Can you run a Python program using Nice in Mac Terminal?

Question

I'm trying to assign a high priority level to a Python program as soon as it runs using Terminal. I'm thinking of syntax along the lines of:

sudo nice -n -20 pythonfile.py

This returns the error: no such file. However,

python pythonfile.py

works just fine so the file certainly exists. The only other examples on the internet that I've seen are shell files ending in sh, such as

sudo nice -n -20 ./test.sh

But I want to be able to do this for a Python file. Incidentally I can get this apply to an already running python program using renice but I want to be able to assign a high priority to the task from the get go.

Answer 1

It doesn't matter whether you're running a shell script or a Python script, and it doesn't even matter whether you're using sudo and/or nice or not. The final syntax is still the same, as long as you pay attention to what command you are running – that is, whether you are explicitly calling an interpreter or whether you're directly running the script as a program.

In your working example, you are running python as the actual program, and the script's name is just a parameter. This works because the 'python' program is automatically found through $PATH.

python myscript.py
bash myscript.sh
node myscript.js

In your non-working example, you didn't specify the interpreter, so instead the script itself becomes the command to execute. The system again tries to find it through $PATH and fails. To make it work, you must specify where the script or program is located.

Note how the example you found for shellscripts specifies the directory in which the script is located (that's the ./ part, meaning "current directory").

./myscript.py
./myscript.sh
./myscript.rb

(Also note: Because you aren't telling the system which interpreter to use, the script's 1st line must do that instead. Usually it should say #!/usr/bin/env python.)

So the answer is, both sudo and nice follow exactly the same rules described above as regular commands. For example, you can run the script like this:

python myscript.py
sudo python myscript.py
nice -n -20 node myscript.js
sudo nice -n -20 bash myscript.sh

Same goes for the direct script invocation:

./test.py
sudo ./test.pl
nice -n -20 ./test.js
sudo nice -n -20 ./test.sh