bash functions I use time and time again in scripts

functions.sh

#!/bin/bash

# Wrapper around apt/apt-get install to avoid all interactive prompts
function apt_install {
    local DEBIAN_FRONTEND=noninteractive
    local DEBIAN_PRIORITY=critical
    export DEBIAN_FRONTEND DEBIAN_PRIORITY
    sudo /usr/bin/apt-get install --yes --quiet --option Dpkg::Options::=--force-confold --option Dpkg::Options::=--force-confdef "$@"

    return $?
}

# echo, but to STDERR
function echo_error {
    >&2 echo "$@"

    return $?
}

# tee, but sudo'd and no output
function sudo_tee {
    # shellcheck disable=SC2068
    sudo tee $@ >/dev/null

    return $?
}

# Wrapper to retry a command so many times, waiting X+X seconds each time
# e.g. retry 5 5 some_command
# will run some_command at most 5 times, with a backoff starting at 5 seconds,
# then 10, 20, and 40 seconds.
function retry {
  local RETRIES="$1"
  local BACKOFF="$2"
  local COMMAND="$3"
  local EXIT_CODE=

  set +e
  # Run the command, and save the exit code
  ${COMMAND}
  EXIT_CODE=$?
  set -e

  if [[ "${EXIT_CODE}" != 0 && "${RETRIES}" -gt 0 ]]
  then
    sleep "${BACKOFF}"
    retry $(("${RETRIES}" - 1)) $(("${BACKOFF}" + "${BACKOFF}")) "${COMMAND}"
  else
    # Return the exit code from the command
    return "${EXIT_CODE}"
  fi
}