Python · OS, sys, argparse & subprocess

You're about to pack binary data and need to know whether the host stores the most significant byte first. Which sys value tells you, and what are its two possible values?

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More in OS, sys, argparse & subprocess

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What does `r.stdout` hold after this, and why is `text=True` important? ``` r = subprocess.run( ["echo", "hi"], capture_output=True, text=True) ```

What are sys.stdin, sys.stdout, and sys.stderr, and why send error/diagnostic messages to stderr rather than stdout?

You read a config value with os.environ["API_KEY"]. It works on your machine but crashes with KeyError on a fresh deploy where the var isn't set. What's the safe way to read it?

What does this print when run as `python prog.py hello`? ``` import sys print(len(sys.argv)) print(sys.argv[0]) ```

A script is called `python add.py 2 3` with this body. What does it print? ``` import sys print(sys.argv[1] + sys.argv[2]) ```

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