Three standard streams: stdin, stdout, and stderr play a fundamental role in handling input and output operations.

What are stdin, stdout, and stderr?

stdin (Standard Input):

• Description: A stream used to read input from the user or another program.
• Common Usage: Reading user input from the terminal or receiving input data in a pipeline.
• Default Source: Keyboard.

stdout (Standard Output):

• Description: A stream used to write regular output data.
• Common Usage: Displaying output to the terminal or sending data to another program in a pipeline.
• Default Destination: Terminal.

stderr (Standard Error):

• Description: A stream used to write error messages and diagnostics.
• Common Usage: Displaying error messages to the terminal or logging errors.
• Default Destination: Terminal.

Redirection

You can redirect stdin, stdout, and stderr to files or other commands in the terminal:

Redirect stdout to a file:

command > output.txt

Redirect stderr to a file:

command 2> error.txt

Redirect both stdout and stderr to a file:

command > output.txt 2>&1

Read input from a file:

command < input.txt

Redirect output from one command to another:

command | command2