pipe output of ls to echo to append prefix to list

Question

I am trying to pipe data to split in a bash script. I have a directory that consists of

a.txt
b.txt
c.txt
...

I would like to make a summary file that lists these files in batches of a thousand. The following gets me close

ls *.txt | sort | split -l 1000

My problem is I want it to look like

file a.txt
file b.txt 
etc...

my plan was to add an echo file ???? in there to make that happen but I cannot pipe ls to echo

Any ideas

Answer 1

Don't parse the result of ls, you might better do something like this:

find ./ -maxdepth 1 -name "*.txt" -exec echo "file" {} \; | sort