diff --git a/case-lib/hijack.sh b/case-lib/hijack.sh
index 25b3690a..0f951b79 100644
--- a/case-lib/hijack.sh
+++ b/case-lib/hijack.sh
@@ -64,13 +64,10 @@ function func_exit_handler()
 
     # get ps command result as list
     local -a cmd_lst
-    # $$ as current script pid
-    # NOTICE: already test with $BASHPID:
-    # it can output the same result of $$
-    # but the result could not be stored in the array
-    readarray -t cmd_lst < <(pgrep -P $$ -a|grep -v "$SCRIPT_NAME")
+    # can't run pgrep in any subshell because the latter would pollute the list
+    if pgrep -P $$ -a > "$LOG_ROOT/children_left.txt"; then
+        readarray -t cmd_lst < "$LOG_ROOT/children_left.txt"
     # now force kill target process which maybe block the script quit
-    if [ ${#cmd_lst[@]} -gt 0 ]; then
         local line
         dlogw "Process(es) started by $SCRIPT_NAME are still active, kill these process(es):"
         for line in "${cmd_lst[@]}"
@@ -79,6 +76,8 @@ function func_exit_handler()
             dlogw "Kill cmd:'${line#* }' by kill -9"
             kill -9 "${line%% *}"
         done
+    else
+        rm  "$LOG_ROOT/children_left.txt"
     fi
 
     # check if function already defined.
diff --git a/case-lib/lib.sh b/case-lib/lib.sh
index 074ea313..5a7982db 100644
--- a/case-lib/lib.sh
+++ b/case-lib/lib.sh
@@ -5,7 +5,7 @@ SCRIPT_HOME="$(dirname "$0")"
 # get test-case parent folder name
 SCRIPT_HOME=$(cd "$SCRIPT_HOME/.." && pwd)
 # shellcheck disable=SC2034 # external script can use it
-SCRIPT_NAME="$0"  # get test-case script load name
+: "${SCRIPT_NAME:="$0"}"  # get test-case script load name
 # shellcheck disable=SC2034 # external script can use it
 SCRIPT_PRAM="$*"  # get test-case parameter
 
diff --git a/case-lib/opt.sh b/case-lib/opt.sh
index 593450f3..54296bbc 100644
--- a/case-lib/opt.sh
+++ b/case-lib/opt.sh
@@ -31,7 +31,7 @@ func_opt_parse_option()
 
     _func_case_dump_descption()
     {
-         grep '^##' "$SCRIPT_NAME"|sed 's/^##//g'
+         grep '^##' "$0"|sed 's/^##//g'
     }
 
     # Asks getopt to validate command line input and generate $_op_temp_script
diff --git a/test-case/check-playback.sh b/test-case/check-playback.sh
index 08d536b7..81dfd8b0 100755
--- a/test-case/check-playback.sh
+++ b/test-case/check-playback.sh
@@ -18,6 +18,7 @@
 
 set -e
 
+SCRIPT_NAME=BOGUS-check-playback
 # shellcheck source=case-lib/lib.sh
 source "$(dirname "${BASH_SOURCE[0]}")"/../case-lib/lib.sh