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Accepted
Artur Meinild
Asked: 2022-03-27 15:10:24 +0800 CST

How do you add Bash autocompletion to a snap that doesn't have it (example: canonical-livepatch)

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The canonical-livepatch snap does not feature autocompletion for its subcommands. As per the help page, the valid subcommands are:

$ canonical-livepatch help
...
COMMANDS:
   config - configure livepatching on the machine
   disable - disable livepatching on the machine
   enable - enable livepatching on the machine
   help - display help
   kernel-upgrade-required - indicate whether a kernel upgrade is required
   refresh - immediately download and apply any available livepatch
   status - show kernel's livepatch status

Is there an easy way to add autocompletion for the subcommands in the canonical-livepatch snap that works in Bash, without having to modify the snap itself?

A little detail is that the autocompletion should also work for the snap alias livepatch I have for the command.

$ snap aliases
Command              Alias      Notes
canonical-livepatch  livepatch  manual
lxd.lxc              lxc        -
bash

1 Answers

  1. Best Answer

    This can be done by creating the following autocompletion script (I've called it livepatch-completion):

    # canonical-livepatch completion script

_livepatch_completion()
{
  # Only autocomplete for first subcommand
  if [ "${#COMP_WORDS[@]}" != "2" ]; then
    return
  fi

  # Define the list of words that will autocomplete and display on double-tab
  COMPREPLY=($(compgen -W "config disable enable help kernel-upgrade-required refresh status" "${COMP_WORDS[1]}"))
}

# Initialize the completion function for both the original command and the alias livepatch    
complete -F _livepatch_completion canonical-livepatch livepatch

    Place the script anywhere you like (for instance ~/.bash_completion).

    Source the autocompletion script by adding this line to your ~/.bashrc (or any other file that is sourced when you start the terminal):

    source ~/.bash_completion/livepatch-completion

    This may not be the most advanced solution, but it works for simply autocompleting the subcommands for any other command, including snaps and aliases.

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