How Linux I/O Redirection Works: Understanding File Descriptors and Streams

In Unix-based systems, everything is treated as a file, including input and output streams such as stdin, stdout, and stderr, which are assigned file descriptors 0, 1, and 2 respectively. By default, stdout displays program output on the screen and stdin reads from the keyboard, but these destinations can be changed using redirection operators. The '>' operator redirects stdout to a file, overwriting it, while '>>' appends to an existing file without erasing its contents. To capture error output separately, the file descriptor notation '2>' is used, and both stdout and stderr can be combined into a single destination using '&>' or the traditional '2>&1' syntax. Unwanted output can be silently discarded by redirecting streams to '/dev/null', a special system file that discards all data written to it.