Describe startup environment in the README.

[nssm.git] / README.txt

diff --git a/README.txt b/README.txt
index f48a7f1..224af93 100644 (file)
--- a/README.txt
+++ b/README.txt
@@ -406,6 +406,59 @@ application to fail to start.
 Most people will want to use AppEnvironmentExtra exclusively.  srvany only\r
 supports AppEnvironment.\r
 \r
+As of version 2.25, NSSM parses AppEnvironment and AppEnvironmentExtra\r
+itself, before reading any other registry values.  As a result it is now\r
+possible to refer to custom environment variables in Application,\r
+AppDirectory and other parameters.\r
+\r
+\r
+Merged service environment\r
+--------------------------\r
+All Windows services can be passed additional environment variables by\r
+creating a multi-valued string (REG_MULTI_SZ) registry value named\r
+HLKM\SYSTEM\CurrentControlSet\Services\<service>\Environment.\r
+\r
+The contents of this environment block will be merged into the system\r
+environment before the service starts.\r
+\r
+Note, however, that the merged environment will be sorted alphabetically\r
+before being processed.  This means that in practice you cannot set,\r
+for example, DIR=%PROGRAMFILES% in the Environment block because the\r
+environment passed to the service will not have defined %PROGRAMFILES%\r
+by the time it comes to define %DIR%.  Environment variables defined in\r
+AppEnvironmentExtra do not suffer from this limitation.\r
+\r
+As of version 2.25, NSSM can get and set the Environment block using\r
+commands similar to:\r
+\r
+    nssm get <servicename> Environment\r
+\r
+It is worth reiterating that the Environment block is available to all\r
+Windows services, not just NSSM services.\r
+\r
+\r
+Service startup environment\r
+---------------------------\r
+The environment NSSM passes to the application depends on how various\r
+registry values are configured.  The following flow describes how the\r
+environment is modified.\r
+\r
+By default:\r
+    The service inherits the system environment.\r
+\r
+If <service>\Environment is defined:\r
+    The contents of Environment are MERGED into the environment.\r
+\r
+If <service>\Parameters\AppEnvironment is defined:\r
+    The service inherits the environment specified in AppEnvironment.\r
+\r
+If <service>\Parameters\AppEnvironmentExtra is defined:\r
+    The contents of AppEnvironmentExtra are APPENDED to the environment.\r
+\r
+Note that AppEnvironment overrides the system environment and the\r
+merged Environment block.  Note also that AppEnvironmentExtra is\r
+guaranteed to be appended to the startup environment if it is defined.\r
+\r
 \r
 Event hooks\r
 -----------\r
@@ -555,6 +608,7 @@ run NSSM itself.  The parameters recognised are as follows:
 \r
   Description: Service description.\r
   DisplayName: Service display name.\r
+  Environment: Service merged environment.\r
   ImagePath: Path to the service executable.\r
   ObjectName: User account which runs the service.\r
   Name: Service key name.\r