A child process in computing is a process created by another process (the parent process

Parent process

In computing, a parent process is a process that has created one or more child processes.- Unix :In the operating system Unix, every process except is created when another process executes the fork system call. The process that invoked fork is the parent process and the newly-created process is...

).

A child process inherits most of its attribute

Attribute (computing)

In computing, an attribute is a specification that defines a property of an object, element, or file. It may also refer to or set the specific value for a given instance of such....

s, such as open file

Computer file

A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...

s, from its parent. In UNIX

Unix

Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...

, a child process is in fact created (using fork

Fork (operating system)

In computing, when a process forks, it creates a copy of itself. More generally, a fork in a multithreading environment means that a thread of execution is duplicated, creating a child thread from the parent thread....

) as a copy of the parent. The child process can then overlay

Overlay (operating system)

In operating systems, an overlay is when a process replaces itself with the code of another program. On Unix-like systems, this is accomplished with the exec system call....

 itself with a different program (using exec

Exec (operating system)

The exec collection of functions of Unix-like operating systems cause the running process to be completely replaced by the program passed as an argument to the function...

) as required.

Each process may create many child processes but will have at most one parent process; if a process does not have a parent this usually indicates that it was created directly by the kernel. In some systems, including UNIX

Unix

Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...

 based systems such as Linux

Linux

Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

, the very first process (called init

Init

init is a program for Unix-based computer operating systems that spawns all other processes. It runs as a daemon and typically has PID 1. The boot loader starts the kernel and the kernel starts init...

) is started by the kernel at booting

Booting

In computing, booting is a process that begins when a user turns on a computer system and prepares the computer to perform its normal operations. On modern computers, this typically involves loading and starting an operating system. The boot sequence is the initial set of operations that the...

 time and never terminates (see Linux startup process

Linux startup process

The Linux startup process is the process of Linux-operating system initialization. It is in many ways similar to the BSD and other Unix style boot processes, from which it derives.-Overview of typical process:...

); other parentless processes may be launched to carry out various daemon

Daemon (computing)

In Unix and other multitasking computer operating systems, a daemon is a computer program that runs as a background process, rather than being under the direct control of an interactive user...

 tasks in userspace. Another way for a process to end up without a parent is if its parent dies, leaving an orphan process

Orphan process

An orphan process is a computer process whose parent process has finished or terminated, though itself remains running.In a Unix-like operating system any orphaned process will be immediately adopted by the special init system process. This operation is called re-parenting and occurs automatically...

; but in this case it will shortly be adopted by init.

See also

• Exec
  Exec (operating system)
  The exec collection of functions of Unix-like operating systems cause the running process to be completely replaced by the program passed as an argument to the function...
  
  
• Exit
  Exit (operating system)
  On many computer operating systems, a computer process terminates its execution by making an exit system call. More generally, an exit in a multithreading environment means that a thread of execution has stopped running. The operating system reclaims resources that were used by the process...
  
  
• Fork
  Fork (operating system)
  In computing, when a process forks, it creates a copy of itself. More generally, a fork in a multithreading environment means that a thread of execution is duplicated, creating a child thread from the parent thread....
  
  
• Overlay
  Overlay (operating system)
  In operating systems, an overlay is when a process replaces itself with the code of another program. On Unix-like systems, this is accomplished with the exec system call....
  
  
• Parent process
  Parent process
  In computing, a parent process is a process that has created one or more child processes.- Unix :In the operating system Unix, every process except is created when another process executes the fork system call. The process that invoked fork is the parent process and the newly-created process is...
  
  
• pstree, for UNIX to find the child process (pstree PID, where PID is the process id of the process).