Parsing Data from Ifconfig with Awk or Sed

Parsing data from ifconfig with awk or sed?

use grep:

ifconfig | grep -oP '(?<=RX bytes:)[0-9]*'

use awk:

ifconfig | awk -F: '/RX bytes/{print $2+0}'

Parse ifconfig to get only my IP address using Bash

Well, after hours of struggling I finally got it right:

ifconfig en1 | awk '{ print $2}' | grep -E -o "([0-9]{1,3}[\.]){3}[0-9]{1,3}"

That last part I had missing is just grep a pattern of IP addresses from my list.

Parse interfaces from ifconfig

I'll add this one to the pile. Add the quotes in the first sed, then just join the lines with paste.

ifconfig -a | sed -n 's/^\([^ ]\+\).*/"\1"/p' | paste -sd ","

This is better than tr since there's no trailing comma.

Better yet, since ifconfig -a output can't really be counted on to stay consistent, check /sys/class/net

ls /sys/class/net | sed -e 's/^\(.*\)$/"\1"/' | paste -sd ","

display only network interface and ip address using ifconfig and awk

You can use ip route show instead to get the information you want. Filter with this command for example:

ip r show|grep " src "|cut -d " " -f 3,12

outputs something like:

eth0 192.168.1.114

awk to get IP info

Here is a working version based on Kents verson:

ifconfig -a|awk -v RS="" '{for(i=1;i<=NF;i++){
    if($i=="HWaddr") mac=$(i+1)
        else if($i~/addr:[0-9]/) {split($i,a,":");ip=a[2]}
        else if($i~/Mask/) {split($i,a,":");mask=a[2]}}
    if(ip!="127.0.0.1")print $1,mac,ip,bcast,mask}'
eth0 00:18:71:6a:f0:45 192.168.1.30 255.255.255.0

I have skipped the Broad Cast address, since its always the last IP in the segment and normally not needed.

How to extract TX packets from ifconfig

Assuming your kernel is Linux, you're best off asking the kernel to give you the number you want itself:

adapter=eth0
tx_packets=$(</sys/class/net/"$adapter"/tx_packets) || {
  echo "Could not find $adapter" >&2; exit 1
}
echo "Adapter $adapter sent $tx_packets packets"

That way you aren't reliable on a tool that's likely to go away in the future. (ifconfig on Linux has been unmaintained for over a decade now in favor of the iproute2 suite). Moreover, sysfs is where ifconfig is getting the numbers from itself -- so you're cutting out quite a range of middlemen by going there directly.

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As for your attempt at a script, see BashFAQ #50 for a full, detailed description of why it failed and how to reuse code without putting that code in strings. Personally, if I were going to parse ifconfig's output in that way, I might write:

#!/bin/bash
#      ^^^^- pipefail not guaranteed to work with /bin/sh, so use bash here!

set -o pipefail # ensure that pipeline fails if ifconfig does

adapter="eth0"
tx_packets=$(ifconfig "$adapter" | awk '/TX packets/ {print $2}' | cut -d ":" -f2) || exit

echo "Adapter $adapter sent $tx_packets packets"

However, I wouldn't advise parsing ifconfig's output at all.

Note that this output format is not standardized across operating systems, so you can't rely on the popularity of that name (for OS-specific interface configuration tools) to imply that output format will comply with any particular standard.

How to use pipe to parse output of a command

You can achieve this using awk as shown on this site. I've posted an excerpt here which produces your desired result:

ifconfig | awk '/dr:/{gsub(/.*:/,"",$2);print$2}'

Use awk output as variable for string comparison

This generally means that you've got nonprintable characters -- like syntax highlighting, or DOS newlines -- in your variable.

One easy way this can happen is if you've got your grep instance set to always insert color codes, as with --color=always rather than the default (safer) --color=auto.

To track this down, compare the output of the following commands:

printf '%s' "$en1_status" | xxd
printf '%s' inactive | xxd

You can also moot grep's configuration by letting awk do the searching:

en1_status=$(ifconfig en1 | awk '/status: / { print $2 }')

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