diff --git a/tests/scripts/expect/posix-rcp-restoration.exp b/tests/scripts/expect/posix-rcp-restoration.exp
index 4b174c6c6..deba3c658 100755
--- a/tests/scripts/expect/posix-rcp-restoration.exp
+++ b/tests/scripts/expect/posix-rcp-restoration.exp
@@ -31,11 +31,24 @@ source "tests/scripts/expect/_common.exp"
 source "tests/scripts/expect/_multinode.exp"
 
 
+if {[info exists ::env(THREAD_VERSION)]} {
+    set ot_thread_version $::env(THREAD_VERSION)
+} else {
+    set ot_thread_version ""
+}
+
+if {[info exists ::env(OT_SIMULATION_APPS)]} {
+    set ot_simulation_apps $::env(OT_SIMULATION_APPS)
+} else {
+    set ot_simulation_apps "build/simulation/examples/apps"
+}
+
 # The expect on macOS doesn't support `try` or `file tempfile`.
 skip_on_macos
 
 file tempfile socat_out
-set socat_pid [exec socat -d -d pty,raw,echo=0 pty,raw,echo=0 >/dev/null 2>$socat_out &]
+spawn bash -c "exec socat -d -d pty,raw,echo=0 pty,raw,echo=0 >/dev/null 2>$socat_out"
+set socat_id $spawn_id
 while {true} {
     if {[exec head -n2 $socat_out | wc -l] == 2} {
         set radio_pty [exec head -n1 $socat_out | grep -o {/dev/.\+}]
@@ -48,8 +61,9 @@ while {true} {
 puts "Radio PTY: $radio_pty"
 puts "Host PTY: $host_pty"
 
-set rcp_pid [exec $::env(OT_SIMULATION_APPS)/ncp/ot-rcp 1 < $radio_pty > $radio_pty &]
-puts "RCP PID: $rcp_pid"
+spawn bash -c "exec $ot_simulation_apps/ncp/ot-rcp 1 < $radio_pty > $radio_pty"
+set rcp_id $spawn_id
+puts "RCP PID: $rcp_id"
 
 try {
     puts "Before enabling"
@@ -87,11 +101,12 @@ try {
 
     sleep 1
 
-    exec kill $rcp_pid
-    puts "Killed $rcp_pid"
+    close -i $rcp_id
+    puts "Killed $rcp_id"
     sleep 1
-    set rcp_pid [exec $::env(OT_SIMULATION_APPS)/ncp/ot-rcp 1 < $radio_pty > $radio_pty &]
-    puts "RCP PID: $rcp_pid"
+    spawn bash -c "exec $ot_simulation_apps/ncp/ot-rcp 1 < $radio_pty > $radio_pty"
+    set rcp_id $spawn_id
+    puts "RCP PID: $rcp_id"
 
     sleep 1
 
@@ -106,11 +121,12 @@ try {
 
     puts "Queued parent-to-child packets, as child"
 
-    exec kill $rcp_pid
-    puts "Killed $rcp_pid"
+    close -i $rcp_id
+    puts "Killed $rcp_id"
     sleep 1
-    set rcp_pid [exec $::env(OT_SIMULATION_APPS)/ncp/ot-rcp 2 < $radio_pty > $radio_pty &]
-    puts "RCP PID: $rcp_pid"
+    spawn bash -c "exec $ot_simulation_apps/ncp/ot-rcp 2 < $radio_pty > $radio_pty"
+    set rcp_id $spawn_id
+    puts "RCP PID: $rcp_id"
 
     spawn_node 1
     spawn_node 2 "rcp" "spinel+hdlc_uart://$host_pty"
@@ -141,11 +157,12 @@ try {
 
     sleep 1
 
-    exec kill $rcp_pid
-    puts "Killed $rcp_pid"
+    close -i $rcp_id
+    puts "Killed $rcp_id"
     sleep 1
-    set rcp_pid [exec $::env(OT_SIMULATION_APPS)/ncp/ot-rcp 2 < $radio_pty > $radio_pty &]
-    puts "RCP PID: $rcp_pid"
+    spawn bash -c "exec $ot_simulation_apps/ncp/ot-rcp 2 < $radio_pty > $radio_pty"
+    set rcp_id $spawn_id
+    puts "RCP PID: $rcp_id"
 
     sleep 1
 
@@ -156,11 +173,12 @@ try {
 
     dispose_all
 
-    exec kill $rcp_pid
-    puts "Killed $rcp_pid"
+    close -i $rcp_id
+    puts "Killed $rcp_id"
     sleep 1
-    set rcp_pid [exec $::env(OT_SIMULATION_APPS)/ncp/ot-rcp 1 < $radio_pty > $radio_pty &]
-    puts "RCP PID: $rcp_pid"
+    spawn bash -c "exec $ot_simulation_apps/ncp/ot-rcp 1 < $radio_pty > $radio_pty"
+    set rcp_id $spawn_id
+    puts "RCP PID: $rcp_id"
 
 
     puts "Many children, queued child-to-child packets"
@@ -197,11 +215,12 @@ try {
 
     sleep 1
 
-    exec kill $rcp_pid
-    puts "Killed $rcp_pid"
+    close -i $rcp_id
+    puts "Killed $rcp_id"
     sleep 1
-    set rcp_pid [exec $::env(OT_SIMULATION_APPS)/ncp/ot-rcp 1 < $radio_pty > $radio_pty &]
-    puts "RCP PID: $rcp_pid"
+    spawn bash -c "exec $ot_simulation_apps/ncp/ot-rcp 1 < $radio_pty > $radio_pty"
+    set rcp_id $spawn_id
+    puts "RCP PID: $rcp_id"
 
     sleep 1
 
@@ -215,17 +234,18 @@ try {
     switch_node 4
     send "udp send $addr(5) 11003 hello_from_node_4\n"
     expect_line "Done"
-    if {$::env(THREAD_VERSION) != "1.1"} {
+    if {$ot_thread_version != "1.1"} {
         expect "5 bytes from $addr(1) 11004 hello"
     }
 
     sleep 1
 
-    exec kill $rcp_pid
-    puts "Killed $rcp_pid"
+    close -i $rcp_id
+    puts "Killed $rcp_id"
     sleep 1
-    set rcp_pid [exec $::env(OT_SIMULATION_APPS)/ncp/ot-rcp 1 < $radio_pty > $radio_pty &]
-    puts "RCP PID: $rcp_pid"
+    spawn bash -c "exec $ot_simulation_apps/ncp/ot-rcp 1 < $radio_pty > $radio_pty"
+    set rcp_id $spawn_id
+    puts "RCP PID: $rcp_id"
 
     sleep 1
 
@@ -249,14 +269,6 @@ try {
 
     sleep 1
 
-    exec kill $rcp_pid
-    puts "Killed $rcp_pid"
-    sleep 1
-    set rcp_pid [exec $::env(OT_SIMULATION_APPS)/ncp/ot-rcp 1 < $radio_pty > $radio_pty &]
-    puts "RCP PID: $rcp_pid"
-
-    sleep 1
-
     for {set i 11} {$i <= 26} {incr i} {
         expect -re "\\| +$i \\| +-?\\d+ \\|"
     }
@@ -264,6 +276,6 @@ try {
 
     dispose_all
 } finally {
-    exec kill $rcp_pid
-    exec kill $socat_pid
+    close -i $rcp_id
+    close -i $socat_id
 }