Category Archives: TIPS ‘N’ TRICKS

System.getProperty(key) key list for java:

 







java.version
Java Runtime Environment version




java.vendor
Java Runtime Environment vendor




java.vendor.url
Java vendor URL




java.home
Java installation directory




java.vm.specification.version
Java Virtual Machine specification version




java.vm.specification.vendor
Java Virtual Machine specification vendor




java.vm.specification.name
Java Virtual Machine specification name




java.vm.version
Java Virtual Machine implementation version




java.vm.vendor
Java Virtual Machine implementation vendor




java.vm.name
Java Virtual Machine implementation name




java.specification.version
Java Runtime Environment specification version




java.specification.vendor
Java Runtime Environment specification vendor




java.specification.name
Java Runtime Environment specification name




java.class.version
Java class format version number




java.class.path
Java class path




java.library.path
List of paths to search when loading libraries




java.io.tmpdir
Default temp file path




java.compiler
Name of JIT compiler to use




java.ext.dirs
Path of extension directory or directories




os.name
Operating system name




os.arch
Operating system architecture




os.version
Operating system version




file.separator
File separator (“/” on UNIX)




path.separator
Path separator (“:” on UNIX)




line.separator
Line separator (“\n” on UNIX)




user.name
User’s account name




user.home
User’s home directory




user.dir
User’s current working directory








 

					

			
						

	
	


				
					

				
					


	

		
Sudoers – Community Ubuntu Documentation
	


	

		

				
Shutting Down From The Console Without A Password


Often people want to be able to shut their computers down without requiring a password to do so. This is particularly useful in media PCs where you want to be able to use the shutdown command in the media centre to shutdown the whole computer.


To do this you need to add some cmnd aliases as follows:


Cmnd_Alias SHUTDOWN_CMDS = /sbin/shutdown, /sbin/halt, /sbin/reboot


You also need to add a user specification (at the end of the file after the “%admin ALL = (ALL) ALL” line so it takes effect – see above for details):


ALL=(ALL) NOPASSWD: SHUTDOWN_CMDS


Obviously you need to replace “” with the username of the user who needs to be able to shutdown the pc without a password. You can use a user alias here as normal.


via Sudoers – Community Ubuntu Documentation.

			

	
	


				
					


	

		
How to convert flv to mp3 in Ubuntu
	


	

		

				
FFmpeg from the repository is not compiled to support restricted formats such as mp3. You can use a third-party repository such as Medibuntu, compile ffmpeg yourself, or use another library, such as: libavcodec-extra-53.


The basic command:




Code:


ffmpeg -i inpuvvideofile.flv outputaudiofile.mp3




By default this will create a 64 kb/s file. You can declare the audio bitrate with -ab:




Code:


ffmpeg -i inpuvvideofile.flv -ab 128k outputaudiofile.mp3




If the flv already has mp3 audio, then there is no need to re-encode. You can just copy the audio stream. This will preserve the audio quality and will be much quicker since there is no re-encoding:




Code:


ffmpeg -i inpuvvideofile.flv -acodec copy outputaudiofile.mp3




Don’t know what the audio is? Just ask ffmpeg:




Code:


ffmpeg -i inputvideo.flv




Along with some other information, ffmpeg will provide file details with the above command:




Code:


Stream #0.0: Video: flv, yuv420p, 320x240, 29.97 tb(r)
Stream #0.1: Audio: mp3, 22050 Hz, mono, s16, 56 kb/s

Source:ubuntuforums.org/showthread.php?t=852027