240 – Open standard input

240 – Open standard input#

The built-in function open can accept integer file descriptors, which means you can read from stdin by using open(0)! Suppose you have a short text file called fox.txt:

The quick brown fox
jumps over the lazy dog.

And you also have a short Python script, called reader.py, that prints the first line from stdin:

with open(0) as f:
    print(f.readline())

Now, if you run the script reader.py and pipe in the contents of fox.txt, you get the first line of the text file:

$ python reader.py < fox.txt

The quick brown fox