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420 lines
6.7 KiB
ReStructuredText
420 lines
6.7 KiB
ReStructuredText
.. COMMENT: COPYRIGHT (c) 1988-2002.
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.. COMMENT: On-Line Applications Research Corporation (OAR).
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.. COMMENT: All rights reserved.
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Process Creation and Execution Manager
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######################################
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Introduction
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============
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The process creation and execution manager provides the functionality
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associated with the creation and termination of processes.
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The directives provided by the process creation and execution manager are:
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- fork_ - Create a Process
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- execl_ - Execute a File
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- execv_ - Execute a File
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- execle_ - Execute a File
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- execve_ - Execute a File
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- execlp_ - Execute a File
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- execvp_ - Execute a File
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- pthread_atfork_ - Register Fork Handlers
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- wait_ - Wait for Process Termination
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- waitpid_ - Wait for Process Termination
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- `_exit`_ - Terminate a Process
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Background
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==========
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POSIX process functionality can not be completely supported by RTEMS. This is
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because RTEMS provides no memory protection and implements a *single process,
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multi-threaded execution model*. In this light, RTEMS provides none of the
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routines that are associated with the creation of new processes. However,
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since the entire RTEMS application (e.g. executable) is logically a single
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POSIX process, RTEMS is able to provide implementations of many operations on
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processes. The rule of thumb is that those routines provide a meaningful
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result. For example, ``getpid()`` returns the node number.
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Operations
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==========
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The only functionality method defined by this manager which is supported by
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RTEMS is the ``_exit`` service. The implementation of ``_exit`` shuts the
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application down and is equivalent to invoking either ``exit`` or
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``rtems_shutdown_executive``.
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Directives
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==========
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This section details the process creation and execution manager's directives.
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A subsection is dedicated to each of this manager's directives and describes
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the calling sequence, related constants, usage, and status codes.
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.. _fork:
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fork - Create a Process
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-----------------------
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.. index:: fork
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.. index:: create a process
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**CALLING SEQUENCE:**
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.. code-block:: c
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#include <sys/types.h>
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int fork( void );
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**STATUS CODES:**
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.. list-table::
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:class: rtems-table
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* - ``ENOSYS``
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- This routine is not supported by RTEMS.
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**DESCRIPTION:**
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This routine is not supported by RTEMS.
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**NOTES:**
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NONE
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.. _execl:
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execl - Execute a File
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----------------------
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.. index:: execl
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.. index:: execute a file
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**CALLING SEQUENCE:**
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.. code-block:: c
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int execl(
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const char *path,
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const char *arg,
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...
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);
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**STATUS CODES:**
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.. list-table::
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:class: rtems-table
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* - ``ENOSYS``
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- This routine is not supported by RTEMS.
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**DESCRIPTION:**
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This routine is not supported by RTEMS.
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**NOTES:**
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NONE
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.. _execv:
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execv - Execute a File
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----------------------
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.. index:: execv
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.. index:: execute a file
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**CALLING SEQUENCE:**
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.. code-block:: c
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int execv(
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const char *path,
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char const *argv[],
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...
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);
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**STATUS CODES:**
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.. list-table::
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:class: rtems-table
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* - ``ENOSYS``
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- This routine is not supported by RTEMS.
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**DESCRIPTION:**
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This routine is not supported by RTEMS.
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**NOTES:**
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NONE
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.. _execle:
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execle - Execute a File
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-----------------------
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.. index:: execle
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.. index:: execute a file
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**CALLING SEQUENCE:**
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.. code-block:: c
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int execle(
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const char *path,
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const char *arg,
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...
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);
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**STATUS CODES:**
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.. list-table::
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:class: rtems-table
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* - ``ENOSYS``
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- This routine is not supported by RTEMS.
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**DESCRIPTION:**
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This routine is not supported by RTEMS.
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**NOTES:**
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NONE
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.. _execve:
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execve - Execute a File
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-----------------------
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.. index:: execve
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.. index:: execute a file
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**CALLING SEQUENCE:**
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.. code-block:: c
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int execve(
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const char *path,
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char *const argv[],
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char *const envp[]
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);
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**STATUS CODES:**
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.. list-table::
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:class: rtems-table
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* - ``ENOSYS``
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- This routine is not supported by RTEMS.
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**DESCRIPTION:**
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This routine is not supported by RTEMS.
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**NOTES:**
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NONE
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.. _execlp:
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execlp - Execute a File
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-----------------------
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.. index:: execlp
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.. index:: execute a file
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**CALLING SEQUENCE:**
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.. code-block:: c
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int execlp(
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const char *file,
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const char *arg,
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...
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);
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**STATUS CODES:**
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.. list-table::
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:class: rtems-table
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* - ``ENOSYS``
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- This routine is not supported by RTEMS.
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**DESCRIPTION:**
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This routine is not supported by RTEMS.
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**NOTES:**
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NONE
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.. _execvp:
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execvp - Execute a File
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-----------------------
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.. index:: execvp
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.. index:: execute a file
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**CALLING SEQUENCE:**
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.. code-block:: c
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int execvp(
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const char *file,
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char *const argv[],
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...
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);
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**STATUS CODES:**
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.. list-table::
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:class: rtems-table
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* - ``ENOSYS``
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- This routine is not supported by RTEMS.
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**DESCRIPTION:**
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This routine is not supported by RTEMS.
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**NOTES:**
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NONE
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.. _pthread_atfork:
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pthread_atfork - Register Fork Handlers
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---------------------------------------
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.. index:: pthread_atfork
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.. index:: register fork handlers
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**CALLING SEQUENCE:**
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.. code-block:: c
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#include <sys/types.h>
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int pthread_atfork(
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void (*prepare)(void),
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void (*parent)(void),
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void (*child)(void)
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);
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**STATUS CODES:**
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.. list-table::
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:class: rtems-table
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* - ``ENOSYS``
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- This routine is not supported by RTEMS.
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**DESCRIPTION:**
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This routine is not supported by RTEMS.
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**NOTES:**
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NONE
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.. _wait:
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wait - Wait for Process Termination
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-----------------------------------
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.. index:: wait
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.. index:: wait for process termination
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**CALLING SEQUENCE:**
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.. code-block:: c
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#include <sys/types.h>
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#include <sys/wait.h>
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int wait(
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int *stat_loc
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);
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**STATUS CODES:**
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.. list-table::
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:class: rtems-table
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* - ``ENOSYS``
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- This routine is not supported by RTEMS.
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**DESCRIPTION:**
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This routine is not supported by RTEMS.
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**NOTES:**
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NONE
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.. _waitpid:
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waitpid - Wait for Process Termination
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--------------------------------------
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.. index:: waitpid
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.. index:: wait for process termination
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**CALLING SEQUENCE:**
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.. code-block:: c
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int wait(
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pid_t pid,
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int *stat_loc,
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int options
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);
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**STATUS CODES:**
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.. list-table::
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:class: rtems-table
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* - ``ENOSYS``
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- This routine is not supported by RTEMS.
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**DESCRIPTION:**
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This routine is not supported by RTEMS.
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**NOTES:**
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NONE
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.. _\_exit:
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_exit - Terminate a Process
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---------------------------
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.. index:: _exit
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.. index:: terminate a process
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**CALLING SEQUENCE:**
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.. code-block:: c
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void _exit(
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int status
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);
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**STATUS CODES:**
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NONE
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**DESCRIPTION:**
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The ``_exit()`` function terminates the calling process.
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**NOTES:**
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In RTEMS, a process is equivalent to the entire application on a single
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processor. Invoking this service terminates the application.
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