Really do appreciate your help guys am now starting to get a grip on bash but not quite......

suppose i have a statement

fileA....
Foot is a word we can use in all aspects of our life and has several meanings.part of it can a foot pedal or rather in football as well.


i want to use sed to replace just the word 'foot' nothing more and when it ats the begining of a line replace with caps.......if i wanted to replace it with say play.....this becomes

Play is a word we can use in all aspects of our life and has several meanings.part of it can a play pedal or rather in playball as well.

been trying this

#!/bin/bash

IFS=$'\n'


for i in $(cat fileA);
do
echo $i | sed -r 's/^[foot]^/play:g' >> fileB
done

i have tried this but words like football r being affected i need football to remain unchanged only change foot where the word is not part of another word

How about just adding a space or two...:

Thanx!!! that seems to do the trick...is there any way i can improve it to say for example notify me that there is a similar word but it is part of another word?

You are getting outside the realm of what sed can reasonably do. At this point I would probably switch to Perl.

This should handle full stop and other punctuation, which the sed script won't (without additional tinkering).