#extracts the ip address from ifconfig

/sbin/ifconfig  sed -e 's/[^i]*inet addr:\([0-9.]*\).*/\1/p' -e d 

#extracts email addresses

tr '\t' '\n' < custemail.txt | grep '.*@.*'

# also extracts email addresses

awk '/@/ { s = $0; while (match(s, /[^ ]+@[^ ]+/) > 0) {
print substr(s, RSTART, RLENGTH); s = substr(s, RSTART + RLENGTH) } }' 

# dont forget sort and uniq to remove duplicate lines in a file