1. What are file descriptors?
   A handle to files or devices used by Linux as an interface for input/output.
2. What do the terms stdin, stdout and stderr mean?
   • stdin, standard input. Used for input to commands.
   • stdout, standard output. Used for normal output of commands.
   • stderr, standard error. Used for error output of commands.
3. How to stdin, stdout and stderr map to the default file descriptors?
   stdin is bound to fd0, stdout to fd1, and stderr to fd2.
4. What is the difference between the output redirections >, 1> and 2>?
   > and 1> are equal, and refer to redirecting stdout. 2> is used to redirect stderr.
5. What is the difference between > and >>?
   > will overwrite the file if it already has content, while >> will append to the file.
6. How can both stdout and stderr be redirected at the same time?
   • By using &> (and &>>)
   • By binding stderr to stdout, using 2>&1
   • By piping with |&
7. Which special devices can be used to act as a black hole for output?
   /dev/null and /dev/zero.
8. What does a pipe do, with regards to redirections?
   It binds the stdout/stderr of a command to the stdin of another command.
9. How can we send output to both the terminal and a log file?
   By piping through the tee command, preferably with |& so both stdout and stderr is forwarded.
10. What is a typical use-case for a here string?
    We can use a here string if we want to supply input directly to stdin of a command. bc is a good example of this.