On Thu, Feb 28, 2008 at 2:56 PM, Max Hetrick maxhetrick@verizon.net wrote:

Toby Bluhm wrote:

...

There's multiple spaces in the output that cut is hitting - use tr to reduce them.

ifconfig | grep eth0 | tr -s ' ' ' ' | cut -d ' ' -f 5

Or:

ifconfig | grep eth0 | cut -d ' ' -f 11

For the sed people, this should also work :

ifconfig | grep eth0 | sed -e "s/^.*HWaddr (.*)$/\1/"

Regards, Tim

On Thu, Feb 28, 2008 at 08:56:49AM -0500, Max Hetrick enlightened us:

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Toby Bluhm wrote:

...

There's multiple spaces in the output that cut is hitting - use tr to reduce them.

ifconfig | grep eth0 | tr -s ' ' ' ' | cut -d ' ' -f 5

Or:

ifconfig | grep eth0 | cut -d ' ' -f 11

Or reduce the number of pipes by one:

ifconfig eth0 | awk '/HWaddr/ { print $5 }'

Matt

On Thu, 2008-02-28 at 08:51 -0500, Toby Bluhm wrote:

Jerry Geis wrote:

...

I am trying to grab the mac address for eth0 on centos 5.1 with

ifconfig | grep eth0 | cut -d ' ' -f 5 and I dont get anything.

What am I not doing right?

ifconfig | grep eth0 | cut -d ' ' -f 1 gives me eth0 but anything else like -f 2, -f 3 etc I get nothing.

Jerry

There's multiple spaces in the output that cut is hitting - use tr to reduce them.

ifconfig | grep eth0 | tr -s ' ' ' ' | cut -d ' ' -f 5

/sbin/ifconfig | grep eth0 | awk '{ print $5 }'

for the lazy way or "man gawk" to see how to select and print and skip lines of no interest, eliminating the grep.

HTH

On Thu, Feb 28, 2008 at 08:13:17AM -0600, Les Mikesell wrote:

Jerry Geis wrote:

...

I am trying to grab the mac address for eth0 on centos 5.1 with

ifconfig | grep eth0 | cut -d ' ' -f 5 and I dont get anything.

What am I not doing right?

ifconfig | grep eth0 | cut -d ' ' -f 1 gives me eth0 but anything else like -f 2, -f 3 etc I get nothing.

If sed had been invented first, we wouldn't need grep.

ifconfig |sed -n -e 's/eth0.*(..:..:..:..:..:..)/\1/p'

-- Les Mikesell lesmikesell@gmail.com

Specifying eth0 as ifconfig parameter also would be better once there is eth0:0, eth0:1, etc. Otherwise multiple lines would be returned.

Wojtek

On Thu, 28 Feb 2008, Paul Heinlein wrote:

On Thu, 28 Feb 2008, Wojtek Pilorz wrote:

...

On Thu, Feb 28, 2008 at 08:13:17AM -0600, Les Mikesell wrote:

...

Jerry Geis wrote:

...

I am trying to grab the mac address for eth0 on centos 5.1 with

ifconfig | grep eth0 | cut -d ' ' -f 5 and I dont get anything.

What am I not doing right?

ifconfig | grep eth0 | cut -d ' ' -f 1 gives me eth0 but anything else like -f 2, -f 3 etc I get nothing.

If sed had been invented first, we wouldn't need grep.

ifconfig |sed -n -e 's/eth0.*(..:..:..:..:..:..)/\1/p'

Or awk! :-) And you can ditch ifconfig entirely and use /sbin/ip, which defaults to a lower-case version of the MAC rather than the upper-case presentation used by ifconfig:

ip link show eth0 | awk '/ether/ {print $2}'

ip also has a one-line output mechanism:

ip -o link show

which could lead you to:

ip -o link show | awk '/ether/ { print $2 " " $11 }'

On Fri, 29 Feb 2008, John R Pierce wrote:

...

ip also has a one-line output mechanism:

ip -o link show

...

I do wish the mothership would update its standard network configuration scripts to use ip(8) rather than the legacy ifconfig(8). Rather than using the legacy eth0:1 style interface aliases, allow a single /etc/sysconfig/network-scripts/ifcfg-eth0 to contain a list of aliases which get set with

ip addr add ......

ditto optional static routes could be set with

ip route add ...

The great mothership fulfilled your wishes retrospectively if you use route-eth0 to set your routes :) Eg.

1.2.3.4 via 4.3.2.1 8.4.2.0/24 via 7.5.3.1

would be the same as:

route add -host 1.2.3.4 gw 4.3.2.1 route add -net 8.4.2.0 netmask 255.255.255.0 gw 7.5.3.1