UNIX for Advanced & Expert Users

Hello All,

Could you please provide the solution to my following query
I have some files in my directory. I need to amend the total number of
lines to be added in the starting
line of each file.

For example, please refer the content of the file "file.dat" below.

\h:\w #> cat file.dat
hai
hello
end
Nice day
\h:\w #>

After your command, the output should be below.

\h:\w #> cat file.dat
Total no. of lines: 4
hai
hello
end
Nice day
\h:\w #>

We can do this in sed and awk through a single command. But we will
avoid the sed and awk stuff's for some time.
and can just try using simple unix commands for now.

Regards,
Sandeep

This is homework. Please do not post homework.