refactor/robust(xpl/xpf): improve robustness 💪 ; check failure and reflect as exit code; improve portability(portableRelPath/portableReadLink)

NOTE:

- use `printf` 💪 instead of `echo`; use `if-else` instead of `&&-||`
  - the `echo` option(e.g. -e -n) may effect correctness, `printf` is more robust 💪
- about `&&-||` see shell check:
  https://www.shellcheck.net/wiki/SC2015

Author: oldratlee

bin/xpf

@@ -1,7 +1,7 @@
 #!/bin/bash
 # @Function
 # Open file in file explorer, file is selected.
-# same as xpl --selected [file [file ...] ]
+# same as xpl --selected [file]...
 #
 # @Usage
 #   $ ./xpf file
@@ -10,6 +10,10 @@
 # @author Jerry Lee (oldratlee at gmail dot com)
 set -eEuo pipefail
 
+################################################################################
+# util functions
+################################################################################
+
 # How can I get the behavior of GNU's readlink -f on a Mac?
 # https://stackoverflow.com/questions/1055671
 portableReadLink() {
@@ -21,10 +25,16 @@ portableReadLink() {
     readlink -f "$file"
     ;;
   Darwin*)
+    local py_args=(-c 'import os, sys; print(os.path.realpath(sys.argv[1]))' "$file")
     if command -v greadlink >/dev/null; then
       greadlink -f "$file"
+    elif command -v python3 >/dev/null; then
+      python3 "${py_args[@]}"
+    elif command -v python >/dev/null; then
+      python "${py_args[@]}"
     else
-      python -c 'import os, sys; print(os.path.realpath(sys.argv[1]))' "$file"
+      echo "fail to find command(greadlink/python3/python) for readlink!" >&2
+      exit 1
     fi
     ;;
   *)
@@ -34,5 +44,13 @@ portableReadLink() {
   esac
 }
 
-BASE="$(dirname "$(portableReadLink "${BASH_SOURCE[0]}")")"
-source "$BASE/xpl" "$@"
+################################################################################
+# biz logic
+################################################################################
+
+# DO NOT inline THIS_SCRIPT into BASE_DIR, because sub-shell:
+#   BASE_DIR="$(dirname "$(portableReadLink "${BASH_SOURCE[0]}")")"
+THIS_SCRIPT="$(portableReadLink "${BASH_SOURCE[0]}")"
+BASE_DIR="$(dirname "$THIS_SCRIPT")"
+
+source "$BASE_DIR/xpl" "$@"

bin/xpl

@@ -30,15 +30,17 @@ PROG="$(basename "$0")"
 readonly PROG
 readonly PROG_VERSION='2.5.0-dev'
 
-readonly nl=$'\n' # new line
+################################################################################
+# util functions
+################################################################################
 
 usage() {
   local -r exit_code="${1:-0}"
   (($# > 0)) && shift
   # shellcheck disable=SC2015
   [ "$exit_code" != 0 ] && local -r out=/dev/stderr || local -r out=/dev/stdout
 
-  (($# > 0)) && echo "$*$nl" >$out
+  (($# > 0)) && printf '%s\n\n' "$*" >$out
 
   cat <<EOF
 Usage: ${PROG} [OPTION] [FILE]...
@@ -56,13 +58,10 @@ EOF
 }
 
 progVersion() {
-  echo "$PROG $PROG_VERSION"
+  printf '%s\n' "$PROG $PROG_VERSION"
   exit
 }
 
-# if program name is xpf, set option selected!
-[ "xpf" == "${PROG}" ] && selected=true
-
 ################################################################################
 # parse options
 ################################################################################
@@ -96,10 +95,13 @@ while [ $# -gt 0 ]; do
   esac
 done
 
+# if program name is xpf, set option selected!
+[ "xpf" == "${PROG}" ] && selected=true
+
 readonly args selected
 
 ################################################################################
-# biz options
+# biz logic
 ################################################################################
 
 # open one file
@@ -109,33 +111,49 @@ openOneFile() {
   case "$(uname)" in
   Darwin*)
     [ -f "${file}" ] && slt=true
-    open ${slt:+-R} "$file"
+    if $slt; then
+      open -R "$file"
+    else
+      open "$file"
+    fi
     ;;
   CYGWIN*)
     [ -f "${file}" ] && slt=true
-    explorer ${slt:+/select,} "$(cygpath -w "${file}")"
+    if $slt; then
+      explorer /select, "$(cygpath -w "${file}")"
+    else
+      explorer "$(cygpath -w "${file}")"
+    fi
     ;;
   *)
     if [ -d "${file}" ]; then
       nautilus "$(dirname "${file}")"
     else
-      if [ -z "${slt}" ]; then
-        nautilus "$(dirname "${file}")"
-      else
+      if $slt; then
         nautilus "${file}"
+      else
+        nautilus "$(dirname "${file}")"
       fi
     fi
     ;;
   esac
+
+  local selected_msg
+  $slt && selected_msg='with selection'
+  printf 'open %14s: %s\n' "$selected_msg" "$file"
 }
 
 [ "${#args[@]}" == 0 ] && files=(.) || files=("${args[@]}")
+has_error=false
+
 for file in "${files[@]}"; do
   [ ! -e "$file" ] && {
-    echo "$file not existed!"
+    printf '%s\n' "$file not existed!"
     continue
   }
 
   openOneFile "$file"
-  echo "$file opened${selected:+ with selection}!"
 done
+
+# set exit status
+! $has_error