Learn Linux Shell Scripting - Fundamentals of Bash 4.4

Chapter 12

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.