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Operating System Articles
Page 69 of 171
How to create a process in Linux?
A process is a program loaded into memory and currently executing. In simple terms, a process is a program in execution state that the operating system manages and schedules for CPU time. Creating Processes with fork() System Call In Linux, a new process is created using the fork() system call. This system call creates a new process by making an exact copy of the calling process's address space. The original process becomes the parent process, while the newly created process becomes the child process. When fork() is called, both parent and child processes continue execution from the ...
Read MoreBig Endian and Little Endian
Big Endian and Little Endian are two different ways that computer systems store multi-byte values in memory. The terms refer to which byte (most significant or least significant) is stored first in a sequence of memory addresses. Byte Order Storage Methods Little Endian − The least significant byte (low-order byte) is stored at the starting address (A), and the most significant byte (high-order byte) is stored at the next address (A + 1). Big Endian − The most significant byte (high-order byte) is stored at the starting address (A), and the least significant byte (low-order byte) is ...
Read MoreInit process on UNIX and Linux systems
The Init process is the parent of all processes in UNIX and Linux systems, executed by the kernel during system boot. Its primary role is to create processes from configuration stored in /etc/inittab. Init spawns getty processes on terminal lines for user logins and controls all autonomous system processes required for proper operation. After reading /etc/inittab, init determines how the system should be configured for each runlevel and sets the default runlevel. Init then starts all background processes after establishing the system's operational state. Process Hierarchy Process Tree Structure ...
Read MoreLinux Process Monitoring
In Linux, the top command is a powerful utility used to monitor running processes in real-time. It displays an ordered list of active processes and updates regularly, showing critical system information like CPU usage, memory consumption, swap memory, cache size, buffer size, process IDs (PIDs), users, and commands. This tool is essential for system administrators to identify processes consuming high memory and CPU resources. How Top Command Works The top command provides a dynamic view of the system's running processes. It refreshes every few seconds by default and sorts processes by CPU usage, with the most resource-intensive processes ...
Read MoreWhat's the difference between a context switch, a process switch and a thread switch in Linux?
Context switching is the fundamental mechanism that allows a multitasking operating system to share a single CPU among multiple processes and threads. It involves storing the current execution state so that it can be restored later, enabling seamless resumption from the same point. Types of Context Switches There are three main types of context switches in Linux, each with different overhead costs and complexity levels. Context Switch (General) A context switch is the general term for saving the current execution state (registers, program counter, stack pointer) of a running task and loading the state of another ...
Read MoreWhat is loopback address?
The loopback address is a special IP address range (127.0.0.0 – 127.255.255.255) reserved for internal communication within a single computer system. The most commonly used loopback address is 127.0.0.1, also known as localhost. This address allows processes on the same machine to communicate with each other through the network stack without requiring physical network hardware. How Loopback Addresses Work When a process sends data to a loopback address, the operating system intercepts the packet and routes it back to itself internally. The data never leaves the computer or passes through the Network Interface Card (NIC). Instead, it is ...
Read MoreWhat is PID manager in Linux?
In Linux, when an executable stored on disk is called a program, and a program loaded into memory and running is called a process. A process is given a unique number called process ID (PID) that identifies that process to the system when it is started. If we ever need to kill a process, for example, we can refer to it by its PID. As each PID is unique, there is no ambiguity or risk of accidentally killing the wrong process (unless you enter the wrong PID). The PID manager is a kernel subsystem responsible for allocating, managing, and ...
Read MoreMicrosoft Interface Definition Language
Microsoft Interface Definition Language (MIDL) is a language used to define interfaces between client and server programs in distributed computing environments. MIDL enables developers to create standardized interface definitions that facilitate communication between different software components, whether they are running on the same machine or across a network. Definition The MIDL compiler is included with the Microsoft Platform Software Development Kit (SDK) and allows developers to create Interface Definition Language (IDL) files and Application Configuration Files (ACF) required for: Remote Procedure Call (RPC) interfaces for distributed computing COM/DCOM interfaces for component-based programming Type libraries for OLE ...
Read MoreWhat is the difference between context switching and interrupt handling?
Context switching and interrupt handling are two fundamental mechanisms in operating systems that manage how the CPU processes tasks. While both involve changing the CPU's execution state, they serve different purposes and operate at different levels of the system. Context Switching Context switching is the process of storing the complete state of a currently running process or thread and loading the state of another process to resume its execution. This mechanism enables multitasking by allowing a single CPU to be shared among multiple processes. During a context switch, the operating system saves the current process's state including ...
Read MoreAdvanced local procedure call (ALPC)
Advanced Local Procedure Call (ALPC) is a high-performance message-passing mechanism in Windows that enables efficient inter-process communication (IPC) between client and server processes. ALPC replaced the older Local Procedure Call (LPC) mechanism and provides optimized communication channels with multiple message-passing techniques based on data size requirements. How ALPC Works The ALPC mechanism follows a client-server communication model. The server process publishes a globally visible connection-port object that clients can access to request services. When a client needs services from a subsystem, it opens a handle to the server's connection-port and sends a connection request. ...
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