Vérifier si le port est libre avant de faire une connection SSH

bin/ssh-fwd

@@ -14,11 +14,17 @@ Usage: $(basename "$0") SSH_HOST LOCAL_PORT DISTANT_PORT [TARGET] [-- SSH_OPTION
 EOF
 }
 
+# Show an error
 function error {
     >&2 usage
     exit "${1:-1}"
 }
 
+# Check if TCP port number is free
+port_is_free() {
+    ! lsof -i -P -n | grep -q ':'"${1}"' (LISTEN)'
+}
+
 # Arguments
 while [[ -n $* ]]; do
     case "$1" in
@@ -54,5 +60,9 @@ ssh_com=(
 
 # Execution
 set -x
+if port_is_free "${args[1]}"; then
     "${ssh_com[@]}"
+else
+    echo "Port is not free, skipping."
+fi