===== Extract Email Address =====
The file abc.af looks like this:
<file>
R1211566974^M
F<fettle@333empire.com>^M
T<gwensadler@vp.dk>^M
</file>

The following extracts the two email addresses:

<code>
cat abc.af |perl -wne'while(/[\w\.\-]+@[\w\.\-]+\w+/g){print "$&\n"}'
fettle@333empire.com
gwensadler@vp.dk
</code>

===== Making a list one line =====
If you have a list in a textfile:
<file>
abd
def
ghi
</file>

You want to make into:
<file>
abc def ghi
</file>

Do this:
<code>
cat /tmp/textfile |tr "\n" " " > /tmp/textfile.withoutnewlines.txt
</code>

This command substitute newlines ("\n") with spaces (" ") and send it to the file textfile.withoutnewlines.txt


===== Extract FQDN from URL =====

<code>
tdd@host:~/bin$ echo "http://domain.tdl/xx.?=0/ff" |awk -F '/' '{print $3}'
domain.tdl
tdd@host:~/bin$ 
</code>