Display number of processors

Use:

cat /proc/cpuinfo | grep processor | wc -l

Source: http://www.howtogeek.com/howto/ubuntu/display-number-of-processors-on-linux/

Update PDF metadata

From http://askubuntu.com/questions/401114/which-is-the-best-pdf-metadata-viewer-for-ubuntu

1. View pdf metadata for a file called Example.pdf:
   

   pdfinfo Example.pdf  
   

2. Edit existing metadata in the terminal using nano editor:
   

   pdftk Example.pdf dump_data output Metadata-output.txt
   nano Metadata-output.txt  
   

3. Update metadata:
   

   pdftk Example.pdf update_info Metadata-output.txt output Example-new.pdf 

Problem: “WARNING: untrusted versions of the following packages will be installed!”

sudo apt-get clean
sudo rm -rf /var/lib/apt/lists/*
sudo apt-get clean
sudo apt-get update 

Solution from: http://serverfault.com/questions/444798/debian-warning-untrusted-versions-of-the-following-packages-will-be-installe 

Problems with bluetooth file transfer

"gdbus.error.org.bluez.obex.error.failed" "unable to find service record"

Try killing obexd

To configure cheese and other applications

Use dconf-editor

To install XCTU (Windows version) on Linux

This is a good tutorial about this.. https://github.com/TauLabs/TauLabs/wiki/Xbee-Programming-on-Linux

However, this is no longer needed because XBee has a Linux version now :D

Anyway, I post this because I think it could help to install other similar windows-based software which needs to connect with usb (serial) ports.

Solution for the problem "skype: error while loading shared libraries: libGL.so.1: cannot open shared object file: No such file or directory"

Source: http://askubuntu.com/questions/555902/problems-after-installing-skype-4-3

Execute: 

LD_PRELOAD=/usr/lib/i386-linux-gnu/mesa/libGL.so.1 skype