👀 System Services
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System Services, also known as system utilities, provide a convenient environment for program development and execution.
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Some of them are simply user interfaces to system calls; others are considerably more complex.
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They can be divided into:
• File manipulation
• Status information sometimes stored in a file
• Programming language support
• Program loading and execution
• Communications
• Application programs -
Most users’ view of the operation system is defined by system programs, not the actual system calls
Summary
- system utilities라고도 알려진 system services는, 프로그램 개발과 실행을 위해 더 편리한 환경을 제공한다.
- 그 중 일부는 단순히 system calls에 대한 user interfaces이며, 다른 부분은 훨씬 더 복잡하다.
- OS에 대한 user의 view는 system calls이 아닌 system programs에 의해 결정된다.
📕 File management
- Create, delete, copy, rename, print, dump, list, and generally manipulate files and directories
📙 Status information
- Some ask the system for info
• date, time, amount of available memory, disk space, number of users
• Others provide detailed performance, logging, and debugging information - Typically, these programs format and print the output to the terminal or other output devices
• Some systems implement a registry
-> used to store and retrieve configuration information
📒 File modification
- Text editors to create and modify files
- Special commands to search contents of files or perform transformations of the text
📗 Programming-language support
- Compilers, assemblers, debuggers and interpreters sometimes provided
📘 Program loading and execution
- Absolute loaders, relocatable loaders, linkage editors, and overlayloaders, debugging systems for higher-level and machine language
📔 Communications
- Provide the mechanism for creating virtual connections among processes, users, and computer systems
- Allow users to send messages to one another’s screens, browse web pages, send electronic-mail messages, log in remotely, transfer files from one machine to another
📓 Application programs
- Don’t pertain to system
- Run by users
- Not typically considered part of OS
- Launched by command line, mouse click, finger poke
