How to print some free text in addition to SED extract - sed

Question

Well-known SED command to extract a first line and print to another file
sed -n '1 p' /p/raw.txt | cat >> /p/001.txt ;
gives an output in /p/001.txt like
John Doe
But how to modify this command above to add some free text and have, for example, the output like
Name: John Doe
Thanks for any hint to try.

Answer 1

You can do that in a single command (and no sub-shells):
sed 's/^/Name: /;q' /p/raw.txt >> /p/001.txt
This prefixes "Name: " in front of the first line, prints it, then quits so you don't process additional lines. Add a line number before the q to print all lines up to (and including) that number. The output is appended to /p/001.txt just like your original code.
If you want a range of lines:
sed -n '3,9{s/^/Name: /;p}9q' /p/raw.txt >> /p/001.txt
This reads from lines 3-9, performs the substitution, prints, then quits after line 9.
If you want specific lines, I recommend awk:
awk 'NR==3 || NR==9 { print "Name: " $0 } NR>=9 { exit }' /p/raw.txt >> /p/001.txt
This has two clauses. One says the number of record (line number) is either 3 or 9, in which case we print the prefix and the line. The other tells us to stop reading the file after the 9th record.
Here are two more commands to show how awk can act on just the first line(s) or a given range:
awk '{ print "Name: " $0 } NR >= 1 { exit }' /p/raw.txt >> /p/001.txt
awk '3 <= NR { print "Name: " $0 } NR >= 9 { exit }' /p/raw.txt >> /p/001.txt
It appears you're continuously building one file from the other. Consider:
tail -Fn0 /p/raw.txt |sed 's/^/Name: /' >> /p/001.txt
This will run continuously, adding only new entries (added after the command is run) to /p/001.txt
Perhaps you have lots of duplicates to resolve?
awk 'NR != FNR { $0 = "Name: " $0 } !s[$0]++' \
/p/001.txt /p/raw.txt > /tmp/001.txt && mv /tmp/001.txt /p/001.txt
This folds together the previously saved names with any new names, printing names only once (!s[$0]++ is true when s[$0] is zero (its default state), but after the evaluation, it increments to one, making it false on the second occurrence. When a bare clause has no action, the line is printed.) Because we're reading the output file, we need a temporary output. Upon its successful completion, we then move it atop the target output file.

Answer 2

printf "Name : %s\n" "$(sed -n '1p;q' /p/raw.txt)" >/p/001.txt
should do it. If sed is not a requirement do
echo -e "Name : $(sed -n '1p;q' /p/raw.txt)" >/p/001.txt
Note
The q option with the sed quits it without processing any more commands or input.
The -e option tells echo to interpret escape sequences. This is a peculiarity of bash shell.