.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Process Creation and Execution Manager
######################################
Introduction
============
The process creation and execution manager provides the functionality
associated with the creation and termination of processes.
The directives provided by the process creation and execution manager are:
- fork_ - Create a Process
- execl_ - Execute a File
- execv_ - Execute a File
- execle_ - Execute a File
- execve_ - Execute a File
- execlp_ - Execute a File
- execvp_ - Execute a File
- pthread_atfork_ - Register Fork Handlers
- wait_ - Wait for Process Termination
- waitpid_ - Wait for Process Termination
- `_exit`_ - Terminate a Process
Background
==========
POSIX process functionality can not be completely supported by RTEMS. This is
because RTEMS provides no memory protection and implements a *single process,
multi-threaded execution model*. In this light, RTEMS provides none of the
routines that are associated with the creation of new processes. However,
since the entire RTEMS application (e.g. executable) is logically a single
POSIX process, RTEMS is able to provide implementations of many operations on
processes. The rule of thumb is that those routines provide a meaningful
result. For example, ``getpid()`` returns the node number.
Operations
==========
The only functionality method defined by this manager which is supported by
RTEMS is the ``_exit`` service. The implementation of ``_exit`` shuts the
application down and is equivalent to invoking either ``exit`` or
``rtems_shutdown_executive``.
Directives
==========
This section details the process creation and execution manager's directives.
A subsection is dedicated to each of this manager's directives and describes
the calling sequence, related constants, usage, and status codes.
.. _fork:
fork - Create a Process
-----------------------
.. index:: fork
.. index:: create a process
**CALLING SEQUENCE:**
.. code-block:: c
#include <sys/types.h>
int fork( void );
**STATUS CODES:**
.. list-table::
:class: rtems-table
* - ``ENOSYS``
- This routine is not supported by RTEMS.
**DESCRIPTION:**
This routine is not supported by RTEMS.
**NOTES:**
NONE
.. _execl:
execl - Execute a File
----------------------
.. index:: execl
.. index:: execute a file
**CALLING SEQUENCE:**
.. code-block:: c
int execl(
const char *path,
const char *arg,
...
);
**STATUS CODES:**
.. list-table::
:class: rtems-table
* - ``ENOSYS``
- This routine is not supported by RTEMS.
**DESCRIPTION:**
This routine is not supported by RTEMS.
**NOTES:**
NONE
.. _execv:
execv - Execute a File
----------------------
.. index:: execv
.. index:: execute a file
**CALLING SEQUENCE:**
.. code-block:: c
int execv(
const char *path,
char const *argv[],
...
);
**STATUS CODES:**
.. list-table::
:class: rtems-table
* - ``ENOSYS``
- This routine is not supported by RTEMS.
**DESCRIPTION:**
This routine is not supported by RTEMS.
**NOTES:**
NONE
.. _execle:
execle - Execute a File
-----------------------
.. index:: execle
.. index:: execute a file
**CALLING SEQUENCE:**
.. code-block:: c
int execle(
const char *path,
const char *arg,
...
);
**STATUS CODES:**
.. list-table::
:class: rtems-table
* - ``ENOSYS``
- This routine is not supported by RTEMS.
**DESCRIPTION:**
This routine is not supported by RTEMS.
**NOTES:**
NONE
.. _execve:
execve - Execute a File
-----------------------
.. index:: execve
.. index:: execute a file
**CALLING SEQUENCE:**
.. code-block:: c
int execve(
const char *path,
char *const argv[],
char *const envp[]
);
**STATUS CODES:**
.. list-table::
:class: rtems-table
* - ``ENOSYS``
- This routine is not supported by RTEMS.
**DESCRIPTION:**
This routine is not supported by RTEMS.
**NOTES:**
NONE
.. _execlp:
execlp - Execute a File
-----------------------
.. index:: execlp
.. index:: execute a file
**CALLING SEQUENCE:**
.. code-block:: c
int execlp(
const char *file,
const char *arg,
...
);
**STATUS CODES:**
.. list-table::
:class: rtems-table
* - ``ENOSYS``
- This routine is not supported by RTEMS.
**DESCRIPTION:**
This routine is not supported by RTEMS.
**NOTES:**
NONE
.. _execvp:
execvp - Execute a File
-----------------------
.. index:: execvp
.. index:: execute a file
**CALLING SEQUENCE:**
.. code-block:: c
int execvp(
const char *file,
char *const argv[],
...
);
**STATUS CODES:**
.. list-table::
:class: rtems-table
* - ``ENOSYS``
- This routine is not supported by RTEMS.
**DESCRIPTION:**
This routine is not supported by RTEMS.
**NOTES:**
NONE
.. _pthread_atfork:
pthread_atfork - Register Fork Handlers
---------------------------------------
.. index:: pthread_atfork
.. index:: register fork handlers
**CALLING SEQUENCE:**
.. code-block:: c
#include <sys/types.h>
int pthread_atfork(
void (*prepare)(void),
void (*parent)(void),
void (*child)(void)
);
**STATUS CODES:**
.. list-table::
:class: rtems-table
* - ``ENOSYS``
- This routine is not supported by RTEMS.
**DESCRIPTION:**
This routine is not supported by RTEMS.
**NOTES:**
NONE
.. _wait:
wait - Wait for Process Termination
-----------------------------------
.. index:: wait
.. index:: wait for process termination
**CALLING SEQUENCE:**
.. code-block:: c
#include <sys/types.h>
#include <sys/wait.h>
int wait(
int *stat_loc
);
**STATUS CODES:**
.. list-table::
:class: rtems-table
* - ``ENOSYS``
- This routine is not supported by RTEMS.
**DESCRIPTION:**
This routine is not supported by RTEMS.
**NOTES:**
NONE
.. _waitpid:
waitpid - Wait for Process Termination
--------------------------------------
.. index:: waitpid
.. index:: wait for process termination
**CALLING SEQUENCE:**
.. code-block:: c
int wait(
pid_t pid,
int *stat_loc,
int options
);
**STATUS CODES:**
.. list-table::
:class: rtems-table
* - ``ENOSYS``
- This routine is not supported by RTEMS.
**DESCRIPTION:**
This routine is not supported by RTEMS.
**NOTES:**
NONE
.. _\_exit:
_exit - Terminate a Process
---------------------------
.. index:: _exit
.. index:: terminate a process
**CALLING SEQUENCE:**
.. code-block:: c
void _exit(
int status
);
**STATUS CODES:**
NONE
**DESCRIPTION:**
The ``_exit()`` function terminates the calling process.
**NOTES:**
In RTEMS, a process is equivalent to the entire application on a single
processor. Invoking this service terminates the application.
