How to make zsh autocomplete failover to compdef _files

I needed to get the fingerprint of a ssh key using:

$ ssh-keygen -lf ~/.ssh/id_rsa_user.pub

after typing:ssh-keygen -lf ~/.ss TAB It was not giving any options.

I had to do:

$ compdef _files ssh-keygen

After that I was available to autocomplete using the files path, but the command autocomplete stop working, so if if I type ssh-keygen - Tab I don't see any more this output:

$ ssh-keygen -
 -- option --
-B  -- show the bubblebabble digest of key
-C  -- provide new comment
-D  -- download key stored in smartcard reader
-N  -- provide new passphrase
-P  -- provide old passphrase
-U  -- upload key to smartcard reader
-b  -- specify number of bits in key
-c  -- change comment in private and public key files
-e  -- export key to SECSH file format
-f  -- key file
-i  -- import key to OpenSSH format
-l  -- show fingerprint of key file
-p  -- change passphrase of private key file
-q  -- silence ssh-keygen
-t  -- specify the type of the key to create
-y  -- get public key from private key

So wondering if there is a way of having both options enabled so that I can do something like:

ssh-keyg TAB that will give me:

$ ssh-keygen

Then I can do

$ ssh-keygen - TAB

That would print the option menu and been available to do:

$ ssh-keygen -lf ~/.ss TAB

And have list of options what could work so at the end I would get something like:

$ ssh-keygen -lf ~/.ssh/id_rsa_user.pub

For now I just add to my ~/.zshrc this:

compdef _files ssh-keygen
compdef _files adb
compdef _files mysql
...

But I have to do that for avery command I want to use the _files completion, therefore I would like to know if there is a way to always use _files or failover to it.

Any ideas?

Could it be possible to make it behave like csh in where pressing Ctrl+d shows files options?

Update:

I notice that if I the last argument is an -f the autocomplete works:

ssh-keygen -l -f ~/.sshTAB

But for custom scripts, commands what function, widget alias could help do force the _files completion.?

Solution

The solution was to update to zsh this is how I did it:

# check the zsh info
brew info zsh

# install zsh
brew install zsh

# add shell path
sudo vim /etc/shells

# add the following line into the very end of the file(/etc/shells)
/usr/local/bin/zsh

# change default shell
chsh -s /usr/local/bin/zsh

I had issues completing git-flow this was fixed by reinstalling with --without-completions:

$ brew install git --without-completions