refactor/robust(show-busy-java-threads): use printf 💪 instead of echo; use if-else instead of &&-||

NOTE:

- 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/show-busy-java-threads

@@ -53,59 +53,66 @@ readonly ec=$'\033'      # escape char
 readonly eend=$'\033[0m' # escape end
 readonly nl=$'\n'        # new line
 
-colorEcho() {
+colorPrint() {
   local color=$1
   shift
 
   # if stdout is console, turn on color output.
-  [ -t 1 ] && echo "${ec}[1;${color}m$*$eend" || echo "$@"
+  if [ -t 1 ]; then
+    printf "\033[1;${color}m%s\033[0m\n" "$*"
+  else
+    printf '%s\n' "$*"
+  fi
 }
 
-colorPrint() {
+__appendToFile() {
+  [[ -n "$append_file" && -w "$append_file" ]] && printf '%s\n' "$*" >>"$append_file"
+  [[ -n "$store_dir" && -w "$store_dir" ]] && printf '%s\n' "$*" >>"${store_file_prefix}$PROG"
+}
+
+colorOutput() {
   local color=$1
   shift
 
-  colorEcho "$color" "$@"
-  [[ -n "$append_file" && -w "$append_file" ]] && echo "$@" >>"$append_file"
-  [[ -n "$store_dir" && -w "$store_dir" ]] && echo "$@" >>"${store_file_prefix}$PROG"
+  colorPrint "$color" "$*"
+  __appendToFile "$*"
 }
 
 # shellcheck disable=SC2120
-normalPrint() {
-  echo "$@"
-  [[ -n "$append_file" && -w "$append_file" ]] && echo "$@" >>"$append_file"
-  [[ -n "$store_dir" && -w "$store_dir" ]] && echo "$@" >>"${store_file_prefix}$PROG"
+normalOutput() {
+  printf '%s\n' "$*"
+  __appendToFile "$*"
 }
 
-redPrint() {
-  colorPrint 31 "$@"
+redOutput() {
+  colorOutput 31 "$*"
 }
 
-greenPrint() {
-  colorPrint 32 "$@"
+greenOutput() {
+  colorOutput 32 "$*"
 }
 
-yellowPrint() {
-  colorPrint 33 "$@"
+yellowOutput() {
+  colorOutput 33 "$*"
 }
 
-bluePrint() {
-  colorPrint 36 "$@"
+blueOutput() {
+  colorOutput 36 "$*"
 }
 
 die() {
-  redPrint "Error: $*" 1>&2
+  redOutput "Error: $*" 1>&2
   exit 1
 }
 
 logAndRun() {
-  echo "$@"
+  printf '%s\n' "$*"
   echo
   "$@"
 }
 
 logAndCat() {
-  echo "$@"
+  printf '%s\n' "$*"
   echo
   cat
 }
@@ -147,7 +154,7 @@ usage() {
   # shellcheck disable=SC2015
   [ "$exit_code" != 0 ] && local -r out=/dev/stderr || local -r out=/dev/stdout
 
-  (($# > 0)) && colorEcho 31 "$*$nl" >$out
+  (($# > 0)) && colorPrint 31 "$*$nl" >$out
 
   cat >$out <<EOF
 Usage: ${PROG} [OPTION]... [delay [count]]
@@ -202,7 +209,7 @@ EOF
 }
 
 progVersion() {
-  echo "$PROG $PROG_VERSION"
+  printf '%s\n' "$PROG $PROG_VERSION"
   exit
 }
 
@@ -386,9 +393,9 @@ cleanupWhenExit() {
 trap cleanupWhenExit EXIT
 
 headInfo() {
-  colorEcho "0;34;42" ================================================================================
-  echo "$(date "+%Y-%m-%d %H:%M:%S.%N") [$((update_round_num + 1))/$update_count]: $(printCallingCommandLine)"
-  colorEcho "0;34;42" ================================================================================
+  colorPrint "0;34;42" ================================================================================
+  printf '%s\n' "$(date "+%Y-%m-%d %H:%M:%S.%N") [$((update_round_num + 1))/$update_count]: $(printCallingCommandLine)"
+  colorPrint "0;34;42" ================================================================================
   echo
 }
 
@@ -434,13 +441,13 @@ findBusyJavaThreadsByPs() {
   [ -n "$ps_out" ] || __die_when_no_java_process_found
 
   if [ -n "$store_dir" ]; then
-    echo "$ps_out" | logAndCat "${ps_cmd_line[*]} | sort -k3,3nr" >"${store_file_prefix}$((update_round_num + 1))_ps"
+    printf '%s\n' "$ps_out" | logAndCat "${ps_cmd_line[*]} | sort -k3,3nr" >"${store_file_prefix}$((update_round_num + 1))_ps"
   fi
 
   if ((count > 0)); then
-    echo "$ps_out" | head -n "${count}"
+    printf '%s\n' "$ps_out" | head -n "${count}"
   else
-    echo "$ps_out"
+    printf '%s\n' "$ps_out"
   fi
 }
 
@@ -473,13 +480,13 @@ __top_threadId_cpu() {
   local top_out
   top_out=$(HOME="$tmp_store_dir" "${top_cmd_line[@]}")
   if [ -n "$store_dir" ]; then
-    echo "$top_out" | logAndCat "${top_cmd_line[@]}" >"${store_file_prefix}$((update_round_num + 1))_top"
+    printf '%s\n' "$top_out" | logAndCat "${top_cmd_line[@]}" >"${store_file_prefix}$((update_round_num + 1))_top"
   fi
 
   # DO NOT combine var result_threads_top_info declaration and assignment in ONE line!
   local result_threads_top_info
   result_threads_top_info=$(
-    echo "$top_out" | awk '{
+    printf '%s\n' "$top_out" | awk '{
             # from text line to empty line, increase block index
             if (previousLine && !$0) blockIndex++
             # only print 4th text block(blockIndex == 3), aka. process info of second top update
@@ -490,7 +497,7 @@ __top_threadId_cpu() {
   )
   [ -n "$result_threads_top_info" ] || __die_when_no_java_process_found
 
-  echo "$result_threads_top_info" | sort -k2,2nr
+  printf '%s\n' "$result_threads_top_info" | sort -k2,2nr
 }
 
 __complete_pid_user_by_ps() {
@@ -501,21 +508,21 @@ __complete_pid_user_by_ps() {
   local ps_out
   ps_out="$("${ps_cmd_line[@]}")"
   if [ -n "$store_dir" ]; then
-    echo "$ps_out" | logAndCat "${ps_cmd_line[@]}" >"${store_file_prefix}$((update_round_num + 1))_ps"
+    printf '%s\n' "$ps_out" | logAndCat "${ps_cmd_line[@]}" >"${store_file_prefix}$((update_round_num + 1))_ps"
   fi
 
   local idx=0 threadId pcpu output_fields
   while read -r threadId pcpu; do
     ((count <= 0 || idx < count)) || break
 
     # output field: pid, threadId, pcpu, user
-    output_fields="$(echo "$ps_out" |
+    output_fields="$(printf '%s\n' "$ps_out" |
       awk -v "threadId=$threadId" -v "pcpu=$pcpu" '$2==threadId {
                 print $1, threadId, pcpu, $3; exit
             }')"
     if [ -n "$output_fields" ]; then
       ((idx++))
-      echo "$output_fields"
+      printf '%s\n' "$output_fields"
     fi
   done
 }
@@ -543,20 +550,20 @@ printStackOfThreads() {
         logAndRun sudo -u "${user}" "${jstack_cmd_line[@]}" >"${jstackFile}"
       else
         # current user is not root user, so can not run with sudo; print error message and rerun suggestion
-        redPrint "[$idx] Fail to jstack busy(${pcpu}%) thread(${threadId}/${threadId0x}) stack of java process(${pid}) under user(${user})."
-        redPrint "User of java process($user) is not current user($USER), need sudo to rerun:"
-        yellowPrint "    sudo $(printCallingCommandLine)"
-        normalPrint
+        redOutput "[$idx] Fail to jstack busy(${pcpu}%) thread(${threadId}/${threadId0x}) stack of java process(${pid}) under user(${user})."
+        redOutput "User of java process($user) is not current user($USER), need sudo to rerun:"
+        yellowOutput "    sudo $(printCallingCommandLine)"
+        normalOutput
         continue
       fi || {
-        redPrint "[$idx] Fail to jstack busy(${pcpu}%) thread(${threadId}/${threadId0x}) stack of java process(${pid}) under user(${user})."
-        normalPrint
+        redOutput "[$idx] Fail to jstack busy(${pcpu}%) thread(${threadId}/${threadId0x}) stack of java process(${pid}) under user(${user})."
+        normalOutput
         rm "${jstackFile}" &>/dev/null
         continue
       }
     }
 
-    bluePrint "[$idx] Busy(${pcpu}%) thread(${threadId}/${threadId0x}) stack of java process(${pid}) under user(${user}):"
+    blueOutput "[$idx] Busy(${pcpu}%) thread(${threadId}/${threadId0x}) stack of java process(${pid}) under user(${user}):"
 
     if [ -n "$mix_native_frames" ]; then
       local sed_script="/--------------- $threadId ---------------/,/^---------------/ {