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Documentation: migrate "Running Applications from NSH" from wiki
link: https://cwiki.apache.org/confluence/display/NUTTX/Running+Applications+from+NSH
This commit is contained in:
raiden00pl
Xiang Xiao
@@ -22,3 +22,4 @@ starts a given task instead of the main ``nsh`` application.
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builtin.rst
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installation.rst
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login.rst
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running_apps.rst
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@@ -0,0 +1,180 @@
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=============================
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Running Applications from NSH
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=============================
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This page describes current and planned features for the NuttX NuttShell (NSH).
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Think of this page as a roadmap. Most of the features have been implemented and
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incorporated into NSH; others are just ideas that are being tossed around (noted
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as NOT implemented). The NSH document will be updated as new features are included.
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There are currently be three ways to execute applications from NSH:
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#. Executing Builtin Applications
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**Builtin Applications**
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The current implementation of NSH allows for the execution
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of "named" or "builtin" applications. The applications are simply task entry points
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in the common FLASH image that have names assigned to them. Simply entering that name
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from the NSH command line will cause the associated application to run.
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See the NSH documentation for further details.
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**Example**
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For example:
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.. code-block:: bash
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NuttShell (NSH) NuttX-6.24
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nsh> hello
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Hello, World!!
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nsh>
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**Configuration Settings**
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This functionality depends on these configuration settings:
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* ``CONFIG_BUILTIN=y`` Enables NuttX support for builtin applications, and
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* ``CONFIG_NSH_BUILTIN_APPS=y`` Enables NSH support for builtin applications
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In additional to other configuration needed by NSH.
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#. Executing Application from a File System
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**OS Interfaces**
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NuttX supports running applications that reside on a file system as well.
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The standard interfaces used to do this include:
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* ``execv()``
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* ``execl()``
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* ``posix_spawn()``
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**Configuration Settings**
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Execution of applications on a file system is currently supported by Nuttx.
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This feature is enabled with:
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* ``CONFIG_LIBC_EXECFUNCS=y`` Enable support for ``execv()``, ``execl()``,
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and ``posix_spawn()``, and
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* ``CONFIG_NSH_FILE_APPS=y`` Enable execution of programs in a file system by NSH.
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**Example**
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When this feature is enabled, you will be able to do the following:
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.. code-block:: bash
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NuttShell (NSH) NuttX-6.24
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nsh> mount -t vfat /dev/mmcsd0 /mnt/sdcard
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nsh> ls -l /mnt/sdcard
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/mnt/sdcard:
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-rw-r--r-- 198 hello
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nsh> /mnt/sdcard/hello
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Hello, World!!
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nsh>
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**The PATH Variable**
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Notice that the absolute path to the hello program was used. This can be
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simplified by setting the following in your configuration:
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* ``CONFIG_BINFMT_EXEPATH=y`` Enable use of the path variable to find executable programs.
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**Example**
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Then, the example becomes:
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.. code-block:: bash
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NuttShell (NSH) NuttX-6.24
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nsh> mount -t vfat /dev/mmcsd0 /mnt/sdcard
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nsh> ls -l /mnt/sdcard
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/mnt/sdcard:
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-rw-r--r-- 198 hello
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nsh> set PATH /mnt/sdcard
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nsh> hello
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Hello, World!!
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nsh>
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**Pre-initialized PATH Variables**
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One final simplification: The initial PATH variable can be configured so that
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the PATH to your executable programs is already defined when NSH starts. This
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is down with:
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* ``CONFIG_PATH_INITIAL="/mnt/sdcard"``
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This functionality is already in place.
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#. Executing Builtin Applications from a File System
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**Namespace Management**
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NuttX supports a virtual file system (VFS) that may used to manage namespaces.
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Linux uses its VFS to manage nearly all named objects (pipes, locks, message
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queues, etc.). And it is a good policy for NuttX to do this too. NuttX already
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does this for things like drivers and mountpoints. Why not extend this mechanism
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to handle named, builtin applications too?
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**Proposed Configuration Options**
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The following configuration options are planned:
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* ``CONFIG_BUILTIN=y`` Will still be needed to enable NuttX support for
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builtin applications, and
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* ``CONFIG_NSH_BUILTIN_APPS=y`` Will still be needed enable to stimulate
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programs to register themselves as builtin applications.
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And in addition:
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* ``CONFIG_FS_BINFS=y`` Enable the BINFS file system that is used to access
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builtin applications as files,
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* ``CONFIG_LIBC_EXECFUNCS=y`` Enable support for ``execv()``, ``execl()``, and
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``posix_spawn()``,
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* ``CONFIG_NSH_FILE_APPS=y`` Enable execution of programs in a file system by NSH,
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* ``CONFIG_BINFMT_EXEPATH=y`` Enable the (optional) use of the path variable to
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find executable programs, and
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* ``CONFIG_PATH_INITIAL="/mnt/sdcard:/bin"`` Optional initial value of the
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PATH variable.
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**Example**
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When this feature is enable, will will be able to do this (where myapplication is
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the name of some, arbitrary "built-in" application):
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.. code-block:: bash
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NuttShell (NSH) NuttX-6.24
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nsh> mount -t binfs /bin
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nsh> ls -l /bin
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/bin:
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-rw-r--r-- 0 myapplication
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nsh> echo $PATH
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/mnt/sdcard:/bin
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nsh> myapplication
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... and your FLASH based application runs ...
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nsh>
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**Auto-Mounting BINFS**
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BINFS, like any file system, could be mounted by an startup script
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at ``/etc/init.d/rcS``.
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But since BINFS may be used in many configurations that don't otherwise
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need a startup script, perhaps some configurations would be helpful:
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* ``CONFIG_NSH_AUTOMOUNT_BINFS=y`` Automatically mount the BINFS file
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system on startup (**NOT implemented**)
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* ``CONFIG_NSH_BINFS_MOUNTPOINT="/bin"`` The BINFS mountpoint (NOT implemented).
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Or perhaps a better thing to do would just be to make it easier to add a
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startup script?
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**Next Steps**
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In the longer term, I would like to see an option to move most of the larger
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NSH commands out of RAM and built them as standalone programs that can reside,
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for example, on an SD card (**NOT implemented**).
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