strongDM bash completion of hostnames for "sdm ssh [hostname]"

sdm-completion.bash

#/usr/bin/env bash

# fetch server hostnames from `sdm status` to use as completions for `sdm ssh [hostname]`
# save the sdm status to a local file from a cron job to speed this up a lot:
#   sdm status --filter 'TYPE:ssh*' | tail -n +2 | awk '{print $1}' | sort -u > /var/tmp/sdm-status

# h/t https://iridakos.com/programming/2018/03/01/bash-programmable-completion-tutorial

update_frequency=4h
compwords_file=/var/tmp/sdm-status

_sdm_ssh_completions()
{
   if [ "${#COMP_WORDS[@]}" != "3" ]; then
     return
   fi

  # is this "sdm ssh" ?
  if [ "${3}" != "ssh" ]; then
    return
  fi

  # keep the suggestions in a local variable
  # local suggestions=($(compgen -W "$(sdm status --filter 'TYPE:ssh*' | tail -n +2 | awk '{print $1}')" -- "${COMP_WORDS[2]}"))

  # occasionally save "sdm status" output to a file for much faster completions
  if [ ! -s "$compwords_file" ]; then
    sdm status --filter 'TYPE:ssh*' | tail -n +2 | awk '{print $1}' > $compwords_file
  elif ! test "$( find $compwords_file -ctime -${update_frequency} 2>/dev/null )"; then
    # echo "Updating compwords"
    sdm status --filter 'TYPE:ssh*' | tail -n +2 | awk '{print $1}' > $compwords_file
  fi

  local suggestions=($(compgen -W "$(cat /var/tmp/sdm-status)" -- "${COMP_WORDS[2]}"))

  if [ "${#suggestions[@]}" == "1" ]; then
    # if there's only one match, we remove the command literal
    # to proceed with the automatic completion of the number
    local number=$(echo ${suggestions[0]/%\ */})
    COMPREPLY=("$number")
  else
    # more than one suggestions resolved,
    # respond with the suggestions intact
    for i in "${!suggestions[@]}"; do
      suggestions[$i]="$(printf '%*s' "-$COLUMNS"  "${suggestions[$i]}")"
    done
    COMPREPLY=("${suggestions[@]}")
  fi
}

complete -F _sdm_ssh_completions sdm

use "sdm status" not "sdm admin list"