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Nice (Unix)
nice is a program found on Unix and Unix-like operating systems such as Linux. It directly maps to a kernel call of the same name. nice is used to invoke a utility or shell script with a particular CPU priority, thus giving the process more or less CPU time than other processes. A niceness of -20 is the lowest niceness, or highest priority. The default niceness for processes is inherited from its parent process and is usually 0. Systems have diverged on what priority is the lowest. Linux systems document a niceness of 19 as the lowest priority, BSD systems document 20 as the lowest priority. In both cases, the "lowest" priority is documented as running only when nothing else wants to. Etymology ''Niceness value'' is a number attached to processes in *nix systems, that is used along with other data (such as the amount of I/O done by each process) by the kernel process scheduler to calculate a process' 'true priority'which is used to decide how much CPU time is allocated t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bell Labs
Nokia Bell Labs, commonly referred to as ''Bell Labs'', is an American industrial research and development company owned by Finnish technology company Nokia. With headquarters located in Murray Hill, New Jersey, Murray Hill, New Jersey, the company operates several laboratories in the United States and around the world. As a former subsidiary of the American Telephone and Telegraph Company (AT&T), Bell Labs and its researchers have been credited with the development of radio astronomy, the transistor, the laser, the photovoltaic cell, the charge-coupled device (CCD), information theory, the Unix operating system, and the programming languages B (programming language), B, C (programming language), C, C++, S (programming language), S, SNOBOL, AWK, AMPL, and others, throughout the 20th century. Eleven Nobel Prizes and five Turing Awards have been awarded for work completed at Bell Laboratories. Bell Labs had its origin in the complex corporate organization of the Bell System telepho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scheduling (computing)
In computing, scheduling is the action of assigning resources to perform tasks. The resources may be processors, network links or expansion cards. The tasks may be threads, processes or data flows. The scheduling activity is carried out by a mechanism called a scheduler. Schedulers are often designed so as to keep all computer resources busy (as in load balancing), allow multiple users to share system resources effectively, or to achieve a target quality-of-service. Scheduling is fundamental to computation itself, and an intrinsic part of the execution model of a computer system; the concept of scheduling makes it possible to have computer multitasking with a single central processing unit (CPU). Goals A scheduler may aim at one or more goals, for example: * maximizing '' throughput'' (the total amount of work completed per time unit); * minimizing '' wait time'' (time from work becoming ready until the first point it begins execution); * minimizing '' latency'' o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Util-linux
is a package of utilities distributed by the Linux Kernel Organization for use in a Linux operating system. A fork, (with meaning "next generation"), was created when development stalled, but has been renamed back to , and is the official version of the package. Content The package includes the following utilities: Removed content Utilities formerly included, but removed : * arch * chkdupexe * clock * cytune * ddate * elvtune * fastboot * fasthalt * halt * initctl * ramsize * rdev * reboot * rootflags * shutdown Shutdown or shut down may refer to: * Government shutdowns * Shutdown (computing) * Shutdown (economics) * Shutdown (nuclear reactor) Arts and entertainment Music * "Shut Down" (The Beach Boys song), 1963 * '' Shut Down Volume 2'', a 1964 album ... * simpleinit * tailf * vidmode See also * * * * * Notes References External links The util-linux code repository.pub/linux/utils/util-linuxon Kernel.org util-linux development discussion and bug repor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Top (software)
top is a task manager or system monitor program, found in many Unix-like operating systems, that displays information about CPU and memory utilization. Overview The program produces an ordered list of running processes selected by user-specified criteria, and updates it periodically. Default ordering is by CPU usage, and only the top CPU consumers are shown (hence the name). top shows how much processing power and memory are being used, as well as other information about the running processes. Some versions of top allow extensive customization of the display, such as choice of columns or sorting method. top is useful for system administrators, as it shows which users and processes are consuming the most system resources at any given time. Implementations There are several different versions of top. The traditional Unix version was written by William LeFebvre and originally copyrighted in 1984. It is hosted on SourceForge, and release 3.7 was announced in 2008. The Linux vers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ps (Unix)
In most Unix and Unix-like operating systems, the ps (''process status'') program displays the currently-running processes. The related Unix utility top provides a real-time view of the running processes. Implementations KolibriOS includes an implementation of the command. The command has also been ported to the IBM i operating system. In Windows PowerShell, ps is a predefined command alias for the Get-Process cmdlet, which essentially serves the same purpose. Examples # ps PID TTY TIME CMD 7431 pts/0 00:00:00 su 7434 pts/0 00:00:00 bash 18585 pts/0 00:00:00 ps Users can pipeline ps with other commands, such as less to view the process status output one page at a time: $ ps -A , less Users can also utilize the ps command in conjunction with the grep command (see the pgrep and pkill commands) to find information about a single process, such as its id: $ # Trying to find the PID of `firefox-bin` which is 2701 $ ps -A , grep firefox-b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kill (command)
In computing, kill is a command that is used in several popular operating systems to send signals to running processes. Implementations Unix and Unix-like In Unix and Unix-like operating systems, kill is a command used to send a signal to a process. By default, the message sent is the termination signal, which requests that the process exit. But ''kill'' is something of a misnomer; the signal sent may have nothing to do with process killing. The kill command is a wrapper around the kill() system call, which sends signals to processes or process groups on the system, referenced by their numeric process IDs (PIDs) or process group IDs (PGIDs). kill is always provided as a standalone utility as defined by the POSIX standard. However, most shells have built-in kill commands that may slightly differ from it. There are many different signals that can be sent (see ''signal'' for a full list), although the signals in which users are generally most interested are SIGTERM (" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berkeley Software Distribution
The Berkeley Software Distribution (BSD), also known as Berkeley Unix or BSD Unix, is a discontinued Unix operating system developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Berkeley, beginning in 1978. It began as an improved derivative of AT&T's original Unix that was developed at Bell Labs, based on the source code but over time diverging into its own code. BSD would become a pioneer in the advancement of Unix and computing. BSD's development was begun initially by Bill Joy, who added virtual memory capability to Unix running on a VAX-11 computer. In the 1980s, BSD was widely adopted by workstation vendors in the form of proprietary Unix distributions such as DEC Ultrix and Sun Microsystems SunOS due to its permissive licensing and familiarity to many technology company founders and engineers. It also became the most popular Unix at universities, where it was used for the study of operating systems. BSD was sponsored ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scheduling (computing)
In computing, scheduling is the action of assigning resources to perform tasks. The resources may be processors, network links or expansion cards. The tasks may be threads, processes or data flows. The scheduling activity is carried out by a mechanism called a scheduler. Schedulers are often designed so as to keep all computer resources busy (as in load balancing), allow multiple users to share system resources effectively, or to achieve a target quality-of-service. Scheduling is fundamental to computation itself, and an intrinsic part of the execution model of a computer system; the concept of scheduling makes it possible to have computer multitasking with a single central processing unit (CPU). Goals A scheduler may aim at one or more goals, for example: * maximizing '' throughput'' (the total amount of work completed per time unit); * minimizing '' wait time'' (time from work becoming ready until the first point it begins execution); * minimizing '' latency'' o ... [...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 .e., uid=0 regardless of the name of that account; and in systems which implement a r 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) in all mod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Processing Unit
A central processing unit (CPU), also called a central processor, main processor, or just processor, is the primary Processor (computing), processor in a given computer. Its electronic circuitry executes Instruction (computing), instructions of a computer program, such as arithmetic, logic, controlling, and input/output (I/O) operations. This role contrasts with that of external components, such as main memory and I/O circuitry, and specialized coprocessors such as graphics processing units (GPUs). The form, CPU design, design, and implementation of CPUs have changed over time, but their fundamental operation remains almost unchanged. Principal components of a CPU include the arithmetic–logic unit (ALU) that performs arithmetic operation, arithmetic and Bitwise operation, logic operations, processor registers that supply operands to the ALU and store the results of ALU operations, and a control unit that orchestrates the #Fetch, fetching (from memory), #Decode, decoding and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Input/output
In computing, input/output (I/O, i/o, or informally io or IO) is the communication between an information processing system, such as a computer, and the outside world, such as another computer system, peripherals, or a human operator. 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. are the pieces of hardware used by a human (or other system) to communicate with a computer. For instance, a keyboard or computer mouse is an input device for a computer, while monitors and printers are output devices. Devices for communication between computers, such as modems and network cards, typically perform both input and output operations. Any interaction with the system by an interactor is an input and the reaction the system responds is called the output. The designation of a device as either input or output depend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Process (computing)
In computing, a process is the Instance (computer science), instance of a computer program that is being executed by one or many thread (computing), threads. There are many different process models, some of which are light weight, but almost all processes (even entire virtual machines) are rooted in an operating system (OS) process which comprises the program code, assigned system resources, physical and logical access permissions, and data structures to initiate, control and coordinate execution activity. Depending on the OS, a process may be made up of multiple threads of execution that execute instructions Concurrency (computer science), concurrently. While a computer program is a passive collection of Instruction set, instructions typically stored in a file on disk, a process is the execution of those instructions after being loaded from the disk into memory. Several processes may be associated with the same program; for example, opening up several instances of the same progra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
