ZSH custom completion from command output

Question

I am creating a custom completion for my command ipadd which will automatically complete all the network devices for OS X. It has a parameter --device which allows you to specify the network devices on the system.

The command to list the network devices in OS X is

networksetup -listallnetworkservices

The output for it is;

An asterisk (*) denotes that a network service is disabled.
Ethernet
Wi-Fi

However the first line of the command isn't the network interface and I have modified that command about so that it only shows Ethernet and Wi-Fi

networksetup -listallnetworkservices | sed -n '2,$p'

The output for this is;

Ethernet
Wi-Fi

My question is how can I store that command and use it for auto completion for my ipadd command. I know that you can use the _files but that is for completing files within the system.

Thanks in advance :)

Answer 1

1. Create a file named _ipadd and put the following in it:

   #compdef ipadd
   
   # The line above declares this function as providing completions to 
   # `ipadd`. In addition, it's important that the file name starts with 
   # an `_`, otherwise `compinit` won't autoload it.
   
   local output=$(networksetup -listallnetworkservices)
   
   # Split the output on newlines.
   local -a services=( ${(f)output} )
   
   # Offer the second to the last line as completions.
   _arguments "*:network service:( ${services[2,-1]} )"
   

2. Make sure the folder that contains this file is in your $fpath. So, if we suppose it's located in ~/func, then you can do something like this in your .zshrc file:

   fpath+=( ~/func )
   

3. Make sure you call compinit in your ~/.zshrc file after adding the dir to your $fpath. Otherwise, it will not be used for completions.

   autoload -Uz compinit && compinit