==Categories of system calls==System calls can be roughly grouped into five major categories:# Process Control#* load#* execute#* end,abort#* create process (for example, codice_1 on Unix-like systems, or codice_15 in the Windows NT Native API)#* terminate process#* get/set process attributes#* wait for time, wait event, signal event#* allocate and free memory# File management#* create file, delete file#* open, close#* read, write, reposition#* get/set file attributes# Device Management#* request device, release device#* read, write, reposition#* get/set device attributes#* logically attach or detach devices# Information Maintenance#* get/set time or date#* get/set system data#* get/set process, file, or device attributes# Communication#* create, delete communication connection#* send, receive messages#* transfer status information#* attach or detach remote devices== Processor mode and context switching ==System calls in most Unix-like systems are processed in kernel mode, which is accomplished by changing the processor execution mode to a more privileged one, but no "process" context switch is necessary although a "privilege" context switch does occur.
# Управление процессами#* load#* execute#* end (exit), abort#* создание процесса (codice_7 в Unix-like, codice_11 в Windows_NT Native API)#* get/set process attributes#* wait время, события, signal события#* allocate, free] memory#* create file, delete file#* open, close#* read, write, reposition#* get/set file attributes#* request device, release device#* read, write, reposition#* get/set device attributes#* logically attach or detach devices#* get/set time or date#* get/set system data#* get/set process, file, or device attributes#* create, delete communication connection#* send, receive messages#* transfer status information#* attach or detach remote devicesСистемные вызовы в Unix-подобных системах обрабатываются в режиме ядра, которое завершается повышением режима выполнения процессора в более привилегированный, но изменение контекста процесса не требуется - однако при этом происходит изменение контекста привилегии.