diff --git a/create_usbhid.sh b/create_usbhid.sh
index 12eebd0..fcde89a 100644
--- a/create_usbhid.sh
+++ b/create_usbhid.sh
@@ -6,7 +6,7 @@
 create_hid() {
     # create gadget
     mkdir "${hid_conf_directory}"
-    cd "${hid_conf_directory}"
+    cd "${hid_conf_directory}" || return
 
     # add basic information
     echo 0x0100 > bcdDevice
@@ -61,7 +61,7 @@
     #  0x29, 0x65, //   USAGE_MAXIMUM (Keyboard Application)
     #  0x81, 0x00, //   INPUT (Data,Ary,Abs)
     #  0xc0        // END_COLLECTION
-    echo -ne '\x05\x01\x09\x06\xa1\x01\x05\x07\x19\xe0\x29\xe7\x15\x00\x25\x01\x75\x01\x95\x08\x81\x02\x95\x01\x75\x08\x81\x03\x95\x05\x75\x01\x05\x08\x19\x01\x29\x05\x91\x02\x95\x01\x75\x03\x91\x03\x95\x06\x75\x08\x15\x00\x25\x65\x05\x07\x19\x00\x29\x65\x81\x00\xc0' > functions/hid.0/report_desc
+    printf '\x05\x01\x09\x06\xa1\x01\x05\x07\x19\xe0\x29\xe7\x15\x00\x25\x01\x75\x01\x95\x08\x81\x02\x95\x01\x75\x08\x81\x03\x95\x05\x75\x01\x05\x08\x19\x01\x29\x05\x91\x02\x95\x01\x75\x03\x91\x03\x95\x06\x75\x08\x15\x00\x25\x65\x05\x07\x19\x00\x29\x65\x81\x00\xc0' > functions/hid.0/report_desc
 
     # Create HID mouse function
     mkdir functions/hid.1
@@ -109,7 +109,7 @@
     #  0x81, 0x06,       //     INPUT (Data,Var,Rel)
     #  0xc0,             //   END_COLLECTION
     #  0xc0              // END_COLLECTION
-    echo -ne '\x05\x01\x09\x02\xa1\x01\x09\x01\xa1\x00\x05\x09\x19\x01\x29\x03\x15\x00\x25\x01\x95\x03\x75\x01\x81\x02\x95\x01\x75\x05\x81\x03\x05\x01\x09\x30\x09\x31\x35\x00\x46\xff\x7f\x15\x00\x26\xff\x7f\x65\x11\x55\x00\x75\x10\x95\x02\x81\x02\x09\x38\x15\xff\x25\x01\x35\x00\x45\x00\x75\x08\x95\x01\x81\x06\xc0\xc0' > functions/hid.1/report_desc
+    printf '\x05\x01\x09\x02\xa1\x01\x09\x01\xa1\x00\x05\x09\x19\x01\x29\x03\x15\x00\x25\x01\x95\x03\x75\x01\x81\x02\x95\x01\x75\x05\x81\x03\x05\x01\x09\x30\x09\x31\x35\x00\x46\xff\x7f\x15\x00\x26\xff\x7f\x65\x11\x55\x00\x75\x10\x95\x02\x81\x02\x09\x38\x15\xff\x25\x01\x35\x00\x45\x00\x75\x08\x95\x01\x81\x06\xc0\xc0' > functions/hid.1/report_desc
 
     # Create configuration
     mkdir configs/c.1
@@ -125,13 +125,13 @@
 }
 
 connect_hid() {
-    if ! [[ `cat UDC` =~ "${dev_name}:p" ]]; then
+    if ! grep -q "${dev_name}:p" UDC; then
         i=0
         num_ports=5
         base_usb_dir="/sys/bus/platform/devices/${dev_name}/${dev_name}:p"
-        while [ $i -lt $num_ports ]; do
-            port=$(($i + 1))
-            i=$port
+        while [ "${i}" -lt "${num_ports}" ]; do
+            port=$(("${i}" + 1))
+            i="${port}"
             if [ ! -e "${base_usb_dir}${port}/gadget/suspended" ]; then
                 break
             fi
@@ -141,17 +141,15 @@
 }
 
 disconnect_hid() {
-    if [[ `cat UDC` =~ "${dev_name}:p" ]]; then
+    if grep -q "${dev_name}:p" UDC; then
         echo "" > UDC
     fi
 }
 
-original_directory="$(pwd)"
-
 if [ ! -e "${hid_conf_directory}" ]; then
     create_hid
 else
-    cd "${hid_conf_directory}"
+    cd "${hid_conf_directory}" || exit
 fi
 
 if [ "$1" = "connect" ]; then
@@ -159,7 +157,6 @@
 elif [ "$1" = "disconnect" ]; then
     disconnect_hid
 else
-    echo "Invalid option: $1. Use 'connect' or 'disconnect'."
+    echo >&2 "Invalid option: $1. Use 'connect' or 'disconnect'."
+    exit 1
 fi
-
-cd "${original_directory}"