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EXEC(1P)                POSIX Programmer's Manual               EXEC(1P)

ПРОЛОГ

       This manual page is part of the POSIX Programmer's Manual.  The
       Linux implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior),
       or the interface may not be implemented on Linux.

ИМЯ

       exec — execute commands and open, close, or copy file descriptors

СИНТАКСИС

       exec [command [argument...]]

ОПИСАНИЕ

       The exec utility shall open, close, and/or copy file descriptors
       as specified by any redirections as part of the command.

       If exec is specified without command or arguments, and any file
       descriptors with numbers greater than 2 are opened with
       associated redirection statements, it is unspecified whether
       those file descriptors remain open when the shell invokes another
       utility.  Scripts concerned that child shells could misuse open
       file descriptors can always close them explicitly, as shown in
       one of the following examples.

       If exec is specified with command, it shall replace the shell
       with command without creating a new process. If arguments are
       specified, they shall be arguments to command.  Redirection
       affects the current shell execution environment.

ПАРАМЕТРЫ

       None.

ОПЕРАНДЫ

       See the DESCRIPTION.

СТАНДАРТНЫЙ ВВОД

       Not used.

ФАЙЛЫ ВВОДА

       None.

ПЕРЕМЕННЫЕ ОКРУЖЕНИЯ

       None.

АСИНХРОННЫЕ СОБЫТИЯ

       Default.

СТАНДАРТНЫЙ ВЫВОД

       Not used.

СТАНДАРТНАЯ ОШИБКА

       The standard error shall be used only for diagnostic messages.

ФАЙЛЫ ВЫВОДА

       None.

РАСШИРЕННОЕ ОПИСАНИЕ

       None.

КОД ВЫХОДА

       If command is specified, exec shall not return to the shell;
       rather, the exit status of the process shall be the exit status
       of the program implementing command, which overlaid the shell. If
       command is not found, the exit status shall be 127. If command is
       found, but it is not an executable utility, the exit status shall
       be 126. If a redirection error occurs (see Section 2.8.1,
       Consequences of Shell Errors), the shell shall exit with a value
       in the range 1-125. Otherwise, exec shall return a zero exit
       status.

ПОСЛЕДСТВИЯ ОШИБОК

       Default.

       The following sections are informative.

ПРИМЕНЕНИЕ

       None.

ПРИМЕРЫ

       Open readfile as file descriptor 3 for reading:

           exec 3< readfile

       Open writefile as file descriptor 4 for writing:

           exec 4> writefile

       Make file descriptor 5 a copy of file descriptor 0:

           exec 5<&0

       Close file descriptor 3:

           exec 3<&-

       Cat the file maggie by replacing the current shell with the cat
       utility:

           exec cat maggie

ОБЪЯСНЕНИЕ

       Most historical implementations were not conformant in that:

           foo=bar exec cmd

       did not pass foo to cmd.

НАПРАВЛЕНИЯ РАЗВИТИЯ

       None.

СМОТРИТЕ ТАКЖЕ

       Section 2.14, Special Built-In Utilities

АВТОРСКИЕ ПРАВА

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any
       discrepancy between this version and the original IEEE and The
       Open Group Standard, the original IEEE and The Open Group
       Standard is the referee document. The original Standard can be
       obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page
       are most likely to have been introduced during the conversion of
       the source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group               2017                          EXEC(1P)

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