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#!/usr/bin/env python3

from subprocess import run
from sys import modules

def main():
  doas()

def doas():
  ch = input("Ready to proceed with setting up doas?[Y/n]?")
  if ch == 'y':
    run("sudo passwd", shell=True)#If you would prefer to access the root account with su or by logging in directly, you must set a root password with "sudo passwd".
    run("sudo apt install -y doas", shell=True) 
    run("""echo -e "permit $(whoami) as root 
permit root as $(whoami)
permit nopass root as $(whoami)"|sudo tee /etc/doas.conf""", shell=True) and run("doas apt -y purge sudo", shell=True)
    print("doas set up.")
  else:
    print("Run me again when you are ready.")

The problem with this code is that it places the option -e in doas.conf, like so:

-e permit jim as root
permit root as jim
permit nopass root as jim

while I need doas.conf to look like so:

permit jim as root
permit root as jim
permit nopass root as jim

I know that the easiest quick fix is simply not to use -e with echo. Is there any other way I can resolve this issue?

Why does -e end up written into doas.conf if it is not enclosed within double quotes? When I run

echo -e "permit $(whoami) as root 
permit root as $(whoami)
permit nopass root as $(whoami)"|tee doas.conf

from my shell (Bash), then all works fine and I get the desired result. Why is it different from Python? I'm on Ubuntu 22.04 LTS, and my echo seems to support -e, e.g. echo -e "a\nb\nc" it prints them letters with newlines.

John Smith
  • 753

1 Answers1

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Because different implementations of echo either support or don't support options like -e and -n, and either process or don't process C-style backslash-escapes like \n and \t.

A standard echo does not take options:

The echo utility shall not recognize the "--" argument in the manner specified by Guideline 10 of XBD Utility Syntax Guidelines; "--" shall be recognized as a string operand.

Implementations shall not support any options.

Use printf instead. See: Why is printf better than echo?

Quotes (double or single) have nothing to do with it, as they are processed by the shell before the command runs and gets a chance to process its options. In all of

echo -e foo
echo "-e" foo
echo '-e' foo

the echo command sees the two arguments -e and foo.

ilkkachu
  • 138,973
  • I'm on Ubuntu 22.04 LTS, and my echo seems to support -e, e.g. echo -e "a\nb\nc" it prints them letters with newlines. – John Smith May 22 '23 at 08:24
  • @JohnSmith, well. The one that your Python script starts obviously doesn't. The point is that there's no single echo, but that every implementation is potentially different. So, don't use echo if you care about the output being what you want, there's a better and more compatible alternative available in printf. – ilkkachu May 22 '23 at 08:37
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    @JohnSmith, if you want to go there, you probably have not one, but three echo implementations on Ubuntu: the one in Bash, the one in Dash, and the one in /bin/echo. And yes, they're all different. – ilkkachu May 22 '23 at 08:39
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    @ilkkachu four, with busybox usually being installed by default too. – muru May 22 '23 at 09:54