refactor/robust(echo-args): use printf 💪 instead of echo; align…

… the index number

bin/echo-args

@@ -6,20 +6,37 @@
 # @author Jerry Lee (oldratlee at gmail dot com)
 set -eEuo pipefail
 
-readonly ec=$'\033'      # escape char
-readonly eend=$'\033[0m' # escape end
+digitCount() {
+  # argument 1(num) is always a non-negative integer in this script usage,
+  # so NO argument validation logic.
+  local num="$1" count=0
+  while ((num != 0)); do
+    ((++count))
+    ((num = num / 10))
+  done
+  echo "$count"
+}
+
+digit_count=$(digitCount $#)
+readonly arg_count=$# digit_count
+
+readonly red='\033[1;31m'
+readonly blue='\033[1;36m'
+readonly normal='\033[0m'
 
-echoArg() {
-  local index="$1" count="$2" value="$3"
+printArg() {
+  local idx="$1" value="$2"
 
   # if stdout is console, turn on color output.
-  [ -t 1 ] &&
-    echo "${index}/${count}: ${ec}[1;31m[$eend${ec}[1;36;40m$value$eend${ec}[1;31m]$eend" ||
-    echo "${index}/${count}: [${value}]"
+  if [ -t 1 ]; then
+    printf "%${digit_count}s/%s: ${red}[${blue}%s${red}]${normal}\n" "$idx" "$arg_count" "$value"
+  else
+    printf "%${digit_count}s/%s: [%s]\n" "$idx" "$arg_count" "$value"
+  fi
 }
 
-echoArg 0 $# "$0"
+printArg 0 "$0"
 idx=1
 for a; do
-  echoArg $((idx++)) $# "$a"
+  printArg $((idx++)) "$a"
 done