POSIX sh boilerplate

template.sh

#!/bin/sh

# # The MIT License (MIT)
#
# Copyright © 2019 **Tub Technology** _<licence@tub.technology>_
#
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation
# files (the “Software”), to deal in the Software without
# restriction, including without limitation the rights to use,
# copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following
# conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.

set -eu

IFS="
	 "

fprint() (
  FD="${1}"
  FMT="${2}"
  shift 2

  if [ -t "${FD}" ]; then
    readonly RED="\\\\033[31m"
    readonly GREEN="\\\\033[32m"
    readonly YELLOW="\\\\033[33m"
    readonly BLUE="\\\\033[34m"
    readonly CYAN="\\\\033[35m"
    readonly MAGENTA="\\\\033[36m"
    readonly RESET="\\\\033[0m"
  else
    readonly RED=""
    readonly GREEN=""
    readonly YELLOW=""
    readonly BLUE=""
    readonly CYAN=""
    readonly MAGENTA=""
    readonly RESET=""
  fi

  readonly CLR="$(echo "${FMT}" | sed "
    s|<r>|${RED}|g;
    s|<y>|${YELLOW}|g;
    s|<g>|${GREEN}|g;
    s|<b>|${BLUE}|g;
    s|<c>|${CYAN}|g;
    s|<m>|${MAGENTA}|g;
    s|<>|${RESET}|g
  ")"

  # shellcheck disable=SC2059
  printf "${CLR}" "$@" 1>&"${FD}"
)

stdout() (
  FMT="${1}"
  shift 1
  fprint 1 "${FMT}\n" "$@"
)

stderr() (
  FMT="${1}"
  shift 1
  fprint 2 "${FMT}\n" "$@"
)

trace() (
  if [ "${VERBOSITY:-1}" -ge 4 ]; then
    stdout "$@"
  fi
)

debug() (
  if [ "${VERBOSITY:-1}" -ge 3 ]; then
    stdout "$@"
  fi
)

info() (
  if [ "${VERBOSITY:-1}" -ge 2 ]; then
    stdout "$@"
  fi
)

warn() (
  if [ "${VERBOSITY:-1}" -ge 1 ]; then
    stderr "$@"
  fi
)

note() (
  FMT="${1}"
  shift 1
  stderr "<y> Note:<> ${FMT}" "$@"
)

error() (
  FMT="${1}"
  shift 1
  stderr "<r>Error:<> ${FMT}" "$@"
)

available() (
  MISSING=""
  for EXECUTABLE in "$@"; do
    if ! command -v "${EXECUTABLE}" >/dev/null 2>&1; then
      MISSING="${MISSING} ${EXECUTABLE}"
    fi
  done
  if test -n "${MISSING}"; then
    error "Missing dependencies:<y>${MISSING}<>"
    note "Use your package manager to install"
    exit 1
  fi
)

LOCATION="${LOCATION:-tool/dependencies}"
VERBOSITY="${VERBOSITY:-2}"

usage() (
  CODE="${1:-0}"
  MSG="${2:-}"
  shift 2 2>/dev/null || true
  if [ -n "${MSG}" ]; then
    "$([ "${CODE}" -gt 0 ] && echo error || echo stdout)" "${MSG}" "$@"
  fi
  PRINT="$([ "${CODE}" = 0 ] && echo stdout || echo stderr)"
  "${PRINT}" "Usage: <b>$0<> [<c>OPTIONS<>]… [<m>LOCATION<>]"
  "${PRINT}" ""
  "${PRINT}" "Options:"
  "${PRINT}" "  <c>-q<>             quiet output, can use multiple times"
  "${PRINT}" "  <c>-v<>             verbose output, can use multiple times"
  "${PRINT}" ""
  "${PRINT}" "Positional:"
  "${PRINT}" "  <m>LOCATION<>       location to install dependencies (<b>${LOCATION}<>)"
  "${PRINT}" ""
  "${PRINT}" "Environment:"
  "${PRINT}" "  <g>LOCATION<>       location to install dependencies"
  "${PRINT}" "  <g>VERBOSITY<>      the output level (<b>${VERBOSITY}<>)"
  "${PRINT}" ""
  "${PRINT}" "Examples:"
  "${PRINT}" "  - Install dependencies in default location"
  "${PRINT}" "    <b>$0<>"
  "${PRINT}" "  - Install dependencies in specific location"
  "${PRINT}" "    <b>$0<> <c>my/custom/install/path<>"
  [ -n "${CODE:-}" ] && exit "${CODE}"
)

readonly DEPENDENCIES="bash curl git mkdir rm unzip which xz"

# shellcheck disable=SC2086
available ${DEPENDENCIES}

while getopts "hqv" OPT; do
  case "${OPT}" in
    q) VERBOSITY=$((VERBOSITY - 1)) ;;
    v) VERBOSITY=$((VERBOSITY + 1)) ;;
    h) usage 0 ;;
    *) usage 1 "Invalid argument: <y>${OPT}<>" ;;
  esac
done

if [ $# -gt 1 ]; then
  usage 1 "Invalid number of positional arguments: <y>$#<>"
elif [ $# -eq 1 ]; then
  LOCATION="$*"
fi