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Guilherme Mazui

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What is the Difference Between System Call and Library Call?

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The main differences between system calls and library calls are as follows:

  1. Execution: System calls are executed in kernel mode and allow a program to enter kernel mode and access hardware resources, while library calls are executed in user space and are provided by programming libraries to complete a task.
  2. Privileges: System calls have more privileges than library calls because they run in supervisory mode, whereas library calls have less privileges because they run in user mode only.
  3. Functionality: System calls provide an API for user programs to request services from the operating system, such as memory management, process management, and file I/O. Library calls, on the other hand, are functions provided by programming libraries to perform specific tasks, such as mathematical computations, time and date calculations, and string manipulations.
  4. Dependency: Library calls may rely on system calls to complete their tasks, but system calls do not depend on library calls.
  5. Portability: System calls are not portable, as they are specific to the operating system, while library calls are portable and can be used across different operating systems.
  6. Examples: Some examples of system calls include cd(), fork(), and open(), while examples of library calls include fopen(), strcmp(), and memcpy.

In summary, system calls facilitate direct interaction with the operating system kernel and access to privileged services, while library calls provide a flexible and modular approach to software development by offering various functions and routines to complete tasks.

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  • What is the Difference Between System Call and Library Call?
  • Comparative Table: System Call vs Library Call

    • Comparative Table: System Call vs Library Call

    Here is a table comparing the differences between system calls and library calls:

    Feature System Call Library Call
    Mode of Execution Kernel mode User mode
    Mode Switching Switches from user mode to kernel mode No switching from user mode to kernel mode
    Direct Interaction Direct interaction with the operating system kernel No direct interaction with the operating system kernel
    Access to Hardware and Memory Direct access to hardware and memory resources Indirect access to hardware and memory resources
    Portability Not portable Portable
    Privileges Has more privileges than library calls Has fewer privileges than system calls
    Handling of Errors Often return error codes or set specific error flags May return error codes or use exceptions, depending on the programming language or library design
    Example fork(), exec() fopen(), fclose(), scanf(), printf()

    System calls are requests made by a program to enter kernel mode to access a process, while library calls are requests made by a program to access a library function defined in a programming library. System calls facilitate direct interaction with the operating system kernel and access to privileged services, while library calls provide a flexible and modular approach to software development.

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    Guilherme Mazui

    Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.