Python Question: Correct way to get stdout as variable and use in a system call?

[vailixi]

I'm trying to get the output of a command as a variable and use it for a system call. Mostly I'm trying to get the concept of this by doing something easy like changing a MAC address.
Firstly I want to get the wireless interface. I know I can make <iface> a command line option and I'm sure that's a better way to go but it's not really the point.

There are several ways to get the wireless interface. Some of the stuff I tried.

cat /proc/net/wireless | tail -n 1 | cut -d ' ' -f 2 | tr -d ':' | sed '/^\s*$/d' #this method is completely unreliable

ifconfig | tail | head -2 |  sed '/^\s*$/d' | cut -d ":" -f 1 #this seems to work

ip link show | tail -n 2 | head -n 1 | cut -d ':' -f 2 | cut -d ' ' -f 2 #maybe

Then I tried iwfconfig I think it is several outputs instead of one. So head, tail, and grep don't seem to work on it. I tried readarray as well. I didn't want to write to a file then cat the file into read array or read the file from the python script because usually there is a more elegant way of doing things. I just don't know how to do it.

Question is there a more elegant way of doing this stuff?

import subprocess
from subprocess import call

batcmd="cat /proc/net/wireless | tail -n 1 | cut -d ' ' -f 2 | tr -d ':'"
wlan = subprocess.check_output(batcmd.strip(), shell=True)
print(wlan).strip()

call(["ifconfig", wlan.strip(), "down"])
call(["macchanger", "-r", wlan.strip()])
call(["ifconfig",  wlan.strip(), "up"])

I tried this and it works sometimes. But sometimes fails because cat fails to return the wireless interface.

import subprocess
from subprocess import call

batcmd="ifconfig | tail | head -2 |  sed '/^\s*$/d' | cut -d ':' -f 1"
wlan = subprocess.check_output(batcmd.strip(), shell=True)
print(wlan).strip()

call(["ifconfig", wlan.strip(), "down"])
call(["macchanger", "-r", wlan.strip()])
call(["ifconfig",  wlan.strip(), "up"])

I wasn't sure if subprocess is the best of way of doing this. What I really need is ways to get stdout and use it in a system call.

Edited October 12, 2018 by vailixi

[i8igmac]

I would use 'iw dev' (i think)all of the linux wireless networking software is a wrapper of `iw`
 

iw dev |grep -i grep interface.

 

System('iw dev'){ |line| 

   if line include?('interface')

      puts line.split[1] #=> wlan

   End

End

 

Just a ruby snip. what if you have multiple wireless interfaces. I would assume you don't want the one associated with a access point. So further system variable checks would need to be made...

 

I'm unsure of your plan. Automatic wifi attacks? 

[vailixi]

iw dev |grep -i interface | cut -d ' ' -f 2

Perfect. Thanks.

Actually there are plenty of automated wireless attack scripts available already. I'm trying to learn how to code deeper system automation. I need to be able to deal with outputs. I started working with python because python is easy compared to other languages. I'll probably port some of my BASH scripts over to python once I get a better handle on that. It seems to be what the cool kids are doing.

Edited October 12, 2018 by vailixi

[i8igmac]

if your learning python. don't use bash or pipes to grep your information. Get the information you need with python.

 

System('Iw dev'){ |input,output,thread|
   write.input('type yes to save')

   print(output)

   Print thread.pid.info

      If thread.poop then

          thread.kill.pid

      End

}
 

 

This code is generic. check if python has a lib popen3. Write to stdin, read stdout, get pid and thread information. Use python to get the information you need.

Edited October 13, 2018 by i8igmac