copy line to new file if word matches

I'm drawing blank on this. The log file I have is filled with garbage, but the important lines are ##/##/### Installation xxxxxxx
So, I want to sed the line to a new file IF the word installation is in it.
I tried removing none matching lines

sed 's/Installation/,//!d' infile > outfile

but that didn't work.

If you want to select the lines with "Installation":

egrep 'Installation' input_file

Hi,

Something like this using 'sed':

$ sed -ne '/installation/Iw outfile' infile

Regards,
Birei

awk '/Installation/' input_file