If you want to delete a user and chown all files that belong to this user, you can use this command:

sudo chown -R --from=username newowner /

grep (case-insensitive, recursive) grep doesn't offer any possibility to recursively descent down the directory tree. The following command searches e.g. just thru all the files in the current directory:

grep bacteria *

To make the search case-insensitive, one can use the i flag:

grep -i bacteria *

But if you want to do a recursive search you have to use a quite complicated construction of UNIX commands to achieve this goal:

find ~/Mail -type f -exec grep 'bacteria' {} \; -print

In order to copy the file index.html from the local machine to vesuri.helsinki.fi the following command is needed:

scp -p /Volumes/Documents/michael/Sites/index.html mjeltsch@vesuri.helsinki.fi:./public_html/index.html

The full path of the original file (/Volumes/Documents/michael/Sites/index.html) is of course not needed if the file is in the current directory.

To find files in the current directory and its subdirectories that have been modified (= created or updated) 2 minutes ago
find . -cmin 2 To find files in the current directory and its subdirectories that have been modified (= created or updated) within the last 2 minutes find . -cmin -2