Free file viewer software for linux

Preview is a simple image viewer for GNUstep. It is designed to be easy to use and support GNUstep features such as image design, pasteboard/services, printing, and layout.

Opcion Font Viewer is a free font viewer written in Java that allows you to view both installed and uninstalled TrueType fonts on Windows, Linux, Unix or Mac.
The main focus of Opcion is to allow you to view your uninstalled fonts so that you install only the fonts you want and keep your system memory free of fonts you dont want.
As you may have experienced, installing the brand new 1000 fonts font pack you just bought on your Windows, Linux, Unix or Mac computer can lead to slow-downs when starting the computer and when loading other programs.
The slow down occurs because the Operating System and certain programs (e.g. word-processors, email clients, graphics editors) need to load all system fonts so that they can be made available to you at any time. This is where Opcion comes in.
Opcion was written to handle the viewing of large font collections, therefore only fonts that you are currently viewing are stored in memory. Although the amount of physical memory you have will effect how many fonts you can view at a time, it will no longer be a limitation to you making use of your entire font library.
Another problem with most Operating Systems default font viewers is that while they are capable of viewing fonts, the default Windows/Linux/Unix font viewers only allows you to view fonts that are already installed and one at a time. Opcion allows you to view TrueType fonts located anywhere and allows you to view system fonts as well.
To help you pick the best font for the job, whether it be for your assignment, project logo or webpage, Opcion provides a list view of either system or other/uninstalled fonts so you may see how a font looks compared to other fonts in your collection.
When you see a font that you feel suits your current job you can simply click on it in the list view and it will be added to a favourites list that can then be saved for future reference or used to install only the fonts you want.
For viewing fonts, seeing how they would appear applied to your name/logo/tagline, and keeping track of which fonts best suit the job is the purpose of Opcion Font Viewer. Opcion allows you to view both installed and uninstalled fonts in different views depending on your needs. Written in Java, Opcion will work on all platforms that the Java Runtime Environment supports (which includes Windows, Mac, Solaris & Linux).
Opcion Font Viewer provdies a default view that allows you to view one font at a time, and a list view which allows you to view multiple fonts at a time. By clicking on fonts you like in the list view you are adding fonts to a faviourties list that Opcion keeps for you. The faviourites list can then be saved for future reference or used in finding out the file names of fonts you wish to install.
Main features:
- Viewing of installed/uninstalled fonts.
- List view of installed/uninstalled fonts.
- Adding/removing of favourite fonts.
- Saving of favourite fonts.
- Customizable sample/display text.
- Customizable font size.
- Customizable font properties (bold, italic, etc.) in sample text area.
- Changeable fonts displayed per page in List View.
Execute Opcion Font Viewer
To execute Opcion Font Viewer in Windows, download the EXE version. For Linux users use the command "java -jar Opcion_v1.1.1.jar" in console/terminal/shortcut.
Exception in thread "main" java.lang.UnsatisfiedLinkError: /usr/java/j2re1.4.1_02/lib/i386/libfontmanager.so: libstdc++-libc6.1-1.so.2: cannot open shared object file: No such file or directory
This error occurs due to backwards compatibility issues with the Java Runtime and libstdc. To fix this problem for RedHat 9.0 install the RPM file compat-libstdc++-7.3.2.96.118.i386.rpm, which can be found on disc 1 of the downloadable distro. For other Linux distributions check rpmfind.net for libstdc++-libc6.1-1.so.2 to see what package you need to install.
An unexpected exception has been detected in native code outside the VM.
Unexpected Signal : 11 occurred at PC=0x4CAEE920 Function=(null)+0x4CAEE920 Library=/usr/local/lib/SunJava2-1.4.2/lib/i386/libfontmanager.so
This error appears to be a problem with Sun Microsystems Java implementation for Linux, the real cause for this crash is still being investigated. There are no solutions to this problem yet.
Opcion crashes during execution when using Blackdown Java Virtual Machine.
Opcion Font Viewer was programmed for Sun Microsystems JVM, and it uses Suns Java API extensively. Thus, it is highly recommended that you use the latest Java Runtime Environment instead of other JVMs.
Enhancements:
- Added sorting to other fonts list.

JProfiler is an award-winning all-in-one Java profiler. JProfilers intuitive GUI helps you find performance bottlenecks, pin down memory leaks and resolve threading issues.
Even though JProfiler has a powerful feature set, its a Java profiler that is extremely easy to use! JProfilers user interface provides a unified view on the profiled application and puts all the information you need right at your fingertips with its intuitive hierarchy of views.
Configure your application for profiling
When starting up JProfiler, the start center is brought up. Here you can manage and start your profiling sessions. To configure your application for profiling, change to the "New session" tab and click on the New session button. Enter the required information into the session config dialog as described below and select Ok to start profiling. Thats all it takes. Note the Help button which appears on all of JProfilers dialogs displays a context sensitive explanation of all features.
While the configuration dialog displays numerous options that you will not want to miss after becoming familiar with JProfiler, entering the basic pieces of information is really very simple:
1. Enter a name for your session.
2. Enter the name of your main class.
3. Enter your class path.
4. Press Ok.
Before profiling is actually started, the profiling settings dialog is displayed where you can select the focus for your profiling run. Although profiling produces an overhead when running your application, you can minimize it by choosing a setting for which JProfiler only records information that is interesting for you.
If you want to fine-tune your profiling settings, the [Edit] button brings up a dialog with all available configuration options for profiling.
Observe classes and allocations
To find out what is going on the heap in terms of objects and classes, turn to the classes monitor. It gives you continuous updates and lets you set marks to observe changes over time. To see references, allocations and object data for your selection, you can take a snapshot by clicking on the camera in JProfilers toolbar.
If you want to know where your objects are allocated, you can go to the allocation monitor. Here, you can inspect the call tree and find out what method calls have caused the allocation of a selected class or package. Just like in the allocation monitor, you can display this data for live and garbage collected objects.
An cumulated overview on which methods are responsible for allocations is given by the allocation hot spots view. Each hot spot can be expanded and the backtraces that lead to the invocation of the hot spot are displayed. You can also mark the current values and view the differences in allocations over time.
Find memory leaks
JProfilers heap walker works like a browser: it displays a current set of objects that can be changed by adding selection steps with the [Use selected] button. You can inspect the current object set in the four views of the heap walker.
In the classes view, you can select one or several classes and add a selection step. The new object set will contain only the selected instances. This is often the first thing you want to do after taking a snapshot. You can perform this step automatically by invoking the heap walker from the classes monitor.
The allocations view of the heap walker shows the allocation tree and the allocation hot spot list of the current object set. You can add a selection step for one or multiple allocation spots or hot spots. The new object set will then be restricted to the selected instances only.
When youre looking for the cause of a memory leak, the reference view is the most important view in JProfiler. Here, you can find out why an object has not been garbage collected. Use the "Show path to GC root" function to show where the JVM hangs on to the selected instance.
Not only is the heap walker your first stop for finding memory leaks, it also makes for an excellent debugging facility. In the data view, you can inspect instances, arrays and classes in the current object set and navigate along references. There are many situations where the usual debugging approach will fail and JProfiler will help you find out.
Zoom in on performance bottlenecks
Controlling your applications performance may be driven by quality of service constraints or by general quality assurance, JProfilers CPU views lend themselves naturally to both approaches.
To record CPU data, you switch to the CPU section and click on the recording button in JProfilers tool bar. The first view in the CPU section shows the invocation tree, cumulated for all threads. To find performance related problem spots, just follow the big percentages when opening the tree nodes. Also, the absolute times and the number of invocations that are displayed for each node can help you in getting a feeling for the situation. Once you become familiar with JProfiler, you may want to customize this view to best fit your personal preferences.
The invocation tree is a top-down view on the method calls of your application. This viewpoint is most useful when you experience an actual performance bottleneck in your application. If you want to improve overall performance, a bottom-up view may be more applicable.
This kind of view - called hot spots view - shows the methods where most of the time is spent. By opening these nodes you get backtraces which show the various invocation paths together with the percentages of their contributions. Note that by default, method calls within Java core classes are not shown separately - each of your library calls is treated as opaque. You can change this behavior by deactivating the corresponding filter sets.
The method graph combines both viewpoints. Incoming and outgoing method calls are presented in the same way. For a number of situations, the method graph can give you more insight than the invocation tree and the hot spots view. The best strategy is to use the invocation and hot spots views first and switch to the method graph for detailed analysis.
Solve thread-related problems
Threads can be exceptionally difficult to debug, especially if you dont have sufficient information on the actual sequence and status of the threads in your application. JProfilers thread views provide you with exactly this knowledge.
The thread history view shows a continuous update of the lifelines of all threads on the horizontal axis. The names of the threads are displayed on the vertical axis in the order of their creation. Each color signifies a different thread status. Orange means that the thread was sleeping, green stands for a runnable thread while red is displayed if the thread was waiting for a monitor. You can zoom in and out to your desired detail level or have the time axis fit your windows size automatically.
If youre more interested in whats happening right now, the thread monitor view is the right place to look at. Here, you can sort threads, filter with respect to thread status and view additional information on each thread.
Should you ever have a deadlock in your application, the deadlock detection graph will help you analyze the involved threads and the locking situation. Simple deadlocks like the one shown could be worked out by hand from the other views, but for complicated deadlock involving a greater number of threads this view is indispensable.
Reducing general monitor contention and debugging locking sequences requires a detailed view of the current monitor usage and a history of all monitor-related events. JProfiler has both. Below you see the monitor usage history which shows a blocking event together with the stack trace of the waiting thread.
Keep an eye on your JVM
Monitoring cumulative parameters of the virtual machine can be a highly fruitful activity, even if everything seems to be all right. Measuring and observing parameters like heap size, object count, loaded classes and thread numbers can point to dangerous trends and problematic behavior to look out for. In its VM telemetry view section, JProfiler features various telemetry controls which provide you with the information you need to stay one step ahead.
The number of objects on the heap, split in arrays and non-arrays. This is your first stop if you are suspecting a memory leak. All objects with live references are included, as well as those which are unreferenced but the garbage collector hasnt had a chance to collect yet.
The garbage collector activity which displays freed and moved objects. If your application is thrashing the heap excessively, this will show up here. Moving large numbers of objects places a high burden on the virtual machine and can lead to temporary freezes. Mostly this occurs when the virtual machine is enlarging the heap.
The number of threads in the virtual machine, split in active and inactive threads. This is useful if you create a large number of threads and need information on changes in their total number and how many of them actually run.
Enhancements:
- New futures:
- rewritten eclipse 3.x integration
- rewritten IDEA 4.x integration
- IDE integration for JDeveloper
- IDE integration for Netbeans 4.0
- considerably reduced memory consumption
- improved long-term stability for profiling
- heap walker: in the cumulated incoming reference view, reference holders as well as referenced objects can be displayed and selected
- option to keep the profiled JVM alive
- support for Java Web Start 1.5
- CSV export for graphs
- enhancements in XML export for trees
- integration wizard for profiling servers in IBM WSAD
- integration wizards for Pramati 3.5 and Pramati 4.x application server
- integration wizard for Websphere 4.0 Advanced Edition
- integration wizard for Sun Java System Web Server
- integration wizard for Sun Java System Application Server
- integration wizard for Oracle 10g Application server
- integration wizard for Apple WebObjects Developer 5.x
- snapshot files (*.jps) can be opened from the command line and from the Windows explorer
- JBuilder IDE integration now supports JBuilder 2005
- much better appearance of the JProfiler GUI with Windows native look and feel
- JProfiler GUI now also runs under Java 1.5
- Bug fixes:
- monitor statistics were broken
- invalid class files caused a shutdown of the profiled application
- many bug fixes in the GUI

pcpViewer is a 3D viewer of data gathered through the excellent "Performance Co-Pilot" library.

You can see usage of CPU time, net devices, memory, hard drives, and virtually any data exported by the pcp library and daemon.

I first started this "pet project" as a 3D xosview replacement (thanks for inspiration), so one of the goal is to get the same level of responsiveness as xosview.

Thuban is an interactive geographic data viewer (GIS viewer) which features methods to visualize, explore, and analyze geographic information.
Main features:
- Vector Data Support: Shapefile, PostGIS Layer
- Raster Data Support: GeoTIFF Layer
- Comfortable Map Navigation
- Object Identification and Annotation
- Legend Editor and Classification
- Table Queries and Joins
- Projection Support
- Printing and Vector Export
- API for Add-Ons (Extensions)
- Multi-Language Support: English, French, German, Hungarian, Italian, Russian and Spanish
- User Manual (English)

Process Viewer is a small utility similar to top which displays all the processes on a linux system. Its written using the FOX Toolkit.

Process Viewer is licensed under the GNU General Public License

DGuitar is a Guitar Pro (*.GP4, *.GP3, GTP) viewer, player that works under Linux, Solaris, BSD and any other Operational System that has Java Runtime Environment 1.4 or later installed.

i.File is a file manager for Linux written for the Windows refugees that are arriving in Linux only to find that the state of the user interface is rather poor. I personally somewhat fall into this catagory, although more as a power user than the average Joe.
Both the leading file managers for KDE and Gnome are well... not to put too fine a point on it: crap. There are just not ready for everyday use by normal people, because of the untold number of bugs in the usability and function that are STILL there 3 years after they first infested Linux desktops.
Not that this project will start off any better, but my hope is that itll end far more successfully than the aforementioned software. i.File project is targetted at other developers in an attempt to get some help with bringing it up to speed. Enough of the basic code layout and implementation is done so that the user can see how things should work. And now its just time to fill in the blanks and bust those bugs.
Main features:
- Be fast. i.File doesnt load icons for every file by its mime type. Because that takes too long. All the algorithms are designed to make it fast. The use of hashtables is pervasive. At no point should "eye candy" ever take precedence over speed. Startup/shutdown time should be sub-second. Drag and drop should have latencies around 100ms at most.
- All views of the same inode (file/dir/etc) point back to the same object, thus when the object changes, all views of that automatically update.
- Network accesses and all other tasks that can take time should be threaded. There is no excuse for locking up the GUI thread while the application goes off to get some data.
- Be minimal. i.File is not a thumb nail viewer, or any other type of viewer. Applications do the viewing, not the file manager. Viewing tasks bloat up the file manager.
- Every file is typed with a mime type. This is marginally better than using a files extension to associate it with an application.
- The Win2k implementation of Windows Explorer is the basis for some of the user interface because it works, people are used to it, and its "the standard". And no the experiments with file manager UI in Linux didnt work. They suck badly, thats why there is i.File in the first place.