Removes all exe files in the current directory tree. Useful to clear virus from flash drives.

find . -name "*.exe" -delete

View first two lines of a file

head -2 file

tail -2 file # for last 2 lines

Repair / check integrity of linux filesystem on disk hda1

fsck  /dev/hda1

View only lines that contain the word “string”

sed -n '/string/p'

Start a download at any given time

echo 'wget -c www.example.com/files.iso' | at 09:00

Update the package list - do this after you change the source in /etc/apt/sources.list .

apt-get update

Get the version of the kernal

cat /proc/version
OR
uname -r