Bash Pipe Handling

Question

Does anyone know how bash handles sending data through pipes?

cat file.txt | tail -20

Does this command print all the contents of file.txt

Answer 1

cat will just print the data to standard out, which happens to be redirected to the standard in of tail. This can be seen in the man page of bash.

In other words, there is no pausing going on, tail is just reading from standard in and cat is just writing to standard out.