fix clear known hosts command

dockdroid.sh

@@ -99,15 +99,37 @@ case $1 in
     ;;
 
   clear-known-hosts)
-    echo "This will clear known hosts. Please run this command as root or use sudo."
-    
-    if [ "$EUID" -ne 0 ]
+    echo "This will clear known hosts."
+
+    # EUID may not be available in all environments, instead you can use id -u to get the user ID
+    if [ "$(id -u)" -ne 0 ]
     then
+      echo "Please run as root or use sudo"
       exit 1
     fi
 
     CONTAINER_IP=$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' ${CONTAINER_NAME})
-    ssh-keygen -R ${CONTAINER_IP}
+
+    # Define known_hosts and temporary file path
+    KNOWN_HOSTS_PATH="$HOME/.ssh/known_hosts"
+    TEMP_FILE="$HOME/.ssh/temp"
+
+    # Check if the .ssh directory exists and is writable
+    if [ ! -d "$(dirname ${KNOWN_HOSTS_PATH})" ] || [ ! -w "$(dirname ${KNOWN_HOSTS_PATH})" ]; then
+      echo "The .ssh directory does not exist or is not writable"
+      exit 1
+    fi
+
+    # Check if the known_hosts file exists, if not, exit early as there's nothing to clear
+    if [ ! -f ${KNOWN_HOSTS_PATH} ]; then
+      echo "The known_hosts file does not exist. Nothing to clear."
+      exit 0
+    fi
+
+    # Create a temporary file and remove the line with CONTAINER_IP. If grep doesn't find a match, it will still create an empty file.
+    grep -v "${CONTAINER_IP}" ${KNOWN_HOSTS_PATH} > ${TEMP_FILE} || true
+
+    mv ${TEMP_FILE} ${KNOWN_HOSTS_PATH}
     ;;
 
   *)