Quoting and concatenating a fish function argument

Question

I keep destroying and provisioning VMs, so ssh frequently complains that I'm being NASTY. Mmmm...

Anyways, I wrote a fish function to banish the offending key on the line it tells me with sed:

function forgethost
   sed -i.bak {$argv}d ~/.ssh/known_hosts
end

but I'd like to keep the command quoted to protect me against (injecting) myself a little bit. When I wrap it in '', it then doesn't replace $argv. Also, I'd prefer to just grab the first argument [0], but when I add that it also doesn't expand.

Answer 1

Create a ~/.ssh/config entry for the VMs you're continually recreating. Example below. Means you don't have to keep hacking your ~/.ssh/known_hosts file.

Host test-vm-1
    StrictHostKeyChecking no

Answer 2

When I wrap it in '', it then doesn't replace $argv.

What you want is double-quotes, i.e. "$argv". This is the same as in other shells.

Also, I'd prefer to just grab the first argument [0], but when I add that it also doesn't expand.

In fish, the first element of a list has the index 1, so you want $argv[1].

Together that means

function forgethost
   sed -i.bak "$argv[1]"d ~/.ssh/known_hosts
end

Of course you could also add error handling if more than one argument has been given with

if set -q argv[2] # yes, no $
    echo "This only accepts one argument" >&2
    return 1
endt