NSSM is a service helper program similar to srvany and cygrunsrv. It can start any application (such as console) as an NT service and will restart the service if it fails for any reason.
NSSM also has a graphical service installer and remover.
This is a fork of NSSM
Binary files you can find in releases here
Original code: https://git.nssm.cc/nssm/nssm by Iain Patterson
Documentation: Usage, Commands
In the usage notes below, arguments to the program may be written in angle brackets and/or square brackets. means you must insert the appropriate string and [] means the string is optional. See the examples below...
Note that everywhere appears you may substitute the service's display name.
To install a service, run
nssm install <servicename>
You will be prompted to enter the full path to the application you wish to run and any command line options to pass to that application.
Use the system service manager (services.msc) to control advanced service properties such as startup method and desktop interaction. NSSM may support these options at a later time...
To install a service, run
nssm install <servicename> <application> [<options>]
NSSM will then attempt to install a service which runs the named application with the given options (if you specified any).
Don't forget to enclose paths in "quotes" if they contain spaces!
If you want to include quotes in the options you will need to """quote""" the quotes.
NSSM will launch the application listed in the registry when you send it a start signal and will terminate it when you send a stop signal. So far, so much like srvany. But NSSM is the Non-Sucking service manager and can take action if/when the application dies.
With no configuration from you, NSSM will try to restart itself if it notices that the application died but you didn't send it a stop signal. NSSM will keep trying, pausing between each attempt, until the service is successfully started or you send it a stop signal.
NSSM will pause an increasingly longer time between subsequent restart attempts if the service fails to start in a timely manner, up to a maximum of four minutes. This is so it does not consume an excessive amount of CPU time trying to start a failed application over and over again. If you identify the cause of the failure and don't want to wait you can use the Windows service console (where the service will be shown in Paused state) to send a continue signal to NSSM and it will retry within a few seconds.
By default, NSSM defines "a timely manner" to be within 1500 milliseconds. You can change the threshold for the service by setting the number of milliseconds as a REG_DWORD value in the registry at HKLM\SYSTEM\CurrentControlSet\Services<service>\Parameters\AppThrottle.
Alternatively, NSSM can pause for a configurable amount of time before attempting to restart the application even if it successfully ran for the amount of time specified by AppThrottle. NSSM will consult the REG_DWORD value at HKLM\SYSTEM\CurrentControlSet\Services<service>\Parameters\AppRestartDelay for the number of milliseconds to wait before attempting a restart. If AppRestartDelay is set and the application is determined to be subject to throttling, NSSM will pause the service for whichever is longer of the configured restart delay and the calculated throttle period.
If AppRestartDelay is missing or invalid, only throttling will be applied.
NSSM will look in the registry under HKLM\SYSTEM\CurrentControlSet\Services<service>\Parameters\AppExit for string (REG_EXPAND_SZ) values corresponding to the exit code of the application. If the application exited with code 1, for instance, NSSM will look for a string value under AppExit called "1" or, if it does not find it, will fall back to the AppExit (Default) value. You can find out the exit code for the application by consulting the system event log. NSSM will log the exit code when the application exits.
Based on the data found in the registry, NSSM will take one of three actions:
If the value data is "Restart" NSSM will try to restart the application as described above. This is its default behaviour.
If the value data is "Ignore" NSSM will not try to restart the application but will continue running itself. This emulates the (usually undesirable) behaviour of srvany. The Windows Services console would show the service as still running even though the application has exited.
If the value data is "Exit" NSSM will exit gracefully. The Windows Services console would show the service as stopped. If you wish to provide finer-grained control over service recovery you should use this code and edit the failure action manually. Please note that Windows versions prior to Vista will not consider such an exit to be a failure. On older versions of Windows you should use "Suicide" instead.
If the value data is "Suicide" NSSM will simulate a crash and exit without informing the service manager. This option should only be used for pre-Vista systems where you wish to apply a service recovery action. Note that if the monitored application exits with code 0, NSSM will only honour a request to suicide if you explicitly configure a registry key for exit code 0. If only the default action is set to Suicide NSSM will instead exit gracefully.
NSSM can set the priority class of the managed application. NSSM will look in the registry under HKLM\SYSTEM\CurrentControlSet\Services<service>\Parameters for the REG_DWORD entry AppPriority. Valid values correspond to arguments to SetPriorityClass(). If AppPriority() is missing or invalid the application will be launched with normal priority.
NSSM can set the CPU affinity of the managed application. NSSM will look in the registry under HKLM\SYSTEM\CurrentControlSet\Services<service>\Parameters for the REG_SZ entry AppAffinity. It should specify a comma-separated listed of zero-indexed processor IDs. A range of processors may optionally be specified with a dash. No other characters are allowed in the string.
For example, to specify the first; second; third and fifth CPUs, an appropriate AppAffinity would be 0-2,4.
If AppAffinity is missing or invalid, NSSM will not attempt to restrict the application to specific CPUs.
Note that the 64-bit version of NSSM can configure a maximum of 64 CPUs in this way and that the 32-bit version can configure a maxium of 32 CPUs even when running on 64-bit Windows.
When stopping a service NSSM will attempt several different methods of killing the monitored application, each of which can be disabled if necessary.
First NSSM will attempt to generate a Control-C event and send it to the application's console. Batch scripts or console applications may intercept the event and shut themselves down gracefully. GUI applications do not have consoles and will not respond to this method.
Secondly NSSM will enumerate all windows created by the application and send them a WM_CLOSE message, requesting a graceful exit.
Thirdly NSSM will enumerate all threads created by the application and send them a WM_QUIT message, requesting a graceful exit. Not all applications' threads have message queues; those which do not will not respond to this method.
Finally NSSM will call TerminateProcess() to request that the operating system forcibly terminate the application. TerminateProcess() cannot be trapped or ignored, so in most circumstances the application will be killed. However, there is no guarantee that it will have a chance to perform any tidyup operations before it exits.
Any or all of the methods above may be disabled. NSSM will look for the HKLM\SYSTEM\CurrentControlSet\Services<service>\Parameters\AppStopMethodSkip registry value which should be of type REG_DWORD set to a bit field describing which methods should not be applied.
If AppStopMethodSkip includes 1, Control-C events will not be generated. If AppStopMethodSkip includes 2, WM_CLOSE messages will not be posted. If AppStopMethodSkip includes 4, WM_QUIT messages will not be posted. If AppStopMethodSkip includes 8, TerminateProcess() will not be called.
If, for example, you knew that an application did not respond to Control-C events and did not have a thread message queue, you could set AppStopMethodSkip to 5 and NSSM would not attempt to use those methods to stop the application.
Take great care when including 8 in the value of AppStopMethodSkip. If NSSM does not call TerminateProcess() it is possible that the application will not exit when the service stops.
By default NSSM will allow processes 1500ms to respond to each of the methods described above before proceeding to the next one. The timeout can be configured on a per-method basis by creating REG_DWORD entries in the registry under HKLM\SYSTEM\CurrentControlSet\Services<service>\Parameters.
AppStopMethodConsole AppStopMethodWindow AppStopMethodThreads
Each value should be set to the number of milliseconds to wait. Please note that the timeout applies to each process in the application's process tree, so the actual time to shutdown may be longer than the sum of all configured timeouts if the application spawns multiple subprocesses.
To skip applying the above stop methods to all processes in the application's process tree, applying them only to the original application process, set the HKLM\SYSTEM\CurrentControlSet\Services<service>\Parameters\AppKillProcessTree registry value, which should be of type REG_DWORD, to 0.
By default, NSSM will create a console window so that applications which are capable of reading user input can do so - subject to the service being allowed to interact with the desktop.
Creation of the console can be suppressed by setting the integer (REG_DWORD) HKLM\SYSTEM\CurrentControlSet\Services<service>\Parameters\AppNoConsole registry value to 1.
NSSM can redirect the managed application's I/O to any path capable of being opened by CreateFile(). This enables, for example, capturing the log output of an application which would otherwise only write to the console or accepting input from a serial port.
NSSM will look in the registry under HKLM\SYSTEM\CurrentControlSet\Services<service>\Parameters for the keys corresponding to arguments to CreateFile(). All are optional. If no path is given for a particular stream it will not be redirected. If a path is given but any of the other values are omitted they will be receive sensible defaults.
AppStdin: Path to receive input. AppStdout: Path to receive output. AppStderr: Path to receive error output.
Parameters for CreateFile() are providing with the "AppStdinShareMode", "AppStdinCreationDisposition" and "AppStdinFlagsAndAttributes" values (and analogously for stdout and stderr).
In general, if you want the service to log its output, set AppStdout and AppStderr to the same path, eg C:\Users\Public\service.log, and it should work. Remember, however, that the path must be accessible to the user running the service.
When using I/O redirection, NSSM can rotate existing output files prior to opening stdout and/or stderr. An existing file will be renamed with a suffix based on the file's last write time, to millisecond precision. For example, the file nssm.log might be rotated to nssm-20131221T113939.457.log.
NSSM will look in the registry under HKLM\SYSTEM\CurrentControlSet\Services<service>\Parameters for REG_DWORD entries which control how rotation happens.
If AppRotateFiles is missing or set to 0, rotation is disabled. Any non-zero value enables rotation.
If AppRotateSeconds is non-zero, a file will not be rotated if its last write time is less than the given number of seconds in the past.
If AppRotateBytes is non-zero, a file will not be rotated if it is smaller than the given number of bytes. 64-bit file sizes can be handled by setting a non-zero value of AppRotateBytesHigh.
If AppRotateDelay is non-zero, NSSM will pause for the given number of milliseconds after rotation.
If AppStdoutCopyAndTruncate or AppStderrCopyAndTruncate are non-zero, the stdout (or stderr respectively) file will be rotated by first taking a copy of the file then truncating the original file to zero size. This allows NSSM to rotate files which are held open by other processes, preventing the usual MoveFile() from succeeding. Note that the copy process may take some time if the file is large, and will temporarily consume twice as much disk space as the original file. Note also that applications reading the log file may not notice that the file size changed. Using this option in conjunction with AppRotateDelay may help in that case.
Rotation is independent of the CreateFile() parameters used to open the files. They will be rotated regardless of whether NSSM would otherwise have appended or replaced them.
NSSM can also rotate files which hit the configured size threshold while the service is running. Additionally, you can trigger an on-demand rotation by running the command
nssm rotate <servicename>
On-demand rotations will happen after the next line of data is read from the managed application, regardless of the value of AppRotateBytes. Be aware that if the application is not particularly verbose the rotation may not happen for some time.
To enable online and on-demand rotation, set AppRotateOnline to a non-zero value.
Note that online rotation requires NSSM to intercept the application's I/O and create the output files on its behalf. This is more complex and error-prone than simply redirecting the I/O streams before launching the application. Therefore online rotation is not enabled by default.
When redirecting output, NSSM can prefix each line of output with a millisecond-precision timestamp, for example:
2016-09-06 10:17:09.451 Pipeline main started
To enable timestamp prefixing, set AppTimestampLog to a non-zero value.
The prefix applies to both stdout and stderr. Prefixing requires intercepting the application's I/O in the same way that online rotation does. If log rotation and timestamp prefixing are both enabled, the rotation will be online.
NSSM can replace or append to the managed application's environment. Two multi-valued string (REG_MULTI_SZ) registry values are recognised under HKLM\SYSTEM\CurrentControlSet\Services<service>\Parameters.
AppEnvironment defines a list of environment variables which will override the service's environment. AppEnvironmentExtra defines a list of environment variables which will be added to the service's environment.
Each entry in the list should be of the form KEY=VALUE. It is possible to omit the VALUE but the = symbol is mandatory.
Environment variables listed in both AppEnvironment and AppEnvironmentExtra are subject to normal expansion, so it is possible, for example, to update the system path by setting "PATH=C:\bin;%PATH%" in AppEnvironmentExtra. Variables are expanded in the order in which they appear, so if you want to include the value of one variable in another variable you should declare the dependency first.
Because variables defined in AppEnvironment override the existing environment it is not possible to refer to any variables which were previously defined.
For example, the following AppEnvironment block:
PATH=C:\Windows\System32;C:\Windows
PATH=C:\bin;%PATH%
Would result in a PATH of "C:\bin;C:\Windows\System32;C:\Windows" as expected.
Whereas the following AppEnvironment block:
PATH=C:\bin;%PATH%
Would result in a path containing only C:\bin and probably cause the application to fail to start.
Most people will want to use AppEnvironmentExtra exclusively. srvany only supports AppEnvironment.
As of version 2.25, NSSM parses AppEnvironment and AppEnvironmentExtra itself, before reading any other registry values. As a result it is now possible to refer to custom environment variables in Application, AppDirectory and other parameters.
All Windows services can be passed additional environment variables by creating a multi-valued string (REG_MULTI_SZ) registry value named HLKM\SYSTEM\CurrentControlSet\Services<service>\Environment.
The contents of this environment block will be merged into the system environment before the service starts.
Note, however, that the merged environment will be sorted alphabetically before being processed. This means that in practice you cannot set, for example, DIR=%PROGRAMFILES% in the Environment block because the environment passed to the service will not have defined %PROGRAMFILES% by the time it comes to define %DIR%. Environment variables defined in AppEnvironmentExtra do not suffer from this limitation.
As of version 2.25, NSSM can get and set the Environment block using commands similar to:
nssm get <servicename> Environment
It is worth reiterating that the Environment block is available to all Windows services, not just NSSM services.
The environment NSSM passes to the application depends on how various registry values are configured. The following flow describes how the environment is modified.
By default: The service inherits the system environment.
If \Environment is defined: The contents of Environment are MERGED into the environment.
If \Parameters\AppEnvironment is defined: The service inherits the environment specified in AppEnvironment.
If \Parameters\AppEnvironmentExtra is defined: The contents of AppEnvironmentExtra are APPENDED to the environment.
Note that AppEnvironment overrides the system environment and the merged Environment block. Note also that AppEnvironmentExtra is guaranteed to be appended to the startup environment if it is defined.
NSSM can run user-configurable commands in response to application events. These commands are referred to as "hooks" below.
All hooks are optional. Any hooks which are run will be launched with the environment configured for the service. NSSM will place additional variables into the environment which hooks can query to learn how and why they were called.
Hooks are categorised by Event and Action. Some hooks are run synchronously and some are run asynchronously. Hooks prefixed with an *asterisk are run synchronously. NSSM will wait for these hooks to complete before continuing its work. Note, however, that ALL hooks are subject to a deadline after which they will be killed, regardless of whether they are run asynchronously or not.
Event: Start - Triggered when the service is requested to start. *Action: Pre - Called before NSSM attempts to launch the application. Action: Post - Called after the application successfully starts.
Event: Stop - Triggered when the service is requested to stop. *Action: Pre - Called before NSSM attempts to kill the application.
Event: Exit - Triggered when the application exits. *Action: Post - Called after NSSM has cleaned up the application.
Event: Rotate - Triggered when online log rotation is requested. *Action: Pre - Called before NSSM rotates logs. Action: Post - Called after NSSM rotates logs.
Event: Power Action: Change - Called when the system power status has changed. Action: Resume - Called when the system has resumed from standby.
Note that there is no Stop/Post hook. This is because Exit/Post is called when the application exits, regardless of whether it did so in response to a service shutdown request. Stop/Pre is only called before a graceful shutdown attempt.
NSSM sets the environment variable NSSM_HOOK_VERSION to a positive number. Hooks can check the value of the number to determine which other environment variables are available to them.
If NSSM_HOOK_VERSION is 1 or greater, these variables are provided:
NSSM_EXE - Path to NSSM itself. NSSM_CONFIGURATION - Build information for the NSSM executable, eg 64-bit debug. NSSM_VERSION - Version of the NSSM executable. NSSM_BUILD_DATE - Build date of NSSM. NSSM_PID - Process ID of the running NSSM executable. NSSM_DEADLINE - Deadline number of milliseconds after which NSSM will kill the hook if it is still running. NSSM_SERVICE_NAME - Name of the service controlled by NSSM. NSSM_SERVICE_DISPLAYNAME - Display name of the service. NSSM_COMMAND_LINE - Command line used to launch the application. NSSM_APPLICATION_PID - Process ID of the primary application process. May be blank if the process is not running. NSSM_EVENT - Event class triggering the hook. NSSM_ACTION - Event action triggering the hook. NSSM_TRIGGER - Service control triggering the hook. May be blank if the hook was not triggered by a service control, eg Exit/Post. NSSM_LAST_CONTROL - Last service control handled by NSSM. NSSM_START_REQUESTED_COUNT - Number of times the application was requested to start. NSSM_START_COUNT - Number of times the application successfully started. NSSM_THROTTLE_COUNT - Number of times the application ran for less than the throttle period. Reset to zero on successful start or when the service is explicitly unpaused. NSSM_EXIT_COUNT - Number of times the application exited. NSSM_EXITCODE - Exit code of the application. May be blank if the application is still running or has not started yet. NSSM_RUNTIME - Number of milliseconds for which the NSSM executable has been running. NSSM_APPLICATION_RUNTIME - Number of milliseconds for which the application has been running since it was last started. May be blank if the application has not been started yet.
Future versions of NSSM may provide more environment variables, in which case NSSM_HOOK_VERSION will be set to a higher number.
Hooks are configured by creating string (REG_EXPAND_SZ) values in the registry named after the hook action and placed under HKLM\SYSTEM\CurrentControlSet\Services<service>\Parameters\AppEvents<event>.
For example the service could be configured to restart when the system resumes from standby by setting AppEvents\Power\Resume to:
%NSSM_EXE% restart %NSSM_SERVICE_NAME%
To set a hook on the command line, use
nssm set <servicename> AppEvents <event>/<action> <command>
Note that NSSM will abort the startup of the application if a Start/Pre hook returns exit code of 99.
A service will normally run hooks in the following order:
Start/Pre Start/Post Stop/Pre Exit/Post
If the application crashes and is restarted by NSSM, the order might be:
Start/Pre Start/Post Exit/Post Start/Pre Start/Post Stop/Pre Exit/Post
If NSSM is redirecting stdout or stderr it can be configured to redirect the output of any hooks it runs. Set AppRedirectHooks to 1 to enable that functionality. A hook can of course redirect its own I/O independently of NSSM.
NSSM can edit the settings of existing services with the same GUI that is used to install them. Run
nssm edit <servicename>
to bring up the GUI.
NSSM offers limited editing capabilities for services other than those which run NSSM itself. When NSSM is asked to edit a service which does not have the App* registry settings described above, the GUI will allow editing only system settings such as the service display name and description.
NSSM can retrieve or set individual service parameters from the command line. In general the syntax is as follows, though see below for exceptions.
nssm get <servicename> <parameter>
nssm set <servicename> <parameter> <value>
Parameters can also be reset to their default values.
nssm reset <servicename> <parameter>
The parameter names recognised by NSSM are the same as the registry entry names described above, eg AppDirectory.
NSSM offers limited editing capabilities for Services other than those which run NSSM itself. The parameters recognised are as follows:
Description: Service description. DisplayName: Service display name. Environment: Service merged environment. ImagePath: Path to the service executable. ObjectName: User account which runs the service. Name: Service key name. Start: Service startup type. Type: Service type.
These correspond to the registry values under the service's key HKLM\SYSTEM\CurrentControlSet\Services<service>.
Note that NSSM will concatenate all arguments passed on the command line with spaces to form the value to set. Thus the following two invocations would have the same effect.
nssm set <servicename> Description "NSSM managed service"
nssm set <servicename> Description NSSM managed service
The AppEnvironment, AppEnvironmentExtra and Environment parameters recognise an additional argument when querying the environment. The following syntax will print all extra environment variables configured for a service
nssm get <servicename> AppEnvironmentExtra
whereas the syntax below will print only the value of the CLASSPATH variable if it is configured in the environment block, or the empty string if it is not configured.
nssm get <servicename> AppEnvironmentExtra CLASSPATH
When setting an environment block, each variable should be specified as a KEY=VALUE pair in separate command line arguments. For example:
nssm set <servicename> AppEnvironment CLASSPATH=C:\Classes TEMP=C:\Temp
Alternatively the KEY can be prefixed with a + or - symbol to respectively add or remove a pair from the block.
The following two lines set CLASSPATH and TEMP:
nssm set <servicename> AppEnvironment CLASSPATH=C:\Classes
nssm set <servicename> AppEnvironment +TEMP=C:\Temp
If the key is already present, specifying +KEY will override the value while preserving the order of keys:
nssm set <servicename> AppEnvironment +CLASSPATH=C:\NewClasses
The following syntax removes a single variable from the block while leaving any other variables in place.
nssm set <servicename> AppEnvironment -TEMP
Specifying -KEY=VALUE will remove the variable only if the existing value matches.
The following syntax would not remove TEMP=C:\Temp
nssm set <servicename> AppEnvironment -TEMP=C:\Work\Temporary
The + and - symbols are valid characters in environment variables. The syntax :KEY=VALUE is equivalent to KEY=VALUE and can be used to set variables which start with +/- or to explicitly reset the block in a script:
nssm set <servicename> AppEnvironment :CLASSPATH=C:\Classes
nssm set <servicename> AppEnvironment +TEMP=C:\Temp
The AppExit parameter requires an additional argument specifying the exit code to get or set. The default action can be specified with the string Default.
For example, to get the default exit action for a service you should run
nssm get <servicename> AppExit Default
To get the exit action when the application exits with exit code 2, run
nssm get <servicename> AppExit 2
Note that if no explicit action is configured for a specified exit code, NSSM will print the default exit action.
To set configure the service to stop when the application exits with an exit code of 2, run
nssm set <servicename> AppExit 2 Exit
The AppPriority parameter is used to set the priority class of the managed application. Valid priorities are as follows:
REALTIME_PRIORITY_CLASS HIGH_PRIORITY_CLASS ABOVE_NORMAL_PRIORITY_CLASS NORMAL_PRIORITY_CLASS BELOW_NORMAL_PRIORITY_CLASS IDLE_PRIORITY_CLASS
The DependOnGroup and DependOnService parameters are used to query or set the dependencies for the service. When setting dependencies, each service or service group (preceded with the + symbol) should be specified in separate command line arguments. For example:
nssm set <servicename> DependOnService RpcSs LanmanWorkstation
Alternatively the dependency name can be prefixed with a + or - symbol to respectively add or remove a dependency.
The following two lines set dependencies on RpcSs and LanmanWorkstation:
nssm set <servicename> DependOnService RpcSs
nssm set <servicename> DependOnService +LanmanWorkstation
The follwing syntax removes the dependency on RpcSs:
nssm set <servicename> DependOnService -RpcSs
Service groups should, strictly speaking, be prefixed with the + symbol. To specify a single dependency on a group, the + symbol can be prefixed with the : symbol.
The following lines are equivalent, and each set a dependency ONLY on NetBIOSGroup:
nssm set <servicename> DependOnGroup NetBIOSGroup
nssm set <servicename> DependOnGroup :NetBIOSGroup
nssm set <servicename> DependOnGroup :+NetBIOSGroup
Whereas these lines add to any existing dependencies:
nssm set <servicename> DependOnGroup +NetBIOSGroup
nssm set <servicename> DependOnGroup ++NetBIOSGroup
The Name parameter can only be queried, not set. It returns the service's registry key name. This may be useful to know if you take advantage of the fact that you can substitute the service's display name anywhere where the syntax calls for .
The ObjectName parameter requires an additional argument only when setting a username. The additional argument is the password of the user.
To retrieve the username, run
nssm get <servicename> ObjectName
To set the username and password, run
nssm set <servicename> ObjectName <username> <password>
Note that the rules of argument concatenation still apply. The following invocation is valid and will have the expected effect.
nssm set <servicename> ObjectName <username> correct horse battery staple
The following well-known usernames do not need a password. The password parameter can be omitted when using them:
"LocalSystem" aka "System" aka "NT Authority\System" "LocalService" aka "Local Service" aka "NT Authority\Local Service" "NetworkService" aka "Network Service" aka "NT Authority\Network Service" Virtual service account "NT Service<servicename>"
The Start parameter is used to query or set the startup type of the service. Valid service startup types are as follows:
SERVICE_AUTO_START: Automatic startup at boot. SERVICE_DELAYED_START: Delayed startup at boot. SERVICE_DEMAND_START: Manual service startup. SERVICE_DISABLED: The service is disabled.
Note that SERVICE_DELAYED_START is not supported on versions of Windows prior to Vista. NSSM will set the service to automatic startup if delayed start is unavailable.
The Type parameter is used to query or set the service type. NSSM recognises all currently documented service types but will only allow setting one of two types:
SERVICE_WIN32_OWN_PROCESS: A standalone service. This is the default. SERVICE_INTERACTIVE_PROCESS: A service which can interact with the desktop.
Note that a service may only be configured as interactive if it runs under the LocalSystem account. The safe way to configure an interactive service is in two stages as follows.
nssm reset <servicename> ObjectName
nssm set <servicename> Type SERVICE_INTERACTIVE_PROCESS
NSSM offers rudimentary service control features.
nssm start <servicename>
nssm restart <servicename>
nssm stop <servicename>
nssm status <servicename>
nssm statuscode <servicename>
The output of "nssm status" and "nssm statuscode" is a string representing the service state, eg SERVICE_RUNNING.
The exit code of "nssm status" will be 0 if the status was succesfully retrieved. If the exit code is not zero there was an error.
The exit code of "nssm statuscode" will be the numeric value of the service state, eg 4 for SERVICE_RUNNING. Zero is not a valid service state code. If the exit code is zero there was an error.
NSSM can also remove services. Run
nssm remove <servicename>
to remove a service. You will prompted for confirmation before the service is removed. Try not to remove essential system services...
To remove a service without confirmation from the GUI, run
nssm remove <servicename> confirm
Try not to remove essential system services...
NSSM logs to the Windows event log. It registers itself as an event log source and uses unique event IDs for each type of message it logs. New versions may add event types but existing event IDs will never be changed.
Because of the way NSSM registers itself you should be aware that you may not be able to replace the NSSM binary if you have the event viewer open and that running multiple instances of NSSM from different locations may be confusing if they are not all the same version.
The following command will print the names of all services managed by NSSM:
nssm list
To see all services on the system, not just NSSM's, use list all:
nssm list all
The following command will print the process ID and executable path of processes started by a given service:
nssm processes <servicename>
Note that if 32-bit NSSM is run on a 64-bit system running an older version of Windows than Vista it will not be able to query the paths of 64-bit processes.
NSSM can dump commands which would recreate the configuration of a service. The output can be pasted into a batch script to back up the service or transfer to another computer.
nssm dump <servicename>
Because the service configuration may contain characters which need to be quoted or escaped from the command prompt, NSSM tries hard to produce output which will work correctly when run as a script, by adding quotes and caret escapes as appropriate.
To facilitate copying a service, the dump command accepts a second argument which specifies the name of the service to be used in the output.
nssm dump <servicename> <newname>
Lines in the dump will reference the service while showing the configuration of .
To install an Unreal Tournament server:
nssm install UT2004 c:\games\ut2004\system\ucc.exe server
To run the server as the "games" user:
nssm set UT2004 ObjectName games password
To configure the server to log to a file:
nssm set UT2004 AppStdout c:\games\ut2004\service.log
To restrict the server to a single CPU:
nssm set UT2004 AppAffinity 0
To remove the server:
nssm remove UT2004 confirm
To find out the service name of a service with a display name:
nssm get "Background Intelligent Transfer Service" Name
NSSM is known to compile with Visual Studio 2008 and later. Older Visual Studio releases may or may not work if you install an appropriate SDK and edit the nssm.vcproj and nssm.sln files to set a lower version number. They are known not to work with default settings.
NSSM will also compile with Visual Studio 2010 but the resulting executable will not run on versions of Windows older than XP SP2. If you require compatiblity with older Windows releases you should change the Platform Toolset to v90 in the General section of the project's Configuration Properties.
Thanks to Bernard Loh for finding a bug with service recovery. Thanks to Benjamin Mayrargue (www.softlion.com) for adding 64-bit support. Thanks to Joel Reingold for spotting a command line truncation bug. Thanks to Arve Knudsen for spotting that child processes of the monitored application could be left running on service shutdown, and that a missing registry value for AppDirectory confused NSSM. Thanks to Peter Wagemans and Laszlo Keresztfalvi for suggesting throttling restarts. Thanks to Eugene Lifshitz for finding an edge case in CreateProcess() and for advising how to build messages.mc correctly in paths containing spaces. Thanks to Rob Sharp for pointing out that NSSM did not respect the AppEnvironment registry value used by srvany. Thanks to Szymon Nowak for help with Windows 2000 compatibility. Thanks to François-Régis Tardy and Gildas le Nadan for French translation. Thanks to Emilio Frini for spotting that French was inadvertently set as the default language when the user's display language was not translated. Thanks to Riccardo Gusmeroli and Marco Certelli for Italian translation. Thanks to Eric Cheldelin for the inspiration to generate a Control-C event on shutdown. Thanks to Brian Baxter for suggesting how to escape quotes from the command prompt. Thanks to Russ Holmann for suggesting that the shutdown timeout be configurable. Thanks to Paul Spause for spotting a bug with default registry entries. Thanks to BUGHUNTER for spotting more GUI bugs. Thanks to Doug Watson for suggesting file rotation. Thanks to Арслан Сайдуганов for suggesting setting process priority. Thanks to Robert Middleton for suggestion and draft implementation of process affinity support. Thanks to Andrew RedzMax for suggesting an unconditional restart delay. Thanks to Bryan Senseman for noticing that applications with redirected stdout and/or stderr which attempt to read from stdin would fail. Thanks to Czenda Czendov for help with Visual Studio 2013 and Server 2012R2. Thanks to Alessandro Gherardi for reporting and draft fix of the bug whereby the second restart of the application would have a corrupted environment. Thanks to Hadrien Kohl for suggesting to disable the console window's menu. Thanks to Allen Vailliencourt for noticing bugs with configuring the service to run under a local user account. Thanks to Sam Townsend for noticing a regression with TerminateProcess(). Thanks to Barrett Lewis for suggesting the option to skip terminating the application's child processes. Thanks to Miguel Angel Terrón for suggesting copy/truncate rotation. Thanks to Yuriy Lesiuk for suggesting setting the environment before querying the registry for parameters. Thanks to Gerald Haider for noticing that installing a service with NSSM in a path containing spaces was technically a security vulnerability. Thanks to Scott Ware for reporting a crash saving the environment on XP 32-bit. Thanks to Stefan and Michael Scherer for reporting a bug writing the event messages source. Thanks to Paul Baxter for help with Visual Studio 2015. Thanks to Mathias Breiner for help with Visual Studio and some registry fixes. Thanks to David Bremner for general tidyups. Thanks to Nabil Redmann for suggesting redirecting hooks' output. Thanks to Bader Aldurai for suggesting the process tree. Thanks to Christian Long for suggesting virtual accounts. Thanks to Marcin Lewandowski for spotting a bug appending to large files. Thanks to Nicolas Ducrocq for suggesting timestamping redirected output. Thanks to Meang Akira Tanaka for suggestion and initial implementation of the statuscode command. Thanks to Kirill Kovalenko for reporting a crash with NANO server. Thanks to Connor Reynolds for spotting a potential buffer overflow. Thanks to foi for spotting a hang with 64 cores.
NSSM is public domain. You may unconditionally use it and/or its source code for any purpose you wish.