Linux freeze on high memory consumption

Sometimes when working with virtual images, R or python, I can see that the memory load is really high and then the system becomes completely unresponsive. This post will show you how to optimize memory management in linux so the system does not freeze.

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Codify video with ffmpeg

To recodify a video with a different codec you can use ffmpeg with the following sintaxis:

ffmpeg -i inputfile -c:v  -c:a  outputfile

Where and are the codecs for video and audio channel to codify the intpu file.

To see all the available codecs write:

ffmpeg -formats

For example to recodify a video into h.264 for video channel and mp3 for audio:

ffmpeg -i input.AVI -c:v h264 -c:a mp3 output.mp4

To codify in mov:

ffmpeg -i input.AVI -acodec aac -ac 1 -ar 44100 -ab 64k -strict -2 -vcodec libx264

How to create a Debian/Ubuntu repository

Create the repository directory with a conf dir inside:
Configure your favourite webserver to publish this repository dir and all its content

$ mkdir -p repo/conf
$ cd repo

Create the file conf/distributions and edit its content:

$ vi conf/distributions
Architectures: i386 amd64 source
Codename: stable
Components: main
Description: Repo description
Label: Ubuntu
Origin: MyOrigin
Version: 12.10

Create the file conf/options and edit its content:

$ vi conf/options
basedir .

Check if the repo is working:

$ reprepro  check
Checking stable...

Create a key with name repokey:

$ gpg --gen--key
$ gpg --export repokey > repokey.gpg

Sign the debian packages with the new key:

$ dpkg-sig --sign repokey ~/packages/*.deb

Copy them to the stable repository:

$ reprepro includedeb stable ~/packages/*.deb

We can see that the repository has the desired packages by writing:

$ reprepro list stable

And that it’s all.
You have finished your new repository.

If you want to remove a package from the stable repository:

$ reprepro remove stable 

If you want to remove all the packages from the stable repository

$ reprepro removefilter precise 'Section'