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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, exec built-in command replaces the shell process with the specified program.〔(''exec'' built-in command in bash manual ). Gnu.org. Retrieved on 2013-01-01.〕 Though, in some languages the call named exec means passing the command line to a command interpreter, a different function. ==Nomenclature== Interfaces to ''exec'' and its implementations vary. Depending on programming language it may be accessible via one or more functions, and depending on operating system it may be represented with one or more actual system calls. For this reason ''exec'' is sometimes described as a ''collection of functions''. Standard names of such functions in C are execl, execle, execlp, execv, execve, and execvp (see below), but not "exec" itself. Linux kernel has one corresponding system call named "execve", whereas all aforementioned functions are user-space wrappers around it. Higher-level languages usually provide one call named exec. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Exec (computing)」の詳細全文を読む スポンサード リンク
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