In the project walkthrough video for step #15 he shows the answer as " sed ‘s/loss/win’ games.txt " however the step says to “sed to replace all instances of the word ‘loss’ with ‘win’ in games.txt.” To do this it would require both the -i option to modify the file and the g flag is required to make the substitution for all non-overlapping matches of the regular expression, not just the first one. This example was used in the sed lesson and the correct solve would be- sed -i ‘s/loss/win/g’ games.txt