This short article teaches you 4 common switches to use in the command line with Python.
The Python 🐍 command has many different switches.
Here are the 4 switches I use the most:
-c cmd: program passed in as string;
-m mod: run library module as a script;
-i: inspect interactively after running script; and
-q: don't print version and copyright messages on interactive startup.
-c runs code directly from the command line.
It doesn't open the REPL, and it is convenient for short, one-off expressions.
The result isn't printed by default, so don't forget your
# What is the factorial of 15? λ python -c "import math; print(math.factorial(15))" 1307674368000 # What is 2 + 2? λ python -c "print(2 + 2)" 4
-m runs a module as a script.
This will run an installed module's section that is inside
if __name__ == "__main__":.
The one I use the most is the module
timeit to measure execution time:
λ python -m timeit -s "import math" "math.factorial(15)" 2000000 loops, best of 5: 167 nsec per loop λ python -m timeit -s "import math" "math.factorial(150)" 200000 loops, best of 5: 1.52 usec per loop
-i stands for Inspect Interactively.
By running your code with
-i, after the script is done,
you get a REPL session with the variables and functions from that script.
Useful to play around with functions you just defined.
Suppose this is your file
x = 3 y = 5 def add(x, y): return x + y
If you run it with
-i, you get to play around with the variables
y and with the function
λ python -i example.py >>> x 3 >>> y 5 >>> add(x, 10) 13
-q opens the REPL Quietly.
What this means is that it opens the REPL without displaying all the version/platform information.
I use it when recording videos and demoing things.
λ python -q >>> # This is a standard REPL
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