In computing, booting is starting up a computer or computer appliance until it can be used. It can be initiated by hardware such as a button press or by software command. After the power is switched on, the computer is relatively dumb and can read only part of its storage called read-only memory (ROM). There, a small program is stored called firmware. It does power-on self-tests and, most importantly, allows accessing other types of memory like a hard disk and main memory. The firmware loads bigger programs into the computer's main memory and runs it. In general purpose computers, but additionally in smartphones and tablets, optionally a boot manager is run. The boot manager lets a user choose which operating system to run and set more complex parameters for it. The firmware or the boot manager then loads the boot loader into the memory and runs it. This piece of software is able to place an operating system kernel like Windows or Linux into the computer's main memory and run it. Afterwards, the kernel runs so-called user space software – well known is the graphical user interface (GUI), which lets the user log in to the computer or run some other applications. The whole process may take seconds to tenths of seconds on modern day general purpose computers.
The C programming language provides many standard library functions for file input and output. These functions make up the bulk of the C standard library header <stdio.h>. The functionality descends from a "portable I/O package" written by Mike Lesk at Bell Labs in the early 1970s, and officially became part of the Unix operating system in Version 7.
NTLDR is the boot loader for all releases of Windows NT operating system up to and including Windows XP and Windows Server 2003. NTLDR is typically run from the primary hard disk drive, but it can also run from portable storage devices such as a CD-ROM, USB flash drive, or floppy disk. NTLDR can also load a non NT-based operating system given the appropriate boot sector in a file.
Memory-mapped I/O (MMIO) and port-mapped I/O (PMIO) are two complementary methods of performing input/output (I/O) between the central processing unit (CPU) and peripheral devices in a computer. An alternative approach is using dedicated I/O processors, commonly known as channels on mainframe computers, which execute their own instructions.
A chroot on Unix operating systems is an operation that changes the apparent root directory for the current running process and its children. A program that is run in such a modified environment cannot name files outside the designated directory tree. The term "chroot" may refer to the chroot(2) system call or the chroot(8) wrapper program. The modified environment is called a chroot jail.
The configuration file XF86Config of the XFree86 project is used by the X server to set necessary configuration parameters.
Fontconfig is a free software program library designed to provide configuration, enumeration and substitution of fonts to other programs. Fontconfig was originally written and maintained by Keith Packard, and is currently maintained by Behdad Esfahbod.
Xsun is an X Window System (X11) display server implementation included with Solaris, developed by Sun Microsystems. It replaced the older Xnews server, which supported the display of not only X11 applications, but also NeWS and SunView programs. Xsun discontinued support for these legacy environments, and added support for Display PostScript.
Xvfb or X virtual framebuffer is a display server implementing the X11 display server protocol. In contrast to other display servers, Xvfb performs all graphical operations in virtual memory without showing any screen output. From the point of view of the client, it acts exactly like any other X display server, serving requests and sending events and errors as appropriate. However, no output is shown. This virtual server does not require the computer it is running on to have any kind of graphics adapter, a screen or any input device. Only a network layer is necessary.
A substitute character (␚) is a control character that is used in the place of a character that is recognized to be invalid or erroneous, or that cannot be represented on a given device. It is also used as an escape sequence in some programming languages.
evdev is a generic input event interface in the Linux kernel. It generalizes raw input events from device drivers and makes them available through character devices in the /dev/input/ directory.
Linux color management has the same goal as the color management systems (CMS) for other operating systems: to achieve the best possible color reproduction throughout an imaging workflow from its source, through imaging software, and finally onto an output medium. In particular, color management attempts to enable color consistency across media and throughout a color-managed workflow.
Linux startup process is the multi-stage initialization process performed during booting a Linux installation. It is in many ways similar to the BSD and other Unix-style boot processes, from which it derives.
Unicode input is the insertion of a specific Unicode character on a computer by a user; it is a common way to input characters not directly supported by a physical keyboard. Unicode characters can be produced either by selecting them from a display or by typing a certain sequence of keys on a physical keyboard. In addition, a character produced by one of these methods in one web page or document can be copied into another. Unicode is similar to ASCII but provides many more options and encodes many more signs.
In computing, input/output or I/O is the communication between an information processing system, such as a computer, and the outside world, possibly a human or another information processing system. Inputs are the signals or data received by the system and outputs are the signals or data sent from it. The term can also be used as part of an action; to "perform I/O" is to perform an input or output operation.
Wayland is a computer protocol that specifies the communication between a display server and its clients, as well as a reference implementation of the protocol in the C programming language. A display server using the Wayland protocol is called a Wayland compositor.
Kudzu is a hardware probing program which relies on a library of hardware device information. When the computer boots, kudzu detects changes in the running system's hardware configuration, if any, and activates the newly detected hardware. kudzu only runs at boot time, and then exits. There is no performance penalty during normal operation. kudzu detects and configures new and/or changed hardware on a system. When started, kudzu detects the current hardware, and checks it against a database stored in /etc/sysconfig/hwconf, if one exists. It then determines if any hardware has been added or removed from the system. If so, it gives the users the opportunity to configure any added hardware, and unconfigure any removed hardware. It then updates the database in /etc/sysconfig/hwconf. If no previous database exists, kudzu attempts to determine what devices have already been configured, by looking at /etc/modprobe.conf, /etc/sysconfig/network-scripts/, and /etc/X11/xorg.conf.
luit is a utility program used to translate the character set of a computer program so that its output can be displayed correctly on a terminal emulator that uses a different character set. Whereas iconv converts the character set of strings or text files at rest, luit converts the input and output of programs running interactively.
A modeline is a configuration line in xorg.conf or the XFree86 configuration file (XF86Config) that provides information to the display server about a connected computer monitor or television and how to drive it at a specified display resolution. The Modeline is based on the Generalized Timing Formula or the Coordinated Video Timings standards produced by VESA.
