template script

template.sh

@@ -0,0 +1,150 @@
+#!/usr/bin/env bash
+
+# Example Bash Shell Script
+# from https://betterdev.blog/minimal-safe-bash-script-template/
+
+set -Eeuo pipefail
+
+cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1
+
+# declare globals as readonly
+readonly SCRIPT_NAME
+SCRIPT_NAME="$(basename "$0")"
+
+trap cleanup SIGINT SIGTERM ERR EXIT
+
+usage() {
+  cat <<EOF
+Usage: $(basename "$0") [-h] [-v] [-f] -p param_value arg1 [arg2...]
+
+Script description here.
+
+Available options:
+
+-h, --help      Print this help and exit
+-v, --verbose   Print script debug info
+-f, --flag      Some flag description
+-p, --param     Some param description
+EOF
+  exit
+}
+
+cleanup() {
+  trap - SIGINT SIGTERM ERR EXIT
+  # script cleanup here
+}
+
+setup_colors() {
+  if [[ -t 2 ]] && [[ -z ${NO_COLOR-} ]] && [[ ${TERM-} != "dumb" ]]; then
+    NOCOLOR='\033[0m' RED='\033[0;31m' GREEN='\033[0;32m' ORANGE='\033[0;33m' BLUE='\033[0;34m' PURPLE='\033[0;35m' CYAN='\033[0;36m' YELLOW='\033[1;33m'
+  else
+    # shellcheck disable=SC2034
+    NOCOLOR='' RED='' GREEN='' ORANGE='' BLUE='' PURPLE='' CYAN='' YELLOW=''
+  fi
+}
+
+# you only need one of the following two functions
+# simple function to redirect output to stderr (good)
+msg() {
+  echo >&2 -e "${1-}"
+}
+
+# more structured logging (better)
+log() {
+  local -r level="$1"
+  local -r message="$2"
+  local -r timestamp=$(date +"%Y-%m-%d %H:%M:%S")
+
+  # colorize your log output here, if desired
+  echo >&2 -e "${timestamp} [${level}] [$SCRIPT_NAME] ${message}"
+}
+
+die() {
+  local msg=$1
+  local code=${2-1} # default exit status 1
+  log "FATAL" "$msg"
+  exit "$code"
+}
+
+assert_not_empty() {
+  local -r arg_name="$1"
+  local -r arg_value="$2"
+
+  if [[ -z $arg_value ]]; then
+    log "ERROR" "The value for '$arg_name' cannot be empty"
+    exit 1
+  fi
+}
+
+assert_is_installed() {
+  local -r name="$1"
+
+  if [[ ! $(command -v "$name") ]]; then
+    log "ERROR" "The binary '$name' is required by this script but is not installed or in the system's PATH."
+    exit 1
+  fi
+}
+
+parse_params() {
+  while :; do
+    case "${1-}" in
+    -h | --help)
+      usage
+      ;;
+    -v | --verbose)
+      set -x
+      ;;
+    --no-color)
+      NO_COLOR=1
+      ;;
+    -f | --flag) # example flag
+      # FLAG=1
+      ;;
+    -p | --param) # example named parameter
+      assert_not_empty "--param", "${2-}"
+      PARAM="${2-}"
+      shift
+      ;;
+    -?*)
+      die "Unknown option: $1"
+      ;;
+    *)
+      break
+      ;;
+    esac
+    shift
+  done
+
+  # check required params and arguments
+  assert_is_installed "bash"
+
+  return 0
+}
+
+# default values of variables set from parse_params
+# to avoid having these variables here, you will need to define the work of
+# the script as another function that takes arguments and call it with local
+# variables declared in parse_params:
+#
+# run() {
+#  local -r flag=$1
+# }
+#
+# parse_params() {
+#   local flag=0
+#    ...
+#   run $flag
+# }
+FLAG=0
+PARAM=''
+readonly ARGS=("$@")
+
+parse_params "$@"
+setup_colors
+
+# script logic here
+
+log "INFO" "${RED}Read parameters:${NOCOLOR}"
+log "INFO" "- flag: ${FLAG}"
+log "INFO" "- param: ${PARAM}"
+log "INFO" "- arguments: ${ARGS[*]-}"