Config: Support set env_only by SRS_ENV_ONLY.

.run/env.run.xml

@@ -1,6 +1,7 @@
 <component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="env" type="CMakeRunConfiguration" factoryName="Application" PROGRAM_PARAMS="-e" REDIRECT_INPUT="false" ELEVATE="false" USE_EXTERNAL_CONSOLE="false" WORKING_DIR="file://$CMakeCurrentBuildDir$/../../../" PASS_PARENT_ENVS_2="true" PROJECT_NAME="srs" TARGET_NAME="srs" CONFIG_NAME="Debug" RUN_TARGET_PROJECT_NAME="srs" RUN_TARGET_NAME="srs">
+  <configuration default="false" name="env" type="CMakeRunConfiguration" factoryName="Application" REDIRECT_INPUT="false" ELEVATE="false" USE_EXTERNAL_CONSOLE="false" WORKING_DIR="file://$CMakeCurrentBuildDir$/../../../" PASS_PARENT_ENVS_2="true" PROJECT_NAME="srs" TARGET_NAME="srs" CONFIG_NAME="Debug" RUN_TARGET_PROJECT_NAME="srs" RUN_TARGET_NAME="srs">
     <envs>
+      <env name="SRS_ENV_ONLY" value="on" />
       <env name="SRS_LISTEN" value="1935" />
       <env name="SRS_EXPORTER_ENABLED" value="on" />
     </envs>

trunk/src/app/srs_app_config.cpp

@@ -1848,6 +1848,9 @@ srs_error_t SrsConfig::parse_options(int argc, char** argv)
     // first hello message.
     srs_trace(_srs_version);
 
+    // Config the env_only_ by env.
+    if (getenv("SRS_ENV_ONLY")) env_only_ = true;
+
     // Try config files as bellow:
     //      User specified config(not empty), like user/docker.conf
     //      If user specified *docker.conf, try *srs.conf, like user/srs.conf

trunk/src/app/srs_app_config.hpp

@@ -275,6 +275,7 @@ private:
     // Whether show SRS signature and exit.
     bool show_signature;
     // Whether only use environment variable, ignore config file.
+    // Set it by argv "-e" or env "SRS_ENV_ONLY=on".
     bool env_only_;
 // global env variables.
 private: