The service execution environment

Services on Windows run in a minimal environment. When a service is started, it inherits the environment of the Service Control Manager (normally the system environment) and defines HOME, LOGNAME, and TZ.

The following describes how psxrun.exe assigns values for particular environment variables:

• LOGNAME, which is based on the Windows USERNAME, is passed as an argument to the service program when a service is installed. If no user name is given, it defaults to the user LocalSystem.
• HOME is built from HOMEPATH and HOMEDRIVE, which are provided by the operating system for the specified user.
• TZ is your time zone derived from the operating system. The format is documented in the tzset() reference page.
• The PATH inherited from the Service Control Manager is copied into the environment variable _PSXLIBPATH. The contents of PATH are then converted into POSIX format.

Some system parameters, such as SYSTEMROOT and NUMBER_OF_PROCESSORS, are also available.

Interix daemons have to be installed and executed as services only if they have to run logged on with a Windows account, such as to access network resources. Otherwise, they can be run as conventional daemons using the same mechanism as conventional UNIX systems, by creating shell scripts in the /etc/rc2.d/ directory that directly start and stop the daemons. If you do this, init(1) can start the daemon when the Interix subsystem initializes. For more information, see Understanding services and daemons.