What is the unistd symbolic constant for the standard input?STDIN_FILENOSTDOUT_FILENOSTDERR_FILENO

The unistd symbolic constant for the standard input is STDIN_FILENO.

Here’s a quick overview of the constants you mentioned:

1. STDIN_FILENO: This constant represents the file descriptor for the standard input stream, which is typically associated with the keyboard input in a terminal.
2. STDOUT_FILENO: This constant represents the file descriptor for the standard output stream, which is used for outputting data to the console or terminal.
3. STDERR_FILENO: This constant represents the file descriptor for the standard error stream, which is used for outputting error messages.

In most Unix-like systems, these constants are defined in the <unistd.h> header file, facilitating input and output operations in applications.