How to substitute a variable taken from the list in the file into the URL?

Question

bash

There is a line-by-line list of users in a text file.
user1
user2
..
userN

There is an API that, when requested, curl http://address.ru/api/user1/returns various information about the user (in this case, user1 in this case) in json format.
How to make a script that will take the username line by line from the users.txt file, substitute it in curl and write the response line by line to another out.txt file?

Answer 1

Yes, everything seems to be simple to the point of banality, isn't it?

for user in $(cat in.txt); do
  curl -s "http://address.ru/api/$user/" >> out.txt
done