User programs can invoke operating system services either directly or through library programs. The system call interface is the boundary with the user and allows higher-level software to gain access to specific kernel functions. At the other end, the operating system contains primitive routines that interact directly with the hardware. Between these two interfaces, the system is divided into two main parts, one concerned with process control and the other concerned with file management and I/O. The process control sub-system is is responsible for memory management, the scheduling and dispatching of processes, and the synchronization and interprocess communication of processes. The file system exchanges data between memory and external devices utilising the device drivers. For block oriented transfers, a disk cache is used: a system buffer in main memory is placed between the user address space and the external device.
Fig 2 Traditional Unix kernel
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In order to legally be called a "Unix" system, operating systems must undergo a rigorous and expensive certification procedure. "Unix-like" refers to systems that have an architecture similar to Unix, but have not undergone certification.
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Indefinite. It is dependent on the computer architecture and the version being used.
No. Linux is a free, open-source version of UNIX. Many of DOS's commands were based on UNIX commands, but the underlying operating system is much more powerful than DOS.
To complex to answer completely here - see related link.
)With a neat diagram explain different layer of Unix OS? Also explain interaction between Shell an kernel using any suitable commands. or Architecture of Unix. Ans- The part of UNIX that manages the hardware and the executing processes is called the kernel. The kernel is a collection of programs written in C which directly communicate with the hardware. Each hardware device is viewed as a file and is called a device file. This allows the same simple method of reading and writing files to be used to access each hardware device. The file system manages read and write access to user data and to devices, such as printers, attached to the system. It implements security controls to protect the safety and privacy of information. In executing processes the kernel allocates resources, including use of the CPU and mediates accesses to the hardware. The user commands are translated into action by the shell which acts as an interpreter. The shell forms the outer part of the operating system and forms the interface between the user and the kernel. For each user logged in, there is shell in action. When a command is given by the user, it is examined by the shell and communicated to the kernel for execution. The functions used to communicate with the kernel are called system calls and are built into the kernel. The system calls are in all the flavors of UNIX are the same. Hence, software developed on one UNIX system can be easily run on another UNIX system. UNIX's layered design insulates the application from the different types of hardware. This allows the software developer to support the single application on multiple hardware types with minimal effort. The application writer has lower development costs and a larger potential customer base. Users not only have more applications available, but can rely on being able to use the same applications on different computer hardware.
Both Windows and Unix based operating systems will continue to evolve with hardware. Currently, 64-bit architecture is becoming more common and will slowly replace 32-bit architecture. Given time, 128-bit architecture will likely replace 64-bit, and so on.
UUCP is the abbriviation of Unix to Unix copy. It is worldwide email system called UUCP or Unix to Unix copy.This email system was developed for the operating system called Unix.
No, but Linux is based on Unix since Linux is a Unix clone.
Unix work is performed by users of the unix system, for application and system programs, or anything that requires a Unix system.
A computer that runs Unix.