Searching for a pattern string under a directory

In order to search for a pattern string in all files under a specific directory you can use following command:
find $dir -exec grep $pattern {} \; -print
just replace $dir with the directory you want to start searching in and $patter with patter you are searching for.
for example:
find /etc -exec grep support {} \; -print

changing editor in ubuntu linux

To permanently change editor in Linux do following:
edit your shell configuration file,
for example, bash configuration file is ~/.bashrc
To set editor as VI:
export VISUAL=vi
or to set nano:
export VISUAL=nano
to start it run:
source ~/.bashrc