desktop and Nautilus Elementary. If you've integrated either one of them, Preview is already installed.

$ sudo add-apt-repository ppa:gloobus-dev/gloobus-preview
$ sudo apt-get update
$ sudo apt-get install gloobus-preview

If you install the unoconv package, Gloobus Preview displays a preview of LibreOffice or OpenOffice documents. If you run the gloobus-preview-configuration program from the command line, you can add a few basic settings in a dialog (Figure 3).

Figure 3: Gloobus Preview provides a sparse set of configuration options.

Both Gloobus Preview and Sushi are designed as Gnome extensions. They work with Unity and Gnome Shell. Nautilus doesn't seem to be priority.

Conclusion

After working with Gloobus Preview or Sushi for a while, you'll soon feel comfortable with them, and you'll appreciate having them around. They can eliminate some of the irritation of dealing with an application's long startup time just to get a glimpse of the first page – especially if you're working with larger Office documents. For images, however, a simple viewer would work just as well.