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Longman Dictionary of Contemporary English
▪ Giants team execs insist the new ballpark train has picked up too much steam to be stopped by one or two players.
▪ Initiative supporters say fraudulent execs should not be allowed to hide behind a corporate shield.
▪ To help the process, Napster has published the email addresses of key music business execs on its site.
▪ What was I supposed to do, tell the account execs to dump half their clients?

n. (context informal English) executive, executive officer

Exec (system call)

In computing, exec is a functionality of an operating system that runs an executable file in the context of an already existing process, replacing the previous executable. This act is also referred to as an overlay. It is especially important in Unix-like systems, although exists elsewhere. As a new process is not created, the process identifier (PID) does not change, but the machine code, data, heap, and stack of the process are replaced by those of the new program.

The exec is available for many programming languages including compilable languages and some scripting languages. In OS command interpreters, the exec built-in command replaces the shell process with the specified program.


Exec or EXEC may refer to:

  • Executive officer, a person responsible for running an organization
  • Executive producer, provides finance and guidance for the making of a commercial entertainment product
  • A family of kit helicopters produced by RotorWay International
Exec (Amiga)

Exec is the multitasking kernel of AmigaOS. It enabled pre-emptive multitasking in as little as 256  KB of memory (as supplied with the first Amiga 1000s). Exec provided functionality for multitasking, memory allocation, interrupt handling and handling of dynamic shared libraries.

It acts as a scheduler for tasks running on the system, providing pre-emptive multitasking with prioritized round-robin scheduling. Exec also provides access to other libraries and high-level inter-process communication via message passing. Other comparable microkernels have had performance problems because of the need to copy messages between address spaces. Since the Amiga has only one address space, Exec message passing is quite efficient. The only fixed memory address in the Amiga software (address 4) is a pointer to exec.library, which can then be used to access other libraries. Exec was designed and implemented by Carl Sassenrath.

Unlike newer modern operating systems, the exec kernel does not run "privileged". Contemporary operating systems for the 68000 such as Atari TOS and SunOS used trap instructions for invoking kernel functions. This made the kernel functions run in the 68000's supervisor mode, while user software ran in the unprivileged user mode. By contrast, exec function calls are made with the library jump table, and the kernel code normally executes in user mode. Whenever supervisor mode is needed, either by the kernel or user programs, the library functions Supervisor or SuperState are used.

One limitation of the Exec kernel was that an uncooperative program could disable multitasking for a long period (or indefinitely) by invoking Amiga_Exec's Forbid or Disable with no later invocation of corresponding Permit or Enable calls, causing the environment to run as a single task. Multitasking could also be disabled by programs which – by software bug or intent – modify Exec's data structures or the code itself stored in RAM, possible due to lack of MMU support.

Even with such limitations, Exec satisfies the definition of preemptive scheduling algorithm, using a preemptive scheduling routine and basing its interrupt intervals on a clock.

Linux kernel developer Linus Torvalds once described the Amiga design as cooperative even though it uses a preemptive scheduling policy. The reason for that, he argued, was because the lack of [[memory protection|[memory] protection]] between tasks, meant a task could hinder the system from operating preemptively. As tasks would need to choose not to stop the preemptive mechanism this would reduce to a kind of inverted cooperative system. This kind of conflation between protection and scheduler policy is nonstandard.

ExecSG (Second Generation) is the kernel used by AmigaOS 4. This kernel was licensed by Hyperion Entertainment from Thomas Frieden and Hans-Jörg Frieden. It exposes the same functions and structures as the Commodore Amiga Exec kernel but only runs on PowerPC CPUs. The ultimate origin of ExecSG is unspecified.

Exec (errand service)

Exec was a company based in San Francisco, United States, that provided companies and individuals access to on-demand personal assistants (for delivery, furniture assembly, research, etc.) and cleaning services. Started by Justin Kan, founder of, in February 2012 with co-founders Daniel Kan, his brother, and Amir Ghazvinian, Exec was backed by Y Combinator and other prominent investors. The company was acquired by Handy (company) in January 2014.

Usage examples of "exec".

A club for those media execs who were at the second summer of love, a pretty high-class place for those who want to knock back guarana alcopops and go at it like knives.

One of the execs at the media studios had been trying to contract Argent for a shadowrun over the last three weeks.

There were couples meeting up for dates, junior execs in sweatpants hot from the raquets court, and women who had been working late now, with their blouses unfastened a couple of notches, looking for fun.

Conference Final in an astounding four-game sweep, and as Ty held the Prince of Wales trophy high above his head on home ice, he lifted his eyes to the skybox where all the Kidco execs sat watching.

Images cut, shifted, jumped, blurred, and blended across the screen, linking the Hreshi and the Dedelphi while Arron talked about the immeasurable wealth new bioforms could provide in terms of nanotech advances and how corporate execs would go to any lengths to recoup their outlays.

The vandals resembled ad execs, very clean and dapper and well groomed.

Get in there and compete with all the ass kissers and bottom feeders, all the no-talent schmucks that constellate around the studio execs who don’t know what they’re doing either.

And but the ironic third consequence was that almost all the large slick advertising agencies with substantial Network billings among these the Icarian Viney and Veals went down, too, in the Big Four's maelstrom, taking with them countless production companies, graphic artists, account execs, computer-enhancement technicians, ruddy-tongued product-spokespersons, horn-rimmed demographers, etc.

It was one reason he'd even been able to stick out his nine residential months here with twenty-one other newly detoxed housebreakers, hoods, whores, fired execs, Avon ladies, subway musicians, beer-bloated construction workers, vagrants, indignant car salesmen, bulimic trauma-mamas, bunko artists, mincing pillow-biters, North End hard guys, pimply kids with electric noserings, denial-ridden housewives and etc.

There were a lot of people including myself, I might as well say who didn't think the top execs would want to add to those problems by shouting to the world that we'd found an old mine site, probably of great historical interest.

He was one of your junior execs when you were an active corporate raider, wasn't he?

There were couples meeting up for dates, junior execs in sweatpants hot from the raquets court, and women who had been working late now, with their blouses unfastened a couple of notches, looking for fun.