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Operating-system service provie functions that are helpful to the user
- User interface, CLI,GUI,BATCH
- Program execution - able to load a program into memory and to run that program and execution
- IO operations - may involve a file or an io device
- File-system manipulation - read and write file and directories, creation and delete them
- Communication - exchange information, both same and different computer over network ( shaare memory, packets moved by the os)
- Error detection - constantly aware of possible error ( cpu and memory hardware)
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OS functions exists of ensuring the efficient operation of the sys
- Resource allocation
- accounting - to keep track of which users use how much and what kinds of computer resources
- protection and security - to protect the owners of information
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CLI - command line interpreter
- allows direct command entry
- -inplemented in kernel
- -primarily fetches a command from user and executes it
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GUI
- user friendly desktop interface
- - mouse keyboard
- -icons represent files, program, actions
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System calls
- programming interface to the services provided by the OS
- high level language C or C++
- access by API
- e.g process control, file management, device management, informations maintenance, communication
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APIs rather than system call?
- system calls are detailed and more difficult to work with
- using apis can allow programs to complie and run on other system
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e.g of API
BOOL ReadFile c (HANDLE file, LPVIOD buffer...);
return value + function name + parameters
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