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   posix_spawn_file_actions_adddup2.3p    ( 3 )

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Пролог (Prolog)

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.

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Имя (Name)

posix_spawn_file_actions_adddup2 — add dup2 action to spawn file
       actions object (ADVANCED REALTIME)

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Синопсис (Synopsis)

#include <spawn.h>

       int posix_spawn_file_actions_adddup2(posix_spawn_file_actions_t
           *file_actions, int fildes, int newfildes);

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Описание (Description)

The posix_spawn_file_actions_adddup2() function shall add a
       dup2() action to the object referenced by file_actions that shall
       cause the file descriptor fildes to be duplicated as newfildes
       (as if dup2(fildes, newfildes) had been called) when a new
       process is spawned using this file actions object.

       A spawn file actions object is as defined in
       posix_spawn_file_actions_addclose(3p).

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Возвращаемое значение (Return value)

Upon successful completion, the
       posix_spawn_file_actions_adddup2() function shall return zero;
       otherwise, an error number shall be returned to indicate the
       error.

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Ошибки (Error)

The posix_spawn_file_actions_adddup2() function shall fail if:

       EBADF  The value specified by fildes or newfildes is negative or
              greater than or equal to {OPEN_MAX}.

       ENOMEM Insufficient memory exists to add to the spawn file
              actions object.

       The posix_spawn_file_actions_adddup2() function may fail if:

       EINVAL The value specified by file_actions is invalid.

       It shall not be considered an error for the fildes argument
       passed to the posix_spawn_file_actions_adddup2() function to
       specify a file descriptor for which the specified operation could
       not be performed at the time of the call. Any such error will be
       detected when the associated file actions object is later used
       during a posix_spawn() or posix_spawnp() operation.

       The following sections are informative.

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Примеры (Examples)

None.

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Использование в приложениях (Application usage)

The posix_spawn_file_actions_adddup2() function is part of the
       Spawn option and need not be provided on all implementations.

       Implementations may use file descriptors that must be inherited
       into child processes for the child process to remain conforming,
       such as for message catalog or tracing purposes. Therefore, an
       application that calls posix_spawn_file_actions_adddup2() with an
       arbitrary integer for newfildes risks non-conforming behavior,
       and this function can only portably be used to overwrite file
       descriptor values that the application has obtained through
       explicit actions, or for the three file descriptors corresponding
       to the standard file streams. In order to avoid a race condition
       of leaking an unintended file descriptor into a child process, an
       application should consider opening all file descriptors with the
       FD_CLOEXEC bit set unless the file descriptor is intended to be
       inherited across exec.

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Обоснование (Rationale)

Refer to the RATIONALE section in
       posix_spawn_file_actions_addclose(3p).

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Будущие направления (Future directions)

None.

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Смотри также (See also)

dup(3p), posix_spawn(3p), posix_spawn_file_actions_addclose(3p),
       posix_spawn_file_actions_destroy(3p)

       The Base Definitions volume of POSIX.1‐2017, spawn.h(0p)

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