Using console commands in python

Question

I am using console commands in python, however, it is not outputting the value I want.

The path is:

#ifconfig -a | grep "HWaddr"

From this command I get:

eth0     Link encap:Ethernet HWaddr 30:9E:D5:C7:1z:EF
eth1     Link encap:Ethernet HWaddr 30:0E:95:97:0A:F0

I need to use console commands to retrieve that value, so this is what I have so far for code:

def getmac():
    mac=subprocess.check_output('ifconfig -a | grep "HWaddr"')
print "%s" %(mac)

I basically only want to retrieve the hardware address which is 30:0E:D5:C7:1A:F0. My code above doesn't retrieve that. My question is how do I use console commands to get the value I want.

Thanks in advance.

score 1 · Answer 1 · answered Jun 08 '16 at 04:17

1

The most robust and easy way in Linux to get the MAC address is to get it from sysfs, mounted on /sys.

For interface etho, the location would be /sys/class/net/eth0/address; Similarly for eth1, it would be /sys/class/net/eth1/address.

% cat /sys/class/net/eth0/address 
74:d4:35:XX:XX:XX

So, you could just read the file in python too:

with open('/sys/class/net/eth0/address') as f:
    mac_eth0 = f.read().rstrip()

answered Jun 08 '16 at 04:17

heemayl

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I have tried this, but it does not print out the value still – Nikki bee Jun 08 '16 at 04:43
@Nikkibee Are you sure you have used the right interface name? At first check with running the command directly in terminal.. – heemayl Jun 08 '16 at 10:20
@Nikkibee: heemayl's code only fetches the info, it doesn't print it. – PM 2Ring Jun 09 '16 at 01:13

score 1 · Answer 2 · edited May 23 '17 at 10:34

1

Quoting from here.

Python 2.5 includes an uuid implementation which (in at least one version) needs the mac address. You can import the mac finding function into your own code easily:

from uuid import getnode as get_mac
mac = get_mac()

The return value is the mac address as 48 bit integer.

edited May 23 '17 at 10:34

Community

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answered Jun 08 '16 at 04:25

Rahul

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score 0 · Accepted Answer · edited May 23 '17 at 12:26

import subprocess

def getmac(command):
    return subprocess.check_output(command, shell=True)

command = "ifconfig -a | grep HWaddr" 
print "%s" %(getmac(command).split()[9])
# or print out the entire list to see which index your HWAddr corresponds to
# print "%s" %(getmac(command).split())

Or as per user heemayl,

command = "cat /sys/class/net/eth1/address"
print "%s" %(getmac(command))

Note:
1. Using shell=True isn't recommended as per Python docs
2. This isn't as efficient compared to the normal ways of reading a file in Python.

You could have also returned

subprocess.check_output(command)

However, in the above case, you might get an OSError or a CalledProcessError(retcode, cmd, output=output) depending on whether you passed your commands as a list, which can be solved if you explicitly mention your python path as per this

Reading a (pseudo) file with `cat` in a `subprocess` is _very_ inefficient compared to the normal ways of reading a file in Python file. — PM 2Ring, Jun 09 '16 at 01:23
Sure it isn't as efficient! The OP wanted to use console commands in python, hence the answer. I have edited my answer to include that fact. — Jomy, Jun 09 '16 at 04:48

Using console commands in python

3 Answers3