server : add pidfile option

So we can track the pid of this process

Signed-off-by: Eric Curtin <[email protected]>

Author: ericcurtin

common/arg.cpp

@@ -3373,5 +3373,9 @@ common_params_context common_params_parser_init(common_params & params, llama_ex
         }
     ).set_examples({LLAMA_EXAMPLE_SERVER}));
 
+    add_opt(common_arg({ "--pidfile" }, "FILE", "path to PID file for server process",
+                       [](common_params & params, const std::string & value) { params.pidfile = value; })
+                .set_examples({ LLAMA_EXAMPLE_SERVER }));
+
     return ctx_arg;
 }

common/common.h

@@ -366,6 +366,7 @@ struct common_params {
     std::string hostname      = "127.0.0.1";
     std::string public_path   = "";                                                                         // NOLINT
     std::string chat_template = "";                                                                         // NOLINT
+    std::string             pidfile   = "";  // path to PID file for server process                           // NOLINT
     bool use_jinja = false;                                                                                 // NOLINT
     bool enable_chat_template = true;
     common_reasoning_format reasoning_format = COMMON_REASONING_FORMAT_DEEPSEEK;

tools/server/server.cpp

@@ -3691,6 +3691,19 @@ inline void signal_handler(int signal) {
     shutdown_handler(signal);
 }
 
+static int create_pidfile(const std::string & pidfile) {
+    FILE * f = fopen(pidfile.c_str(), "w");
+    if (!f) {
+        LOG_ERR("Unable to open PID file: %s\n", pidfile.c_str());
+        return -1;
+    }
+
+    fprintf(f, "%d\n", getpid());
+    fclose(f);
+
+    return 0;
+}
+
 int main(int argc, char ** argv) {
     // own arguments required by this example
     common_params params;
@@ -3699,6 +3712,7 @@ int main(int argc, char ** argv) {
         return 1;
     }
 
+    create_pidfile(params.pidfile);
     common_init();
 
     // struct that contains llama context and inference