Fork vs. Exec — What's the Difference?
By Tayyaba Rehman & Maham Liaqat — Updated on May 20, 2024
Fork creates a new process by duplicating an existing one, while exec replaces the current process with a new program.
Difference Between Fork and Exec
Table of Contents
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Key Differences
Fork is a system call used in operating systems to create a new process. This new process, called a child process, is a duplicate of the current process, known as the parent process. Exec, on the other hand, is a system call that replaces the current process with a new program. When a process calls exec, it completely transforms into the new program, retaining the same PID.
While fork creates a new process, exec doesn't create a new process but transforms the existing one. Fork is useful when a program needs to run concurrent operations, as it creates multiple processes that can execute independently. Exec is crucial when a process needs to switch to a different program entirely, maintaining the existing execution context.
Fork's primary advantage is its ability to create parallelism by spawning new processes that can run independently or interact with each other. In contrast, exec's strength lies in its efficiency in transforming a process to execute a new program without the overhead of creating a new process. This makes exec suitable for scenarios where a process needs to be replaced rather than duplicated.
Fork and exec are often used together in Unix-like operating systems. A common pattern is for a process to fork a child process and then have the child process call exec to run a different program. This sequence enables efficient process management and program execution in multitasking environments.
Comparison Chart
Function
Creates a new child process
Replaces current process with a new program
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Process Identifier
New PID for the child process
Retains the same PID
Execution Context
Inherits parent's context
Replaces the current context
Usage Scenario
Parallel execution
Program replacement
Efficiency
Allows independent process execution
Transforms process without creating a new one
Compare with Definitions
Fork
Unique child PID.
After fork, the child process has a distinct PID.
Exec
Program execution.
After fork, exec is often used to execute a different program in the child process.
Fork
Parent-child relationship.
The child process created by fork can run different tasks from its parent.
Exec
Replace process image.
The script uses exec to run the new program directly.
Fork
In cutlery or kitchenware, a fork (from Latin: furca 'pitchfork') is a utensil, now usually made of metal, whose long handle terminates in a head that branches into several narrow and often slightly curved tines with which one can spear foods either to hold them to cut with a knife or to lift them to the mouth.
Exec
Retain PID.
Exec keeps the same process identifier after transformation.
Fork
A utensil with two or more prongs, used for eating or serving food.
Exec
Transform current process.
Exec changes the current process into the specified program.
Fork
An implement with two or more prongs used for raising, carrying, piercing, or digging.
Exec
Efficient context switch.
Using exec, the process efficiently switches to the new program without additional overhead.
Fork
A bifurcation or separation into two or more branches or parts.
Exec
An executive.
Fork
The point at which such a bifurcation or separation occurs
A fork in a road.
Exec
The executive officer of a unit of the armed forces.
Fork
One of the branches of such a bifurcation or separation
The right fork.
Exec
(informal) executive, executive officer
Fork
(Games) An attack by one chess piece on two pieces at the same time.
Exec
To execute; to run.
Fork
To raise, carry, pitch, or pierce with a fork.
Exec
The chief executive department of the United States government
Fork
To give the shape of a fork to (one's fingers, for example).
Fork
(Games) To launch an attack on (two chess pieces).
Fork
(Informal) To pay. Used with over, out, or up
Forked over $80 for front-row seats.
Forked up the money owed.
Fork
To divide into two or more branches
The river forks here.
Fork
To use a fork, as in working.
Fork
To turn at or travel along a fork.
Fork
Any of several types of pronged (tined) tools (physical tools), as follows:
Fork
A utensil with spikes used to put solid food into the mouth, or to hold food down while cutting.
Fork
Any of several types of pronged tools for use on farms, in fields, or in the garden or lawn, such as a smaller hand fork for weeding or a larger one for turning over the soil.
Fork
A tuning fork.
Fork
(by abstraction, from the tool shape) A fork in the road, as follows:
Fork
(physical) An intersection in a road or path where one road is split into two.
Fork
(figurative) A fork.
Fork
(by abstraction, from the tool shape) A point where a waterway, such as a river or other stream, splits and flows into two (or more) different directions.
Fork
One of the parts into which anything is furcated or divided; a prong; a branch of a stream, a road, etc.; a barbed point, as of an arrow.
A thunderbolt with three forks
This fork of the river dries up during droughts
Fork
A point in time where one has to make a decision between two life paths.
Fork
(metonymically) Either of the (figurative) paths thus taken.
Fork
Process (software development, content management, data management) A departure from having a single source of truth (SSOT), sometimes intentionally but usually unintentionally.
Fork
(metonymically) Any of the pieces/versions (of software, content, or data sets) thus created.
Single source of truth, SSOT
Fork
(software) The launch of one or more separate software development efforts based upon a modified copy of an existing project, especially in free and open-source software.
Fork
The splitting of the coverage of a topic (within a corpus of content) into two or more pieces.
A content fork may be intentional (as from a schism about goals) or unintentional (merely from a lack of reorganizing, so far).
Fork
(cryptocurrency) A split in a blockchain resulting from protocol disagreements, or a branch of the blockchain resulting from such a split.
Fork
(chess) The simultaneous attack of two adversary pieces with one single attacking piece (especially a knight).
Fork
The crotch. en
Fork
(colloquial) A forklift.
Are you qualified to drive a fork?
Fork
Either of the blades of a forklift (or, in plural, the set of blades), on which the goods to be raised are loaded.
Get those forks tilted back more or you're gonna lose that pallet!
Fork
In a bicycle or motorcycle, the portion of the frameset holding the front wheel, allowing the rider to steer and balance, also called front fork.
The fork can be equipped with a suspension on mountain bikes.
Fork
Horse tack The upper front brow of a saddle bow, connected in the tree by the two saddle bars to the cantle on the other end.
Fork
(obsolete) A gallows.
Fork
(mining) The bottom of a sump into which the water of a mine drains.
Fork
(ambitransitive) To divide into two or more branches or copies.
A road, a tree, or a stream forks.
Fork
To spawn a new child process by duplicating the existing process.
Fork
To launch a separate software development effort based upon a modified copy of an existing software project, especially in free and open-source software.
Fork
To create a copy of a distributed version control repository.
Fork
(transitive) To move with a fork (as hay or food).
Fork
To kick someone in the crotch.
Fork
(intransitive) To shoot into blades, as corn does.
Fork
(transitive) fuck
Fork
To bale a shaft dry.
Fork
An instrument consisting of a handle with a shank terminating in two or more prongs or tines, which are usually of metal, parallel and slightly curved; - used for piercing, holding, taking up, or pitching anything.
Fork
Anything furcate or like a fork in shape, or furcate at the extremity; as, a tuning fork.
Fork
One of the parts into which anything is furcated or divided; a prong; a branch of a stream, a road, etc.; a barbed point, as of an arrow.
Let it fall . . . though the fork invadeThe region of my heart.
A thunderbolt with three forks.
Fork
The place where a division or a union occurs; the angle or opening between two branches or limbs; as, the fork of a river, a tree, or a road.
Fork
The gibbet.
Fork
To shoot into blades, as corn.
The corn beginneth to fork.
Fork
To divide into two or more branches; as, a road, a tree, or a stream forks.
Fork
To raise, or pitch with a fork, as hay; to dig or turn over with a fork, as the soil.
Forking the sheaves on the high-laden cart.
Fork
Cutlery used for serving and eating food
Fork
The act of branching out or dividing into branches
Fork
A part of a forked or branching shape;
He broke off one of the branches
They took the south fork
Fork
An agricultural tool used for lifting or digging; has a handle and metal prongs
Fork
The angle formed by the inner sides of the legs where they join the human trunk
Fork
Lift with a pitchfork;
Pitchfork hay
Fork
Place under attack with one's own pieces, of two enemy pieces
Fork
Divide into two or more branches so as to form a fork;
The road forks
Fork
Shape like a fork;
She forked her fingers
Fork
Create a duplicate process.
The server forks a new process for each client request.
Fork
Inherit parent process space.
Forked processes share the same code but run independently.
Fork
Foundation for multitasking.
Fork enables concurrent operations in the operating system.
Common Curiosities
What is fork in computing?
Fork is a system call that creates a new process by duplicating the existing one.
What does exec do in an operating system?
Exec is a system call that replaces the current process with a new program.
What happens when exec is called?
Exec replaces the current process's memory space with a new program, retaining the same PID.
Is a new process created with exec?
No, exec does not create a new process; it transforms the current process.
Does exec inherit the parent's memory?
No, exec replaces the current process's memory with the new program's memory.
Why is fork important?
Fork allows parallel execution of processes, enabling multitasking in operating systems.
How does fork work?
Fork creates a child process that is a copy of the parent process, but with a unique PID.
Can fork and exec be used together?
Yes, a process often uses fork to create a child process and then exec to run a new program in that child process.
Can exec fail?
Yes, exec can fail if the new program cannot be loaded, often returning an error.
When should fork be used?
Fork should be used when a program needs to perform concurrent tasks.
What is a child process?
A child process is a new process created by fork, which is a copy of the parent process.
How do fork and exec contribute to process management?
Fork and exec together enable efficient creation and execution of new processes, crucial for multitasking in Unix-like operating systems.
What is a PID?
PID stands for Process Identifier, a unique number assigned to each process.
When should exec be used?
Exec should be used when a process needs to run a different program.
What does it mean to inherit process space?
Inheriting process space means the child process starts with the same memory layout as the parent.
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Written by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
Co-written by
Maham Liaqat
