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Launchd
launchd is an init and operating system service management daemon created by Apple Inc. as part of macOS to replace its BSD-style init and SystemStarter. There have been efforts to port launchd to FreeBSD and derived systems. Components There are two main programs in the launchd system: launchd and launchctl. ''launchd'' manages the daemons at both a system and user level. Similar to xinetd, launchd can start daemons on demand. Similar to watchdogd, launchd can monitor daemons to make sure that they keep running. launchd also has replaced init as PID 1 on macOS and as a result it is responsible for starting the system at boot time. Configuration files define the parameters of services run by launchd. Stored in the LaunchAgents and LaunchDaemons subdirectories of the Library folders, the property list-based files have approximately thirty different keys that can be set. launchd itself has no knowledge of these configuration files or any ability to read them - that is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cron
The cron command-line utility is a job scheduler on Unix-like operating systems. Users who set up and maintain software environments use cron to schedule jobs (commands or shell scripts), also known as cron jobs, to run periodically at fixed times, dates, or intervals. It typically automates system maintenance or administration—though its general-purpose nature makes it useful for things like downloading files from the Internet and downloading email at regular intervals. Cron is most suitable for scheduling repetitive tasks. Scheduling one-time tasks can be accomplished using the associated ''at'' utility. Cron's name originates from ''chronos'', the Greek word for time. Overview The actions of cron are driven by a crontab (cron table) file, a configuration file that specifies shell commands to run periodically on a given schedule. The crontab files are stored where the lists of jobs and other instructions to the cron daemon are kept. Users can have their own individual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Booting
In computing, booting is the process of starting a computer as initiated via hardware such as a button or by a software command. After it is switched on, a computer's central processing unit (CPU) has no software in its main memory, so some process must load software into memory before it can be executed. This may be done by hardware or firmware in the CPU, or by a separate processor in the computer system. Restarting a computer also is called rebooting, which can be "hard", e.g. after electrical power to the CPU is switched from off to on, or "soft", where the power is not cut. On some systems, a soft boot may optionally clear RAM to zero. Both hard and soft booting can be initiated by hardware such as a button press or by a software command. Booting is complete when the operative runtime system, typically the operating system and some applications,Including daemons. is attained. The process of returning a computer from a state of sleep (suspension) does not involve bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syntax
In linguistics, syntax () is the study of how words and morphemes combine to form larger units such as phrases and sentences. Central concerns of syntax include word order, grammatical relations, hierarchical sentence structure ( constituency), agreement, the nature of crosslinguistic variation, and the relationship between form and meaning (semantics). There are numerous approaches to syntax that differ in their central assumptions and goals. Etymology The word ''syntax'' comes from Ancient Greek roots: "coordination", which consists of ''syn'', "together", and ''táxis'', "ordering". Topics The field of syntax contains a number of various topics that a syntactic theory is often designed to handle. The relation between the topics is treated differently in different theories, and some of them may not be considered to be distinct but instead to be derived from one another (i.e. word order can be seen as the result of movement rules derived from grammatical relations). Se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boolean Data Type
In computer science, the Boolean (sometimes shortened to Bool) is a data type that has one of two possible values (usually denoted ''true'' and ''false'') which is intended to represent the two truth values of logic and Boolean algebra. It is named after George Boole George Boole (; 2 November 1815 – 8 December 1864) was a largely self-taught English mathematician, philosopher, and logician, most of whose short career was spent as the first professor of mathematics at Queen's College, Cork in ..., who first defined an algebraic system of logic in the mid 19th century. The Boolean data type is primarily associated with Conditional (computer programming), conditional statements, which allow different actions by changing control flow depending on whether a programmer-specified Boolean ''condition'' evaluates to true or false. It is a special case of a more general ''logical data type—''logic does not always need to be Boolean (see probabilistic logic). Generali ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mach (kernel)
Mach () is a kernel developed at Carnegie Mellon University by Richard Rashid and Avie Tevanian to support operating system research, primarily distributed and parallel computing. Mach is often considered one of the earliest examples of a microkernel. However, not all versions of Mach are microkernels. Mach's derivatives are the basis of the operating system kernel in GNU Hurd and of Apple's XNU kernel used in macOS, iOS, iPadOS, tvOS, and watchOS. The project at Carnegie Mellon ran from 1985 to 1994, ending with Mach 3.0, which is a true microkernel. Mach was developed as a replacement for the kernel in the BSD version of Unix, so no new operating system would have to be designed around it. Mach and its derivatives exist within a number of commercial operating systems. These include all using the XNU operating system kernel which incorporates an earlier non-microkernel Mach as a major component. The Mach virtual memory management system was also adopted in 4.4BSD by the BSD de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superuser
In computing, the superuser is a special user account used for system administration. Depending on the operating system (OS), the actual name of this account might be root, administrator, admin or supervisor. In some cases, the actual name of the account is not the determining factor; on Unix-like systems, for example, the user with a user identifier (UID) of zero is the superuser, regardless of the name of that account; and in systems which implement a role based security model, any user with the role of superuser (or its synonyms) can carry out all actions of the superuser account. The principle of least privilege recommends that most users and applications run under an ordinary account to perform their work, as a superuser account is capable of making unrestricted, potentially adverse, system-wide changes. Unix and Unix-like In Unix-like computer OSes (such as Linux), ''root'' is the conventional name of the user who has all rights or permissions (to all files and programs) i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OS X Yosemite
OS X Yosemite ( ; version 10.10) is the eleventh major release of macOS, Apple Inc.'s desktop and server operating system for Macintosh computers. OS X Yosemite was announced and released to developers on June 2, 2014, at WWDC 2014 and released to public beta testers on July 24, 2014. Yosemite was released to consumers on October 16, 2014. Following the Northern California landmark-based naming scheme introduced with OS X Mavericks, Yosemite is named after the national park. System requirements All Macintosh products capable of running OS X Mountain Lion (v10.8.x) are able to run Yosemite as the two operating systems have the same requirements. However, to take full advantage of the Handoff feature, additional minimum system requirements include a Mac with Bluetooth LE (Bluetooth 4.0). As with Mavericks and Mountain Lion, 2GB of RAM, 8GB of available storage, and Mac OS X Snow Leopard 10.6.8 or later are required. These are the models that are compatible with OS X Yosemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OS X Mountain Lion
OS X Mountain Lion (version 10.8) is the ninth major release of macOS, Apple Inc.'s desktop and server operating system for Macintosh computers. OS X Mountain Lion was released on July 25, 2012, for purchase and download through Apple's Mac App Store, as part of a switch to releasing OS X versions online and every year, rather than every two years or so. Named to signify its status as a refinement of the previous OS X version, Lion, Apple's stated aims in developing Mountain Lion were to allow users to more easily manage and synchronise content between multiple Apple devices and to make the operating system more familiar. The operating system gained the new malware-blocking system Gatekeeper and integration with Apple's online Game Center and iCloud services, while the Safari web browser was updated to version 6. As on iOS, Notes and Reminders became full applications, separate from Mail and Calendar, while the iChat application was replaced with a version of iOS's Message ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daring Fireball
John Gruber (born 1973) is a technology blogger, UI designer, and one of the inventors of the Markdown markup language. History Gruber is from Philadelphia, Pennsylvania. He received his Bachelor of Science in computer science from Drexel University, then worked for Bare Bones Software (2000–02) and Joyent (2005–06). In 2004, Aaron Swartz and Gruber worked together to create the Markdown language, with the goal of enabling people "to write using an easy-to-read and easy-to-write plain text format, optionally convert it to structurally valid XHTML (or HTML)".Markdown 1.0.1 readme source code Daring Fireball Since 2002, Gruber has written and produced Daring Fireball, a technology-focused blog. He has described his Daring Fireball writing as a " Mac column in the form of a weblog." It was partly inspired by kottke.org by Jason Kottke. The site is written in the form of a tumblelog called ''The Linked List'', a linklog with brief commentary, in between occasional longfor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loadable Kernel Module
In computing, a loadable kernel module (LKM) is an object file that contains code to extend the running kernel, or so-called ''base kernel'', of an operating system. LKMs are typically used to add support for new hardware (as device drivers) and/or filesystems, or for adding system calls. When the functionality provided by an LKM is no longer required, it can be unloaded in order to free memory and other resources. Most current Unix-like systems and Microsoft Windows support loadable kernel modules under different names, such as kernel loadable module (kld) in FreeBSD, kernel extension (kext) in macOS (although support for third-party modules is being dropped), kernel extension module in AIX, kernel-mode driver in Windows NT and downloadable kernel module (DKM) in VxWorks. They are also known as kernel loadable modules (or KLM), and simply as kernel modules (KMOD). Advantages Without loadable kernel modules, an operating system would have to include all possible anticipated fu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BootX (Apple)
BootX is a software-based bootloader designed and developed by Apple Inc. for use on the company's Macintosh computer range. BootX is used to prepare the computer for use, by loading all required device drivers and then starting-up Mac OS X by booting the kernel on all PowerPC Macintoshes running the Mac OS X 10.2 operating system or later versions. Using BootROM, a read-only memory (ROM) computer chip containing OpenFirmware, a graphical bootsplash is shown briefly on all compatible Macintosh computers as a grey Apple logo with a spinning cursor that appears during the startup sequence. The program is freely available as part of the Darwin operating system under the open-source Apple Public Source License. BootX was superseded by another nearly identical bootloader named boot.efi and an Extensible Firmware Interface ROM on the release of the Intel-based Mac. History Older Macintoshes dating from 1983 until 1998 utilized a basic bootloader; the bootloader was solely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open Firmware
Open Firmware is a standard defining the interfaces of a computer firmware system, formerly endorsed by the Institute of Electrical and Electronics Engineers (IEEE). It originated at Sun Microsystems, where it was known as OpenBoot, and has been used by vendors including Sun, Apple, IBM and ARM. Open Firmware allows the system to load platform-independent drivers directly from a PCI device, improving compatibility. Open Firmware may be accessed through its command line interface, which uses the Forth programming language. Open Firmware is described by IEEE standard ''IEEE 1275-1994'', which was not reaffirmed by the Open Firmware Working Group (OFWG) since 1998 and has therefore been officially withdrawn by IEEE. Several commercial implementations of Open Firmware have been released to the Open Source community in 2006, including Sun OpenBoot, Firmworks OpenFirmware and Codegen SmartFirmware. The source code is available from the OpenBIOS project. Sun's implementation is av ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
