How to create the file?

You can create the file usernames.txt in the /home/labex/project/ directory using the following command in the terminal:

touch /home/labex/project/usernames.txt

Alternatively, you can create and open the file for editing using a text editor like nano or vim:

Using nano:

nano /home/labex/project/usernames.txt

Using vim:

vim /home/labex/project/usernames.txt

After running any of these commands, you can add content to the file and save it. If you're using nano, you can save and exit by pressing CTRL + X, then Y to confirm, and Enter to save. In vim, you can save and exit by pressing Esc, typing :wq, and then pressing Enter.