mjhjmtu

By default ifconfig will show me all available interfaces , but what if I just want to display active ones? Like, en0 only in below.

en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
 ether 14:10:9f:e0:eb:c9 
 inet6 fe80::1610:9fff:fee0:ebc9%en0 prefixlen 64 scopeid 0x4 
 inet X.X.X.X netmask 0xffffff00 broadcast 101.6.69.255
 nd6 options=1<PERFORMNUD>
 media: autoselect
 **status: active**
en3: flags=8963<UP,BROADCAST,SMART,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
 options=60<TSO4,TSO6>
 ether 32:00:14:e7:4f:80 
 media: autoselect <full-duplex>
 **status: inactive**

Notice ifconfig en0 will not satisfy, en0 is not always the active one ;)

I'm running Mac OS X.

To get a complete description of all the active services, try:

ifconfig | pcregrep -M -o '^[^t:]+:([^n]|nt)*status: active'

This simple regex should filter out only active interfaces and all their information. I sugest you put an alias for this in your ~/.profile or ~/.bash_profile file (maybe ifconfiga?)

To just get the interface name (useful for scripts), use:

ifconfig | pcregrep -M -o '^[^t:]+:([^n]|nt)*status: active' | egrep -o -m 1 '^[^t:]+'

You have to install pcregrep for this to work. It's on macports in the pcre package. Alternatively, this should work with GNU grep using grep -Pzo instead of pcregrep -M -o but with the rest the same, but I haven't tested this.

If you only want to print the “entry” if it contains status: active, then you could use something like this awk program as a filter to the ifconfig output:

#!/usr/bin/awk -f
BEGIN print_it = 0 
/status: active/ print_it = 1 
/^($|[^t])/ if(print_it) print buffer; buffer = $0; print_it = 0 
/^t/ buffer = buffer "n" $0 
END if(print_it) print buffer 

When each “entry” starts (a line is empty or does not start with a Tab), start saving the entry in a buffer. Append to this buffer any subsequent lines that start with a Tab. Watch for the magic string status: active; if a line like that was seen, print out the buffer (the previous “entry”) when a new “entry” starts (or the input ends).

Save the above program text in a file and use it like this:

ifconfig -a | awk -f /path/to/file

Or, if you chmod +x the file, then you can simplify it a bit:

ifconfig -a | /path/to/file

Reading your comments and question, it seems you actually want to just get the interfaces that have an IP address assigned to them.

You can do this quickly with ifconfig and grep.

Running the command:

ifconfig | grep 'Link|inet'

Should produce something similar to:

eth0 Link encap:Ethernet HWaddr 00:11:22:33:44:55
eth1 Link encap:Ethernet HWaddr 00:11:22:33:44:66 
 inet addr:192.168.0.8 Bcast:192.168.0.255 Mask:255.255.255.0
lo Link encap:Local Loopback 
 inet addr:127.0.0.1 Mask:255.0.0.0

This would show each line with a interface name and and IP if they had one.

Some more specific REGEX magic might get you exactly what you need.

Following will print out only those interfaces that are configured to have an IP

ifconfig | grep "inet.*broadcast"

If you are not adverse to some bash scripting, you can do this:

for i in $(ifconfig -lu); do if ifconfig $i | grep -q "status: active" ; then echo $i; fi; done

That's will list out the active network interfaces. Tested on Mac OS X 10.13.

The nice thing is that you don't need to install anything. Just run the above in a Terminal.

$ ifconfig | grep "inet addr:" | grep -v 127.0.0.1 | sed -e 's/Bcast//' | cut -d: -f2

How it works:

• ifconfig


• Grep for lines containing "inet addr"
  
  
  • These lines contains the IPs.
  
  


• Grep for lines that do not contain "127.0.0.1"
  
  
  • We usually do not care about localhost.
  
  
  • -v is inverted grep
  
  


• From remaining lines, remove the "Bcast"


• Cut field 2 using ":" as a delimiter
  
  
  • Prints the answer.
  
  

ifconfig en0 | grep status

This will show the status of the ethernet connection en0