Initial file structrue and rdlink with essential content

.editorconfig

@@ -0,0 +1,6 @@
+root = true
+
+[*.sh]
+charset = utf-8
+indent_style = space
+indent_size = 2

rdlink.sh

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+#!/usr/bin/env bash
+
+## rdlink [-d|--debug] <PATH>
+##
+## License: GNU GPL V3 or later
+##  Author: Martin Winkler
+
+# Exit on error. Append "|| true" if you expect an error.
+set -o errexit
+# Exit on error inside any functions or subshells.
+set -o errtrace
+# Do not allow use of undefined vars. Use ${VAR:-} to use an undefined VAR
+set -o nounset
+# Catch the error in case mysqldump fails (but gzip succeeds) in `mysqldump |gzip`
+set -o pipefail
+
+LOG_LEVEL="${LOG_LEVEL:-1}" # 7 = debug -> 0 = emergency
+
+rl::rdlink() {
+  local normalized=
+  info "Processing... $@"
+  normalized="$(rl::normalize "${1:-}")"
+  rl::quicklink "${normalized}"
+}
+
+rl::canon() {
+  info "Canonicalize path... $@"
+}
+
+rl::quicklink() {
+  info "Quick rdlink... ${1:-}"
+  readlink "${1:-}" || printf "${1:-}\n"
+}
+
+rl::normalize() {
+  info "Normalizing... ${1:-}"
+  printf "${1:-}\n"
+}
+
+rl::main() {
+  local file=
+  local arg=
+
+  for arg in "$@"; do
+    case "$arg" in
+      --)
+        shift
+        break ;;
+      -d|--debug)
+        shift
+        LOG_LEVEL=7 ;;
+      -dd)
+        shift
+        set -o xtrace ;;
+      -*)
+        shift ;;
+    esac
+  done
+
+  info "BASH rdlink"
+
+  for file in "$@"; do
+    rl::rdlink "$file"
+  done
+}
+
+function rl::log () {
+  local log_level="${1:-${LOG_LEVEL}}"
+  shift
+
+  # all remaining arguments are to be printed
+  local log_line=""
+
+  while IFS=$'\n' read -r log_line; do
+    printf "%s [%9s] %s\n" "$(date -u +"%Y-%m-%d %H:%M:%S UTC")" "${log_level}" "${log_line}" 1>&2
+  done <<< "${@:-}"
+}
+emergency () {                                  rl::log emergency "${@}"; exit 1; }
+alarm()      { [[ "${LOG_LEVEL:-0}" -ge 1 ]] && rl::log alert "${@}"; true; }
+critical ()  { [[ "${LOG_LEVEL:-0}" -ge 2 ]] && rl::log critical "${@}"; true; }
+error ()     { [[ "${LOG_LEVEL:-0}" -ge 3 ]] && rl::log error "${@}"; true; }
+warning ()   { [[ "${LOG_LEVEL:-0}" -ge 4 ]] && rl::log warning "${@}"; true; }
+notice ()    { [[ "${LOG_LEVEL:-0}" -ge 5 ]] && rl::log notice "${@}"; true; }
+info ()      { [[ "${LOG_LEVEL:-0}" -ge 6 ]] && rl::log info "${@}"; true; }
+debug ()     { [[ "${LOG_LEVEL:-0}" -ge 7 ]] && rl::log debug "${@}"; true; }
+msg ()       {                                  echo "$@"; true; }
+
+
+# Provide as function to be called when sourced
+rdlink() {
+  rl::main "$@"
+}
+
+### Check if script is _sourced
+### https://stackoverflow.com/a/28776166
+_sourced=0
+if [ -n "${ZSH_EVAL_CONTEXT:-}" ]; then
+  case ${ZSH_EVAL_CONTEXT:-} in *:file) _sourced=1;; esac
+elif [ -n "${KSH_VERSION:-}" ]; then
+  [ "$(cd $(dirname -- $0) && pwd -P)/$(basename -- $0)" != "$(cd $(dirname -- ${.sh.file}) && pwd -P)/$(basename -- ${.sh.file})" ] && _sourced=1
+elif [ -n "${BASH_VERSION:-}" ]; then
+  (return 0 2>/dev/null) && _sourced=1
+else # All other shells: examine $0 for known shell binary filenames
+  # Detects `sh` and `dash`; add additional shell filenames as needed.
+  case ${0##*/} in sh|dash) _sourced=1;; esac
+fi
+###
+
+if (( ! _sourced )); then
+  rl::main "$@"
+fi
+

test/test_rdlink.sh

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+#!/bin/bash
+
+tool_a="/opt/rdlink/rdlink.sh"
+tool_b="$(command -v readlink) -f"
+
+test_links=( "Valid links"
+  "/dev/stdin"
+  "$HOME/tmp/a"*
+  "$HOME/tmp/a 3"
+  "/bin/adb"
+)
+
+test_all=( "Test everything starting from /"
+  /**/*
+)
+
+test_args=( "Tests from command line"
+  "$@"
+)
+
+totest=(
+  test_links
+)
+
+[[ "$@" ]] && totest=(test_args)
+
+rl::test() {
+  local i=0
+  local ra=
+  local rb=
+  local path=
+  local testarray=
+  local testend=0
+
+  for testarray in "${totest[@]}"; do
+    i=0
+    testarray="$testarray"[@]
+    for path in "${!testarray}"; do
+      
+      if (( ! i )); then
+        # Print title in array element 0
+        printf "         ### %s ###\n" "$path"
+      else
+        # Execute tests
+        printf -- "%-3d --- %-30s ---" $i "$path"
+        ra="$(${tool_a} "$path")"
+        rb="$(${tool_b} "$path")"
+        if [[ "$ra" = "$rb" ]]; then
+          # Test successful
+          printf " OK\n"
+        else
+          # Test failed
+          printf " FAIL\n"
+          printf "\n Result:\n%s\n%s\n" "$ra" "$rb"
+          printf "\n Subject:\n"
+          ls -al "$path"
+
+          # Print debug output of tool_a
+          printf "\n Debug:\n"
+          ( "${tool_a}" -d "${path}" )
+
+          testend=1 && break
+        fi
+      fi
+
+      ((i++))
+    done
+    (( testend )) && break
+  done
+}
+
+time rl::test