Tag Archives: Ubuntu 12.04

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