Operating System Management

• in computer programming, a process is an instance of a computer program that is being currently executed.

• A computer program is a passive collection of instructions, while a process is the actual execution of those instruction when operating system allocates the resources(Memory & processor time). several processes may be associated with the same program.

• For example : a user may working on number of MS word documents simultaneously.

• A process can be user application program Or system process. operating system is responsible to manage both these processes.

• A multitasking operating system rapidly switches the CPU execution time between the different processes currently being executed. although, CPU executes only one process at a time but due to switching it creates an illusion that all programs(processes) are running simultaneously but that is not the case

• the process management is an important function managed by the operating system. the CPU can execute only one process at a time. therefore, operating system has to decide the schedule for process, order of execution for different processes at various stages and the CPU time to be allocated.

• the program execution needs resources in terms of memory and the CPU’s processing time. the operating system manages the memory of the computer system by allocating main memory to different process currently under execution at various stages.

• the main memory of also needs to be reallocated from the process that is already terminated. memory is an important limited resource and operating system manages this by allocation and reallocating the memory from terminated process to the new processes

• A file is a collection of related information. A file can be text file, image, audio, video and many more.

• the data is represented in a computer system only in a binary form. the data is stored permanently in a secondary storage devices such as hard disk

• this data is physically stored in hard disk in two states(for magnetic tapes it is south and north poles) which can be represented in the binary form in a computer system.

• the operating system is responsible for the following activities in connection with file management.

  • File creation and deletion
  • Directory creation and deletion
  • Support of primitives for manipulating files and directories
  • Mapping files onto secondary storage
  • File backup on stable(Non-volatile) storage media.

• one of the important responsibility of the operating system is to provide secure and protected runtime environment to the various process(both applications process & system processes) which are being executed on the computer system.

• the system security is another important aspect which is handily by the operating system. protecting system against unauthorized access can be implemented by activating different security features of the operating system.

• A command interpreter is a program which reads the instructions given by the user. it then translates these instructions into the context of the operating system followed by the execution. command interpreter is also known as “shell”

• A command interpreter is the part of a computer operating system that understand and executes commands that are entered interactively by a user or from a program.

• A command interpreter is an interface between system and the user. there are two types of user interface:
  • command line interface
  • Graphical User Interface(GUI)