Set MAC as variable with GREP

dafuzzbudd · 05-21-2009, 11:00 AM

Im writing a bas hscript and im trying to get the user's MAC as a variable. I think this can be done with GREP. The macchanger command outputs "Your MAC is 00:00:00:00:00:00"

Is this possible? Thanks guys.

paulsm4 · 05-21-2009, 12:38 PM

Hi -

There are several ways you can go. Here's one quick'n'dirty alternative:

Code:

/sbin/ifconfig|awk '/HWaddr/ {print}'
eth0      Link encap:Ethernet  HWaddr 00:40:F6:2C:6B:CC

/sbin/ifconfig|awk '/HWaddr/ {print $5}'
00:40:F6:2C:6B:CC

Statement two becomes:

Code:

MAC=`/sbin/ifconfig|awk '/HWaddr/ {print $5}'`
echo My MAC address is $MAC...
My MAC address is 00:40:F6:2C:6B:CC

dafuzzbudd · 05-21-2009, 07:22 PM

nice, thank you very much. i added my interface to the ifconfig line to get the specific MAC.

i don't exactly understand the syntax, can you quickly explain it for me please?

paulsm4 · 05-21-2009, 07:32 PM

Hi, sure -

1. I happen to use "awk" instead of "grep".

2. I get the MAC address from this command:

Quote:

/sbin/ifconfig
eth0 Link encap:Ethernet HWaddr 00:40:F6:2C:6B:CC
inet addr:192.168.1.150 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:399879 errors:0 dropped:10 overruns:0 frame:0
TX packets:30434 errors:1 dropped:0 overruns:1 carrier:0
collisions:2749 txqueuelen:100
Interrupt:10 Base address:0xe800

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:3924 Metric:1
RX packets:74159 errors:0 dropped:0 overruns:0 frame:0
TX packets:74159 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0

3. "awk" does two things:
a) This finds the line(s) that match "HWaddr" (much like "grep"):

Quote:

awk ... /HWaddr/

b) This prints column 5 of the matching line(s):

Quote:

awk ... {print $5}

'Hope that helps .. PSM
PS:
Please feel free to click the little blue "thumbs up" icon if this was useful.

dafuzzbudd · 05-22-2009, 08:33 AM

thanks for the explanation

sometimes the MAC sets to 12:23:45:67:78:89:00:00:00:00:00:00
is there any way to take the first 17 characters?

i looked up the options for awk and when i seeing some of the instructions linked together my head starts to spin.

ghostdog74 · 05-22-2009, 09:12 AM

Quote:

Originally Posted by dafuzzbudd

i looked up the options for awk and when i seeing some of the instructions linked together my head starts to spin.

see here for substr() function. head starting to spin is not an excuse for not trying. My head hurts too when i first used awk.

paulsm4 · 05-22-2009, 11:07 AM

Hi -

In Linux generally, if you can imagine it, you can do it. Usually in many different ways - you get to pick your favorite ;-)

ANYWAY:
Ghostdog is correct. The awk "substr()" function is probably the best way to get the left 17 characters from a string. "printf ("%-17s", $1)" might be another way.

Here's a nice, relatively painless tutorial on "awk". It barely scratches the surface - but it'll get you started:

http://www.oracle.com/technology/pub...laney_awk.html

Thanx for the "thumbs up", too. Deeply appreciated!

Sincerely .. PSM