I have many of this similar lines in a file and it is always start with number 7. How can replace this Whole-Line with something that I want.

7 ;0;12 ;3;0; ; ; ;ABCD ;n;n; ; ; ; ; ;

I tried:

sed 's/^7/tom/g' file

I get:

tom ;0;12 ;3;0; ; ; ;ABCD ;n;n; ; ; ; ; ;

Also,

there are lines that may start with 70, 71,.....79. How can I make it works for just "7"

For example:
79 ;0;12 ;3;0; ; ; ;ABCD ;n;n; ; ; ; ; ;

I will get:
tom9 ;0;12 ;3;0; ; ; ;ABCD ;n;n; ; ; ; ; ;

Many Thanks!

sed 's/^7 ;.*$/tom/' < infile > outfile

Thank you for the reply! but it is not working!

replace whole line?

Thanks! It works!

No it doesn't.

You said
The sed command given will also replace entire lines starting with 70, 71, 79 - whatever, e.g.
Are you sure this is what you want?