diff --git a/bin/ap b/bin/ap
index 1c598985..355163dc 100755
--- a/bin/ap
+++ b/bin/ap
@@ -73,14 +73,13 @@ portableReadLink() {
 usage() {
   local -r exit_code="${1:-0}"
   (($# > 0)) && shift
-  # shellcheck disable=SC2015
-  [ "$exit_code" != 0 ] && local -r out=/dev/stderr || local -r out=/dev/stdout
+  local -r out=$(((exit_code != 0) + 1))
 
   # NOTE: $'foo' is the escape sequence syntax of bash
   local nl=$'\n' # new line
-  (($# > 0)) && redPrint "$*$nl" >"$out"
+  (($# > 0)) && redPrint "$*$nl" >&"$out"
 
-  cat >"$out" <<EOF
+  cat >&"$out" <<EOF
 Usage: ${PROG} [OPTION]... [FILE]...
 convert to Absolute Path.
 
diff --git a/bin/c b/bin/c
index 7faf5487..aaaf4d89 100755
--- a/bin/c
+++ b/bin/c
@@ -48,12 +48,11 @@ printErrorMsg() {
 usage() {
   local -r exit_code="${1:-0}"
   (($# > 0)) && shift
-  # shellcheck disable=SC2015
-  [ "$exit_code" != 0 ] && local -r out=/dev/stderr || local -r out=/dev/stdout
+  local -r out=$(((exit_code != 0) + 1))
 
-  (($# > 0)) && printErrorMsg "$*" >"$out"
+  (($# > 0)) && printErrorMsg "$*" >&"$out"
 
-  cat >"$out" <<EOF
+  cat >&"$out" <<EOF
 Usage: ${PROG} [OPTION]... [command [command_args ...]]
 Run command and put output to system clipper.
 If no command is specified, read from stdin(pipe).
diff --git a/bin/cp-into-docker-run b/bin/cp-into-docker-run
index 552b23f1..fc4af8f8 100755
--- a/bin/cp-into-docker-run
+++ b/bin/cp-into-docker-run
@@ -66,14 +66,13 @@ portableReadLink() {
 usage() {
   local -r exit_code="${1:-0}"
   (($# > 0)) && shift
-  # shellcheck disable=SC2015
-  [ "$exit_code" != 0 ] && local -r out=/dev/stderr || local -r out=/dev/stdout
+  local -r out=$(((exit_code != 0) + 1))
 
   # NOTE: $'foo' is the escape sequence syntax of bash
   local nl=$'\n' # new line
-  (($# > 0)) && redPrint "$*$nl" >"$out"
+  (($# > 0)) && redPrint "$*$nl" >&"$out"
 
-  cat >"$out" <<EOF
+  cat >&"$out" <<EOF
 Usage: ${PROG} [OPTION]... command [command-args]...
 
 Copy the command into docker container
diff --git a/bin/find-in-jars b/bin/find-in-jars
index 5ff3e892..cd69bee5 100755
--- a/bin/find-in-jars
+++ b/bin/find-in-jars
@@ -41,7 +41,6 @@ readonly PROG_VERSION='2.6.0-dev'
 ################################################################################
 
 readonly red='\033[1;31m' normal='\033[0m'
-readonly jar_color='\033[1;35m' sep_color='\033[1;32m'
 
 # How to delete line with echo?
 # https://unix.stackexchange.com/questions/26576
@@ -95,14 +94,13 @@ die() {
 usage() {
   local -r exit_code="${1:-0}"
   (($# > 0)) && shift
-  # shellcheck disable=SC2015
-  [ "$exit_code" != 0 ] && local -r out=/dev/stderr || local -r out=/dev/stdout
+  local -r out=$(((exit_code != 0) + 1))
 
   # NOTE: $'foo' is the escape sequence syntax of bash
   local -r nl=$'\n' # new line
-  (($# > 0)) && redPrint "$*$nl" >"$out"
+  (($# > 0)) && redPrint "$*$nl" >&"$out"
 
-  cat >"$out" <<EOF
+  cat >&"$out" <<EOF
 Usage: ${PROG} [OPTION]... PATTERN
 
 Find files in the jar files under specified directory,
@@ -355,10 +353,12 @@ searchJarFiles() {
   printf '%s\n' "$jar_files"
 }
 
+readonly jar_color='\033[1;35m' sep_color='\033[1;32m'
+
 __outputResultOfJarFile() {
   local jar_file="$1" file
   # shellcheck disable=SC2206
-  local grep_opt_args=($regex_mode ${ignore_case_option:-} ${grep_color_option:-} -- "$pattern")
+  local grep_opt_args=("$regex_mode" ${ignore_case_option:-} ${grep_color_option:-} -- "$pattern")
 
   if $only_print_file_name; then
     local matched=false
diff --git a/bin/rp b/bin/rp
index da277761..a9f7e859 100755
--- a/bin/rp
+++ b/bin/rp
@@ -71,14 +71,13 @@ portableRelPath() {
 usage() {
   local -r exit_code="${1:-0}"
   (($# > 0)) && shift
-  # shellcheck disable=SC2015
-  [ "$exit_code" != 0 ] && local -r out=/dev/stderr || local -r out=/dev/stdout
+  local -r out=$(((exit_code != 0) + 1))
 
   # NOTE: $'foo' is the escape sequence syntax of bash
   local nl=$'\n' # new line
-  (($# > 0)) && redPrint "$*$nl" >"$out"
+  (($# > 0)) && redPrint "$*$nl" >&"$out"
 
-  cat >"$out" <<EOF
+  cat >&"$out" <<EOF
 Usage: ${PROG} [OPTION]... [FILE]...
 convert to Relative Path.
 
diff --git a/bin/show-busy-java-threads b/bin/show-busy-java-threads
index 1fa90961..777660ae 100755
--- a/bin/show-busy-java-threads
+++ b/bin/show-busy-java-threads
@@ -149,12 +149,11 @@ printCallingCommandLine() {
 usage() {
   local -r exit_code="${1:-0}"
   (($# > 0)) && shift
-  # shellcheck disable=SC2015
-  [ "$exit_code" != 0 ] && local -r out=/dev/stderr || local -r out=/dev/stdout
+  local -r out=$(((exit_code != 0) + 1))
 
-  (($# > 0)) && colorPrint 31 "$*$nl" >"$out"
+  (($# > 0)) && colorPrint 31 "$*$nl" >&"$out"
 
-  cat >"$out" <<EOF
+  cat >&"$out" <<EOF
 Usage: ${PROG} [OPTION]... [delay [count]]
 Find out the highest cpu consumed threads of java processes,
 and print the stack of these threads.
diff --git a/bin/uq b/bin/uq
index 8f833f6b..712bbc46 100755
--- a/bin/uq
+++ b/bin/uq
@@ -87,12 +87,11 @@ convertHumanReadableSizeToSize() {
 usage() {
   local -r exit_code="${1:-0}"
   (($# > 0)) && shift
-  # shellcheck disable=SC2015
-  [ "$exit_code" != 0 ] && local -r out=/dev/stderr || local -r out=/dev/stdout
+  local -r out=$(((exit_code != 0) + 1))
 
-  (($# > 0)) && redPrint "$*$nl" >"$out"
+  (($# > 0)) && redPrint "$*$nl" >&"$out"
 
-  cat >"$out" <<EOF
+  cat >&"$out" <<EOF
 Usage: ${PROG} [OPTION]... [INPUT [OUTPUT]]
 Filter lines from INPUT (or standard input), writing to OUTPUT (or standard output).
 Same as \`uniq\` command in core utils,
diff --git a/bin/xpl b/bin/xpl
index 38b92461..4c1b7a28 100755
--- a/bin/xpl
+++ b/bin/xpl
@@ -37,12 +37,11 @@ readonly PROG_VERSION='2.6.0-dev'
 usage() {
   local -r exit_code="${1:-0}"
   (($# > 0)) && shift
-  # shellcheck disable=SC2015
-  [ "$exit_code" != 0 ] && local -r out=/dev/stderr || local -r out=/dev/stdout
+  local -r out=$(((exit_code != 0) + 1))
 
-  (($# > 0)) && printf '%s\n\n' "$*" >"$out"
+  (($# > 0)) && printf '%s\n\n' "$*" >&"$out"
 
-  cat <<EOF
+  cat >&"$out" <<EOF
 Usage: ${PROG} [OPTION] [FILE]...
 Open file in file explorer.
 Example: ${PROG} file.txt