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fork() is the name of the system call that the parent process uses to "divide" itself ("fork") into two identical processes. After calling fork(), the created child process is an exact copy of the parent except for the return value of the fork() call. This includes open files, register state, and all memory allocations, which includes the ...
A child process in computing is a process created by another process (the parent process).This technique pertains to multitasking operating systems, and is sometimes called a subprocess or traditionally a subtask.
Standard names of such functions in C are execl, execle, execlp, execv, execve, and execvp (see below), but not "exec" itself. The Linux kernel has one corresponding system call named "execve", whereas all aforementioned functions are user-space wrappers around it.
Fork and its variants are typically the only way of doing so in Unix-like systems. For a process to start the execution of a different program, it first forks to create a copy of itself. Then, the copy, called the " child process ", calls the exec system call to overlay itself with the other program: it ceases execution of its former program in ...
Copy-on-write (COW), also called implicit sharing [1] or shadowing, [2] is a resource-management technique [3] used in programming to manage shared data efficiently. Instead of copying data right away when multiple programs use it, the same data is shared between programs until one tries to modify it.
All this behavior was packaged as the function pexec, which is the ancestor of execvp, to allow any program to invoke commands in the same way as the shell. The $ character, used previously for identifying arguments to a shell script , became the marker for dereferencing a variable, and could be used to insert a variable's value into a string ...
David A. Wheeler notes [9] four possible outcomes of a fork, with examples: The death of the fork. This is by far the most common case. It is easy to declare a fork, but considerable effort to continue independent development and support. A re-merging of the fork (e.g., egcs becoming "blessed" as the new version of GNU Compiler Collection.)
In the C and C++ programming languages, unistd.h is the name of the header file that provides access to the POSIX operating system API. [1] It is defined by the POSIX.1 standard, the base of the Single Unix Specification, and should therefore be available in any POSIX-compliant operating system and compiler.