Program that copies command output to the clipboard

xsel is a linux GNU tool used to copy command line output or file output to your standard clip board for pasting.

http://linuxtidbits.wordpress.com/2008/02/22/command-line-to-clipboard/

To copy a text to the middle mouse button clipboard:

xsel < /etc/fstab

To copy to the context-menu clipboard:

xsel --clipboard < /etc/fstab

Also Xsel can be piped to:

echo “a-bit-of-text” | xsel -c
cat /etc/make.conf | xsel -c

Paste

To output clipboard information to the terminal:

xsel --clipboard

Its just as easy to output clipboard information to a file:
xsel --clipboard > Baada-Boom.txt

To append the information:

xsel --clipboard >> ~/.bashrc