UNIX for Dummies Questions & Answers

I'm trying to create a header row that contains the filename of a file for all columns.

e.g.
file1.txt

first middle last
1 2 3
4 5 6

desired output file should be:
file1 file1 file1
first middle last
1 2 3
4 5 6

my code is:

Code:

for file in *.txt; do echo "$file"\t"$file"\t"$file" >> $file;done

Result is:
first middle last
1 2 3
4 5 6
file1 file1 file1 (all in the first column)

All help is much appreciated!

Code:

for file in *txt
do
  sed -i.bak '1 i "$file $file $file"' *txt
done

Code:

awk 'NR==1{print FILENAME,FILENAME,FILENAME RS $0} NR>1 ' $file > temp
mv temp $file

This code ended up adding 2 rows to my file
$file $file $file
$file $file $file
first middle last
1 2 3
4 5 6

But it helped with tweaking rdcwayx's code for a backup file

rdcwayx: your code worked!

Thanks folks