diff --git a/contrib b/contrib
index 93c2bdf8..f0d0f372 160000
--- a/contrib
+++ b/contrib
@@ -1 +1 @@
-Subproject commit 93c2bdf8bf8df817dfa8a9b287f7614732cdb135
+Subproject commit f0d0f372b9232e241e8fd22c42a741cc9dd6a6fa
diff --git a/docs/ChangeLog.md b/docs/ChangeLog.md
index cd5db4c3..3929a40e 100644
--- a/docs/ChangeLog.md
+++ b/docs/ChangeLog.md
@@ -547,6 +547,7 @@
 - util: support `bleopt debug_idle` `#D1945` fa10184
 - global: work around bash-4.4 no-argument return in trap `#D1970` eb4ffce
 - util: replace builtin `readonly` with a shell function (requested by mozirilla213) `#D1985` xxxxxxx
+- global: avoid directly using `/dev/tty` `#D1986` xxxxxxx
 
 ## Contrib
 
diff --git a/lib/core-complete.sh b/lib/core-complete.sh
index d51d00f5..c102511b 100644
--- a/lib/core-complete.sh
+++ b/lib/core-complete.sh
@@ -1528,7 +1528,7 @@ function ble/complete/action/quote-insert.batch/proc {
   local fname_cands=$_ble_local_tmpfile
   ble/util/conditional-sync \
     'ble/complete/action/quote-insert.batch/awk < "$fname_cands"' \
-    '! ble/complete/check-cancel < /dev/tty' '' progressive-weight
+    '! ble/complete/check-cancel <&"$_ble_util_fd_stdin"' '' progressive-weight
   local ext=$?
 
   ble/util/assign/.rmtmp
diff --git a/make_command.sh b/make_command.sh
index 68863665..53feeb74 100755
--- a/make_command.sh
+++ b/make_command.sh
@@ -1129,8 +1129,15 @@ function sub:scan/check-todo-mark {
 }
 function sub:scan/a.txt {
   echo "--- $FUNCNAME ---"
-  grc --color --exclude=./{test,ext} --exclude=./lib/test-*.sh --exclude=./make_command.sh --exclude=\*.md 'a\.txt|/dev/(pts/|pty)[0-9]*' |
-    grep -Ev "$rex_grep_head#|[[:space:]]#|DEBUG_LEAKVAR"
+  grc --color --exclude={test,ext,./lib/test-\*.sh,./make_command.sh,\*.md} --exclude=check-mem.sh 'a\.txt|/dev/(pts/|pty)[0-9]*|/dev/tty' |
+    sed -E 'h;s/'"$_make_rex_escseq"'//g
+      \Z^\./memo/Zd
+    s/^[^:]*:[0-9]+:[[:space:]]*//
+      \Z^[[:space:]]*#Zd
+      \ZDEBUG_LEAKVARZd
+      \Z\[\[ -t 4 && -t 5 ]]Zd
+      \Z^ble/fd#alloc .*Zd
+      g'
 }
 
 function sub:scan/bash300bug {
diff --git a/note.txt b/note.txt
index c00c8b31..ceed588a 100644
--- a/note.txt
+++ b/note.txt
@@ -6661,6 +6661,9 @@ bash_tips
 
 2023-03-01
 
+  * global: コード中の /dev/tty は予め持っておいた fd に置き換えるべきなのでは [#D1986]
+    修正した。
+
   * util: readonly を上書きする? (reqeusted by mozirilla213) [#D1985]
     https://github.com/akinomyoga/ble.sh/issues/289
 
diff --git a/src/edit.sh b/src/edit.sh
index ea23f09d..d070b805 100644
--- a/src/edit.sh
+++ b/src/edit.sh
@@ -380,7 +380,7 @@ function ble/application/onwinch {
     if ((50200<=_ble_bash&&_ble_bash<50300)); then
       # Note: bash-5.2 では trap string / bind -x 内部で COLUMNS/LINES が更新さ
       #   れないので "$BASH" を起動して端末サイズを取得する。
-      builtin eval -- "$(ble/util/msleep 50; exec "$BASH" -O checkwinsize -c '(:); [[ $COLUMNS && $LINES ]] && printf %s "COLUMNS=$COLUMNS LINES=$LINES"' 2>/dev/tty)"
+      builtin eval -- "$(ble/util/msleep 50; exec "$BASH" -O checkwinsize -c '(:); [[ $COLUMNS && $LINES ]] && printf %s "COLUMNS=$COLUMNS LINES=$LINES"' 2>&"$_ble_util_fd_stderr")"
     else
       # 次の WINCH を待つと共にサブシェルで checkwinsize を誘発
       (ble/util/msleep 50)
@@ -737,7 +737,7 @@ function ble/prompt/unit#update/.update-dependencies {
       local ble_prompt_unit_processing=1
       "${_ble_util_set_declare[@]//NAME/ble_prompt_unit_mark}" # WA #D1570 checked
     elif ble/set#contains ble_prompt_unit_mark "$unit"; then
-      ble/util/print "ble/prompt: FATAL: detected cyclic dependency ($unit required by $ble_prompt_unit_parent)" >/dev/tty
+      ble/util/print "ble/prompt: FATAL: detected cyclic dependency ($unit required by $ble_prompt_unit_parent)" >&"$_ble_util_fd_stderr"
       return 1
     fi
     local ble_prompt_unit_parent=$unit
@@ -1640,7 +1640,7 @@ if ble/is-function ble/util/idle.push; then
       builtin exit 0 &>/dev/null
       builtin exit 0 &>/dev/null' pre-flush
     return 1 # exit に失敗した時
-  } >/dev/tty
+  } >&"$_ble_util_fd_stdout" 2>&"$_ble_util_fd_stderr"
   function ble/prompt/timeout/check {
     [[ $_ble_edit_lineno == "$_ble_prompt_timeout_lineno" ]] && return 0
     _ble_prompt_timeout_lineno=$_ble_edit_lineno
@@ -6088,7 +6088,7 @@ function ble/exec/time/times.parse-time {
   local msc=$((10#0${BASH_REMATCH[3]#?}))
   ((ret=(min*60+sec)*1000+msc))
   return 0
-} 2>/dev/tty
+} 2>&"$_ble_util_fd_stderr"
 function ble/exec/time/times.start {
   builtin times >| "$_ble_exec_time_TIMES"
 }
@@ -6442,13 +6442,13 @@ function ble-edit/exec:gexec/.TRAPDEBUG {
       local sep=${_ble_term_setaf[6]}:
       local lineno=${_ble_term_setaf[2]}${BLE_TRAP_LINENO[0]}
       local func=${_ble_term_setaf[6]}' ('${_ble_term_setaf[4]}${BLE_TRAP_FUNCNAME[0]}${1:+ $1}${_ble_term_setaf[6]}')'
-      ble/util/print "${_ble_term_setaf[9]}[SIGINT]$_ble_term_sgr0 $source$sep$lineno$func$_ble_term_sgr0" >/dev/tty
+      ble/util/print "${_ble_term_setaf[9]}[SIGINT]$_ble_term_sgr0 $source$sep$lineno$func$_ble_term_sgr0" >&"$_ble_util_fd_stderr"
       _ble_builtin_trap_postproc[_ble_trap_sig]="{ return $_ble_edit_exec_TRAPDEBUG_INT || break; } &>/dev/null"
     elif ((depth==0)) && ! ble/string#match "$_ble_trap_bash_command" '^ble-edit/exec:gexec/\.'; then
       # 一番外側で、ble-edit/exec:gexec/. 関数ではない時
       local source=${_ble_term_setaf[5]}global
       local sep=${_ble_term_setaf[6]}:
-      ble/util/print "${_ble_term_setaf[9]}[SIGINT]$_ble_term_sgr0 $source$sep$_ble_term_sgr0 $_ble_trap_bash_command" >/dev/tty
+      ble/util/print "${_ble_term_setaf[9]}[SIGINT]$_ble_term_sgr0 $source$sep$_ble_term_sgr0 $_ble_trap_bash_command" >&"$_ble_util_fd_stderr"
       _ble_builtin_trap_postproc[_ble_trap_sig]="break &>/dev/null"
     fi
 
@@ -6555,7 +6555,7 @@ function ble-edit/exec:gexec/.TRAPINT {
     _ble_edit_exec_TRAPDEBUG_INT=$ext
     ble-edit/exec:gexec/.TRAPDEBUG/trap
   else
-    _ble_builtin_trap_postproc="{ return $ext || break; } &>/dev/tty"
+    _ble_builtin_trap_postproc="{ return $ext || break; } 2>&$_ble_util_fd_stderr"
   fi
 }
 function ble-edit/exec:gexec/.TRAPINT/reset {
diff --git a/src/history.sh b/src/history.sh
index 15e7144a..b1ca9b94 100644
--- a/src/history.sh
+++ b/src/history.sh
@@ -100,7 +100,7 @@ if ((_ble_bash<40000)); then
       true 100 progressive-weight:timeout=3000:SIGKILL
     local ext=$?
     if ((ext==142)); then
-      printf 'ble.sh: timeout: builtin history %s' "$*" >/dev/tty
+      printf 'ble.sh: timeout: builtin history %s' "$*" >&"$_ble_util_fd_stderr"
       local ret=11
       ble/builtin/trap/sig#resolve SIGSEGV
       ((ext=128+ret))