Section 9.5. Standard Files

9.5. Standard Files

There are generally three standard files that are made available to you when your program starts. These are standard input (usually the keyboard), standard output (buffered output to the monitor or display), and standard error (unbuffered output to the screen). (The "buffered" or "unbuffered" output refers to that third argument to open()). These files are named stdin, stdout, and stderr and take their names from the C language. When we say these files are "available to you when your program starts," that means that these files are pre-opened for you, and access to these files may commence once you have their file handles.

Python makes these file handles available to you from the sys module. Once you import sys, you have access to these files as sys.stdin, sys.stdout, and sys.stderr. The print statement normally outputs to sys.stdout while the raw_input() built-in function receives its input from sys.stdin.

Just remember that since sys.* are files, you have to manage the line separation characters. The print statement has the built-in feature of automatically adding one to the end of a string to output.