Bash Script - 自製 ipconfig 命令

1.撰寫 ipconfig 程式
#!/bin/bash

iname="eth0 eth1 eth2 eth3"

# interfaces
for i in $iname
do
  x=$(ifconfig -a | grep -A1 $i)
  if [ ! -z "$x" ]; then
    ifn="${x%% *}"
    echo "$ifn"

    t=${x#*HWaddr }
    echo "   MAC : ${t%% *}"

    t=${x#*inet addr:}
    [ "$t" != "$x" ] && echo "   IP  : ${t%% *}"

    r=$(route -n | grep '^0.0.0.0' | grep "$ifn")
    if [ ! -z "$r" ]; then
      t=${r#0.0.0.0}
      t=$(echo $t)                   # 刪除開頭多個空白字元
      echo "   GW  : ${t%% *}"
    fi
    echo ""
  fi
done

# nameserver
dn=$(cat /etc/resolv.conf | grep 'nameserver')
echo "DNS"
echo "  ${dn//nameserver/}"
echo ""
exit 0

2. 設定執行權限

$ chmod +x ipconfig

3. 執行程式

$ ./ipconfig

eth0
   MAC : 00:0c:29:35:5a:90
   IP  : 192.168.111.146
   GW  : 192.168.111.2

eth1
   MAC : 00:0c:29:35:5a:9a

DNS
   192.168.111.2