Mechanism for enabling emulation system users to directly invoke a number of host system facilities for executing host procedures either synchronously or asynchronously in a secure manner through automatically created shell mechanisms

A host data processing system which includes a plurality of input/output devices operates under the control of an enhanced version of the UNIX operating system. The host system includes an emulator which runs as an application process for executing user emulated system (ES) application programs. The emulator includes a number of emulated system executive service components operating in shared memory and an interpreter, an emulator monitor call unit (EMCU) and a number of server facilities operating in the host memory. The ES executive service command handler component is extended to accommodate a number of dual decor commands which invoke host system facilities to execute terminal based commands either synchronously or asynchronously through the automatic creation of host shell mechanisms directly accessible by emulated system users. The server facilities include a network terminal driver (NTD) server for executing emulated system user terminal requests through host system drivers. Additionally, the NTD server includes mechanisms enabling a user to have direct terminal access to host facilities for executing procedures through such shell mechanisms. The mechanisms perform trusted user level validation when each dual decor command is issued and the shell mechanisms use the host access control mechanisms for checking access when the procedure is executed preventing both unauthorized user access and compromises in user data through the improper use of dual decor commands.