source: rtems-docs/shell/general_commands.rst @ f916fca

General Commands
################

Introduction
============

The RTEMS shell has the following general commands:

- ``help`` - Print command help

- ``alias`` - Add alias for an existing command

- ``cmdls`` - List commands

- ``cmdchown`` - Change user or owner of commands

- ``cmdchmod`` - Change mode of commands

- ``date`` - Print or set current date and time

- ``echo`` - Produce message in a shell script

- ``sleep`` - Delay for a specified amount of time

- ``id`` - show uid gid euid and egid

- ``tty`` - show ttyname

- ``whoami`` - print effective user id

- ``getenv`` - print environment variable

- ``setenv`` - set environment variable

- ``unsetenv`` - unset environment variable

- ``time`` - time command execution

- ``logoff`` - logoff from the system

- ``rtc`` - RTC driver configuration

- ``exit`` - alias for logoff command

Commands
========

This section details the General Commands available.  A subsection is dedicated
to each of the commands and describes the behavior and configuration of that
command as well as providing an example usage.

help - Print command help
-------------------------
.. index:: help

**SYNOPSYS:**

.. code:: shell

    help misc

**DESCRIPTION:**

This command prints the command help. Help without arguments prints a list of
topics and help with a topic prints the help for that topic.

**EXIT STATUS:**

This command returns 0.

**NOTES:**

The help print will break the output up based on the environment variable
SHELL_LINES. If this environment variable is not set the default is 16
lines. If set the number of lines is set to that the value. If the shell lines
is set 0 there will be no break.

**EXAMPLES:**

The following is an example of how to use ``alias``:

.. code:: shell

    SHLL [/] $ help
    help: ('r' repeat last cmd - 'e' edit last cmd)
    TOPIC? The topics are
    mem, misc, files, help, rtems, network, monitor
    SHLL [/] $ help misc
    help: list for the topic 'misc'
    alias        - alias old new
    time         - time command [arguments...]
    joel         - joel [args] SCRIPT
    date         - date [YYYY-MM-DD HH:MM:SS]
    echo         - echo [args]
    sleep        - sleep seconds [nanoseconds]
    id           - show uid, gid, euid, and egid
    tty          - show ttyname
    whoami       - show current user
    logoff       - logoff from the system
    setenv       - setenv [var] [string]
    getenv       - getenv [var]
    unsetenv     - unsetenv [var]
    umask        - umask [new_umask]
    Press any key to continue...
    rtc          - real time clock read and set
    SHLL [/] $ setenv SHELL_ENV 0
    SHLL [/] $ help misc
    help: list for the topic 'misc'
    alias        - alias old new
    time         - time command [arguments...]
    joel         - joel [args] SCRIPT
    date         - date [YYYY-MM-DD HH:MM:SS]
    echo         - echo [args]
    sleep        - sleep seconds [nanoseconds]
    id           - show uid, gid, euid, and egid
    tty          - show ttyname
    whoami       - show current user
    logoff       - logoff from the system
    setenv       - setenv [var] [string]
    getenv       - getenv [var]
    unsetenv     - unsetenv [var]
    umask        - umask [new_umask]
    rtc          - real time clock read and set

**CONFIGURATION:**

This command has no configuration.

alias - add alias for an existing command
-----------------------------------------
.. index:: alias

**SYNOPSYS:**

.. code:: shell

    alias oldCommand newCommand

**DESCRIPTION:**

This command adds an alternate name for an existing command to the command set.

**EXIT STATUS:**

This command returns 0 on success and non-zero if an error is encountered.

**NOTES:**

None.

**EXAMPLES:**

The following is an example of how to use ``alias``:

.. code:: shell

    SHLL [/] $ me
    shell:me command not found
    SHLL [/] $ alias whoami me
    SHLL [/] $ me
    rtems
    SHLL [/] $ whoami
    rtems

**CONFIGURATION:**

.. index:: CONFIGURE_SHELL_NO_COMMAND_ALIAS
.. index:: CONFIGURE_SHELL_COMMAND_ALIAS

This command is included in the default shell command set.  When building a
custom command set, define ``CONFIGURE_SHELL_COMMAND_ALIAS`` to have this
command included.

This command can be excluded from the shell command set by defining
``CONFIGURE_SHELL_NO_COMMAND_ALIAS`` when all shell commands have been
configured.

**PROGRAMMING INFORMATION:**

.. index:: rtems_shell_rtems_main_alias

The ``alias`` is implemented by a C language function which has the following
prototype:

.. code:: c

    int rtems_shell_rtems_main_alias(
        int    argc,
        char **argv
    );

The configuration structure for the ``alias`` has the following prototype:

.. code:: c

    extern rtems_shell_cmd_t rtems_shell_ALIAS_Command;

cmdls - List commands
---------------------
.. index:: cmdls

**SYNOPSYS:**

.. code:: shell

    cmdls COMMAND...

**DESCRIPTION:**

This command lists the visible commands of the command set.

**EXIT STATUS:**

This command returns 0 on success and non-zero if an error is encountered.

**NOTES:**

The current user must have read permission to list a command.

**EXAMPLES:**

The following is an example of how to use ``cmdls``:

.. code:: shell

    SHLL [/] # cmdls help shutdown
    r-xr-xr-x     0     0 help
    r-x------     0     0 shutdown

**CONFIGURATION:**

.. index:: CONFIGURE_SHELL_NO_COMMAND_CMDLS
.. index:: CONFIGURE_SHELL_COMMAND_CMDLS

This command is included in the default shell command set.  When building a
custom command set, define ``CONFIGURE_SHELL_COMMAND_CMDLS`` to have this
command included.

This command can be excluded from the shell command set by defining
``CONFIGURE_SHELL_NO_COMMAND_CMDLS`` when all shell commands have been
configured.

**PROGRAMMING INFORMATION:**

The configuration structure for the ``cmdls`` has the following prototype:

.. code:: c

    extern rtems_shell_cmd_t rtems_shell_CMDLS_Command;

cmdchown - Change user or owner of commands
-------------------------------------------
.. index:: cmdchown

**SYNOPSYS:**

.. code:: shell

    cmdchown [OWNER][:[GROUP]] COMMAND...

**DESCRIPTION:**

This command changes the user or owner of a command.

**EXIT STATUS:**

This command returns 0 on success and non-zero if an error is encountered.

**NOTES:**

The current user must have an UID of zero or be the command owner to change the
owner or group.

**EXAMPLES:**

The following is an example of how to use ``cmdchown``:

.. code:: shell

    [/] # cmdls help
    r-xr-xr-x     0     0 help
    [/] # cmdchown 1:1 help
    [/] # cmdls help
    r--r--r--     1     1 help

**CONFIGURATION:**

.. index:: CONFIGURE_SHELL_NO_COMMAND_CMDCHOWN
.. index:: CONFIGURE_SHELL_COMMAND_CMDCHOWN

This command is included in the default shell command set.  When building a
custom command set, define ``CONFIGURE_SHELL_COMMAND_CMDCHOWN`` to have this
command included.

This command can be excluded from the shell command set by defining
``CONFIGURE_SHELL_NO_COMMAND_CMDCHOWN`` when all shell commands have been
configured.

**PROGRAMMING INFORMATION:**

The configuration structure for the ``cmdchown`` has the following prototype:

.. code:: c

    extern rtems_shell_cmd_t rtems_shell_CMDCHOWN_Command;

cmdchmod - Change mode of commands
----------------------------------
.. index:: cmdchmod

**SYNOPSYS:**

.. code:: shell

    cmdchmod OCTAL-MODE COMMAND...

**DESCRIPTION:**

This command changes the mode of a command.

**EXIT STATUS:**

This command returns 0 on success and non-zero if an error is encountered.

**NOTES:**

The current user must have an UID of zero or be the command owner to change the
mode.

**EXAMPLES:**

The following is an example of how to use ``cmdchmod``:

.. code:: shell

    [/] # cmdls help
    r-xr-xr-x     0     0 help
    [/] # cmdchmod 544 help
    [/] # cmdls help
    r-xr--r--     0     0 help

**CONFIGURATION:**

.. index:: CONFIGURE_SHELL_NO_COMMAND_CMDCHMOD
.. index:: CONFIGURE_SHELL_COMMAND_CMDCHMOD

This command is included in the default shell command set.  When building a
custom command set, define ``CONFIGURE_SHELL_COMMAND_CMDCHMOD`` to have this
command included.

This command can be excluded from the shell command set by defining
``CONFIGURE_SHELL_NO_COMMAND_CMDCHMOD`` when all shell commands have been
configured.

**PROGRAMMING INFORMATION:**

The configuration structure for the ``cmdchmod`` has the following prototype:

.. code:: c

    extern rtems_shell_cmd_t rtems_shell_CMDCHMOD_Command;

date - print or set current date and time
-----------------------------------------
.. index:: date

**SYNOPSYS:**

.. code:: shell

    date
    date DATE TIME

**DESCRIPTION:**

This command operates one of two modes.  When invoked with no arguments, it
prints the current date and time.  When invoked with both ``date`` and ``time``
arguments, it sets the current time.

The ``date`` is specified in ``YYYY-MM-DD`` format.
The ``time`` is specified in ``HH:MM:SS`` format.

**EXIT STATUS:**

This command returns 0 on success and non-zero if an error is encountered.

**NOTES:**

None.

**EXAMPLES:**

The following is an example of how to use ``date``:

.. code:: shell

    SHLL [/] $ date
    Fri Jan  1 00:00:09 1988
    SHLL [/] $ date 2008-02-29 06:45:32
    SHLL [/] $ date
    Fri Feb 29 06:45:35 2008

**CONFIGURATION:**

.. index:: CONFIGURE_SHELL_NO_COMMAND_DATE
.. index:: CONFIGURE_SHELL_COMMAND_DATE

This command is included in the default shell command set.  When building a
custom command set, define ``CONFIGURE_SHELL_COMMAND_DATE`` to have this command
included.

This command can be excluded from the shell command set by defining
``CONFIGURE_SHELL_NO_COMMAND_DATE`` when all shell commands have been
configured.

**PROGRAMMING INFORMATION:**

.. index:: rtems_shell_rtems_main_date

The ``date`` is implemented by a C language function which has the following
prototype:

.. code:: c

    int rtems_shell_rtems_main_date(
        int    argc,
        char **argv
    );

The configuration structure for the ``date`` has the following prototype:

.. code:: c

    extern rtems_shell_cmd_t rtems_shell_DATE_Command;

echo - produce message in a shell script
----------------------------------------
.. index:: echo

**SYNOPSYS:**

.. code:: shell

    echo [-n | -e] args ...

**DESCRIPTION:**

Echo prints its arguments on the standard output, separated by spaces.  Unless
the *-n* option is present, a newline is output following the arguments.  The
*-e* option causes echo to treat the escape sequences specially, as described
in the following paragraph.  The *-e* option is the default, and is provided
solely for compatibility with other systems.  Only one of the options *-n* and
*-e* may be given.

If any of the following sequences of characters is encountered during output,
the sequence is not output.  Instead, the specified action is performed:

*\\b*
    A backspace character is output.

*\\c*
    Subsequent output is suppressed.  This is normally used at the end of the
    last argument to suppress the trailing newline that echo would otherwise
    output.

*\\f*
    Output a form feed.

*\\n*
    Output a newline character.

*\\r*
    Output a carriage return.

*\\t*
    Output a (horizontal) tab character.

*\\v*
    Output a vertical tab.

*\\0digits*
    Output the character whose value is given by zero to three digits.  If
    there are zero digits, a nul character is output.

*\\\\*
    Output a backslash.

**EXIT STATUS:**

This command returns 0 on success and non-zero if an error is encountered.

**NOTES:**

The octal character escape mechanism (\\0digits) differs from the C language
mechanism.

There is no way to force ``echo`` to treat its arguments literally, rather than
interpreting them as options and escape sequences.

**EXAMPLES:**

The following is an example of how to use ``echo``:

.. code:: shell

    SHLL [/] $ echo a b c
    a b c
    SHLL [/] $ echo

**CONFIGURATION:**

.. index:: CONFIGURE_SHELL_NO_COMMAND_ECHO
.. index:: CONFIGURE_SHELL_COMMAND_ECHO

This command is included in the default shell command set.  When building a
custom command set, define ``CONFIGURE_SHELL_COMMAND_ECHO`` to have this command
included.

This command can be excluded from the shell command set by defining
``CONFIGURE_SHELL_NO_COMMAND_ECHO`` when all shell commands have been
configured.

**PROGRAMMING INFORMATION:**

.. index:: rtems_shell_rtems_main_echo

The ``echo`` is implemented by a C language function which has the following
prototype:

.. code:: c

    int rtems_shell_rtems_main_echo(
        int    argc,
        char **argv
    );

The configuration structure for the ``echo`` has the following prototype:

.. code:: c

    extern rtems_shell_cmd_t rtems_shell_ECHO_Command;

**ORIGIN:**

The implementation and portions of the documentation for this command are from
NetBSD 4.0.

sleep - delay for a specified amount of time
--------------------------------------------
.. index:: sleep

**SYNOPSYS:**

.. code:: shell

    sleep seconds
    sleep seconds nanoseconds

**DESCRIPTION:**

This command causes the task executing the shell to block for the specified
number of ``seconds`` and ``nanoseconds``.

**EXIT STATUS:**

This command returns 0 on success and non-zero if an error is encountered.

**NOTES:**

This command is implemented using the ``nanosleep()`` method.

The command line interface is similar to the ``sleep`` command found on POSIX
systems but the addition of the ``nanoseconds`` parameter allows fine grained
delays in shell scripts without adding another command such as ``usleep``.

**EXAMPLES:**

The following is an example of how to use ``sleep``:

.. code:: shell

    SHLL [/] $ sleep 10
    SHLL [/] $ sleep 0 5000000

It is not clear from the above but there is a ten second pause after executing
the first command before the prompt is printed.  The second command completes
very quickly from a human perspective and there is no noticeable delay in the
prompt being printed.

**CONFIGURATION:**

.. index:: CONFIGURE_SHELL_NO_COMMAND_SLEEP
.. index:: CONFIGURE_SHELL_COMMAND_SLEEP

This command is included in the default shell command set.  When building a
custom command set, define ``CONFIGURE_SHELL_COMMAND_SLEEP`` to have this
command included.

This command can be excluded from the shell command set by defining
``CONFIGURE_SHELL_NO_COMMAND_SLEEP`` when all shell commands have been
configured.

**PROGRAMMING INFORMATION:**

.. index:: rtems_shell_rtems_main_sleep

The ``sleep`` is implemented by a C language function which has the following
prototype:

.. code:: c

    int rtems_shell_rtems_main_sleep(
        int    argc,
        char **argv
    );

The configuration structure for the ``sleep`` has the following prototype:

.. code:: c

    extern rtems_shell_cmd_t rtems_shell_SLEEP_Command;

id - show uid gid euid and egid
-------------------------------
.. index:: id

**SYNOPSYS:**

.. code:: shell

    id

**DESCRIPTION:**

This command prints the user identity.  This includes the user id (uid), group
id (gid), effective user id (euid), and effective group id (egid).

**EXIT STATUS:**

This command returns 0 on success and non-zero if an error is encountered.

**NOTES:**

Remember there is only one POSIX process in a single processor RTEMS
application. Each thread may have its own user identity and that identity is
used by the filesystem to enforce permissions.

**EXAMPLES:**

The first example of the ``id`` command is from a session logged
in as the normal user ``rtems``:

.. code:: shell

    SHLL [/] # id
    uid=1(rtems),gid=1(rtems),euid=1(rtems),egid=1(rtems)

The second example of the ``id`` command is from a session logged in as the
``root`` user:

.. code:: shell

    SHLL [/] # id
    uid=0(root),gid=0(root),euid=0(root),egid=0(root)

**CONFIGURATION:**

.. index:: CONFIGURE_SHELL_NO_COMMAND_ID
.. index:: CONFIGURE_SHELL_COMMAND_ID

This command is included in the default shell command set.  When building a
custom command set, define ``CONFIGURE_SHELL_COMMAND_ID`` to have this command
included.

This command can be excluded from the shell command set by defining
``CONFIGURE_SHELL_NO_COMMAND_ID`` when all shell commands have been configured.

**PROGRAMMING INFORMATION:**

.. index:: rtems_shell_rtems_main_id

The ``id`` is implemented by a C language function which has the following
prototype:

.. code:: c

    int rtems_shell_rtems_main_id(
        int    argc,
        char **argv
    );

The configuration structure for the ``id`` has the following prototype:

.. code:: c

    extern rtems_shell_cmd_t rtems_shell_ID_Command;

tty - show ttyname
------------------
.. index:: tty

**SYNOPSYS:**

.. code:: shell

    tty

**DESCRIPTION:**

This command prints the file name of the device connected to standard input.

**EXIT STATUS:**

This command returns 0 on success and non-zero if an error is encountered.

**NOTES:**

NONE

**EXAMPLES:**

The following is an example of how to use ``tty``:

.. code:: shell

    SHLL [/] $ tty
    /dev/console

**CONFIGURATION:**

.. index:: CONFIGURE_SHELL_NO_COMMAND_TTY
.. index:: CONFIGURE_SHELL_COMMAND_TTY

This command is included in the default shell command set.  When building a
custom command set, define ``CONFIGURE_SHELL_COMMAND_TTY`` to have this command
included.

This command can be excluded from the shell command set by defining
``CONFIGURE_SHELL_NO_COMMAND_TTY`` when all shell commands have been
configured.

**PROGRAMMING INFORMATION:**

.. index:: rtems_shell_rtems_main_tty

The ``tty`` is implemented by a C language function which has the following
prototype:

.. code:: c

    int rtems_shell_rtems_main_tty(
        int    argc,
        char **argv
    );

The configuration structure for the ``tty`` has the following prototype:

.. code:: c

    extern rtems_shell_cmd_t rtems_shell_TTY_Command;

whoami - print effective user id
--------------------------------
.. index:: whoami

**SYNOPSYS:**

.. code:: shell

    whoami

**DESCRIPTION:**

This command displays the user name associated with the current effective user
id.

**EXIT STATUS:**

This command always succeeds.

**NOTES:**

None.

**EXAMPLES:**

The following is an example of how to use ``whoami``:

.. code:: shell

    SHLL [/] $ whoami
    rtems

**CONFIGURATION:**

.. index:: CONFIGURE_SHELL_NO_COMMAND_WHOAMI
.. index:: CONFIGURE_SHELL_COMMAND_WHOAMI

This command is included in the default shell command set.  When building a
custom command set, define ``CONFIGURE_SHELL_COMMAND_WHOAMI`` to have this
command included.

This command can be excluded from the shell command set by defining
``CONFIGURE_SHELL_NO_COMMAND_WHOAMI`` when all shell commands have been
configured.

**PROGRAMMING INFORMATION:**

.. index:: rtems_shell_rtems_main_whoami

The ``whoami`` is implemented by a C language function which has the following
prototype:

.. code:: c

    int rtems_shell_rtems_main_whoami(
        int    argc,
        char **argv
    );

The configuration structure for the ``whoami`` has the following prototype:

.. code:: c

    extern rtems_shell_cmd_t rtems_shell_WHOAMI_Command;

getenv - print environment variable
-----------------------------------
.. index:: getenv

**SYNOPSYS:**

.. code:: shell

    getenv variable

**DESCRIPTION:**

This command is used to display the value of a ``variable`` in the set of
environment variables.

**EXIT STATUS:**

This command will return 1 and print a diagnostic message if a failure occurs.

**NOTES:**

The entire RTEMS application shares a single set of environment variables.

**EXAMPLES:**

The following is an example of how to use ``getenv``:

.. code:: shell

    SHLL [/] $ getenv BASEPATH
    /mnt/hda1

**CONFIGURATION:**

.. index:: CONFIGURE_SHELL_NO_COMMAND_GETENV
.. index:: CONFIGURE_SHELL_COMMAND_GETENV

This command is included in the default shell command set.  When building a
custom command set, define ``CONFIGURE_SHELL_COMMAND_GETENV`` to have this
command included.

This command can be excluded from the shell command set by defining
``CONFIGURE_SHELL_NO_COMMAND_GETENV`` when all shell commands have been
configured.

**PROGRAMMING INFORMATION:**

.. index:: rtems_shell_rtems_main_getenv

The ``getenv`` is implemented by a C language function which has the following
prototype:

.. code:: c

    int rtems_shell_rtems_main_getenv(
        int    argc,
        char **argv
    );

The configuration structure for the ``getenv`` has the following prototype:

.. code:: c

    extern rtems_shell_cmd_t rtems_shell_GETENV_Command;

setenv - set environment variable
---------------------------------
.. index:: setenv

**SYNOPSYS:**

.. code:: shell

    setenv variable [value]

**DESCRIPTION:**

This command is used to add a new ``variable`` to the set of environment
variables or to modify the variable of an already existing ``variable``.  If
the ``value`` is not provided, the ``variable`` will be set to the empty
string.

**EXIT STATUS:**

This command will return 1 and print a diagnostic message if a failure occurs.

**NOTES:**

The entire RTEMS application shares a single set of environment variables.

**EXAMPLES:**

The following is an example of how to use ``setenv``:

.. code:: shell

    SHLL [/] $ setenv BASEPATH /mnt/hda1

**CONFIGURATION:**

.. index:: CONFIGURE_SHELL_NO_COMMAND_SETENV
.. index:: CONFIGURE_SHELL_COMMAND_SETENV

This command is included in the default shell command set.  When building a
custom command set, define ``CONFIGURE_SHELL_COMMAND_SETENV`` to have this
command included.

This command can be excluded from the shell command set by defining
``CONFIGURE_SHELL_NO_COMMAND_SETENV`` when all shell commands have been
configured.

**PROGRAMMING INFORMATION:**

.. index:: rtems_shell_rtems_main_setenv

The ``setenv`` is implemented by a C language function which has the following
prototype:

.. code:: c

    int rtems_shell_rtems_main_setenv(
        int    argc,
        char **argv
    );

The configuration structure for the ``setenv`` has the following prototype:

.. code:: c

    extern rtems_shell_cmd_t rtems_shell_SETENV_Command;

unsetenv - unset environment variable
-------------------------------------
.. index:: unsetenv

**SYNOPSYS:**

.. code:: shell

    unsetenv variable

**DESCRIPTION:**

This command is remove to a ``variable`` from the set of environment variables.

**EXIT STATUS:**

This command will return 1 and print a diagnostic message if a failure occurs.

**NOTES:**

The entire RTEMS application shares a single set of environment variables.

**EXAMPLES:**

The following is an example of how to use ``unsetenv``:

.. code:: shell

    SHLL [/] $ unsetenv BASEPATH

**CONFIGURATION:**

.. index:: CONFIGURE_SHELL_NO_COMMAND_UNSETENV
.. index:: CONFIGURE_SHELL_COMMAND_UNSETENV

This command is included in the default shell command set.  When building a
custom command set, define ``CONFIGURE_SHELL_COMMAND_UNSETENV`` to have this
command included.

This command can be excluded from the shell command set by defining
``CONFIGURE_SHELL_NO_COMMAND_UNSETENV`` when all shell commands have been
configured.

**PROGRAMMING INFORMATION:**

.. index:: rtems_shell_rtems_main_unsetenv

The ``unsetenv`` is implemented by a C language function which has the
following prototype:

.. code:: c

    int rtems_shell_rtems_main_unsetenv(
        int    argc,
        char **argv
    );

The configuration structure for the ``unsetenv`` has the following prototype:

.. code:: c

    extern rtems_shell_cmd_t rtems_shell_UNSETENV_Command;

time - time command execution
-----------------------------
.. index:: time

**SYNOPSYS:**

.. code:: c

    time command [argument ...]

**DESCRIPTION:**

The time command executes and times a command.  After the command finishes,
time writes the total time elapsed.  Times are reported in seconds.

**EXIT STATUS:**

This command returns 0 on success and non-zero if an error is encountered.

**NOTES:**

None.

**EXAMPLES:**

The following is an example of how to use ``time``:

.. code:: shell

    SHLL [/] $ time cp -r /nfs/directory /c

**CONFIGURATION:**

.. index:: CONFIGURE_SHELL_NO_COMMAND_TIME
.. index:: CONFIGURE_SHELL_COMMAND_TIME

This command is included in the default shell command set.  When building a
custom command set, define ``CONFIGURE_SHELL_COMMAND_TIME`` to have this command
included.

This command can be excluded from the shell command set by defining
``CONFIGURE_SHELL_NO_COMMAND_TIME`` when all shell commands have been
configured.

**PROGRAMMING INFORMATION:**

.. index:: rtems_shell_rtems_main_time

The ``time`` is implemented by a C language function which has the following
prototype:

.. code:: c

    int rtems_shell_rtems_main_time(
        int    argc,
        char **argv
    );

The configuration structure for the ``time`` has the following prototype:

.. code:: c

    extern rtems_shell_cmd_t rtems_shell_TIME_Command;

logoff - logoff from the system
-------------------------------
.. index:: logoff

**SYNOPSYS:**

.. code:: shell

    logoff

**DESCRIPTION:**

This command logs the user out of the shell.

**EXIT STATUS:**

This command does not return.

**NOTES:**

The system behavior when the shell is exited depends upon how the shell was
initiated.  The typical behavior is that a login prompt will be displayed for
the next login attempt or that the connection will be dropped by the RTEMS
system.

**EXAMPLES:**

The following is an example of how to use ``logoff``:

.. code:: shell

    SHLL [/] $ logoff
    logoff from the system...

**CONFIGURATION:**

.. index:: CONFIGURE_SHELL_NO_COMMAND_LOGOFF
.. index:: CONFIGURE_SHELL_COMMAND_LOGOFF

This command is included in the default shell command set.  When building a
custom command set, define ``CONFIGURE_SHELL_COMMAND_LOGOFF`` to have this
command included.

This command can be excluded from the shell command set by defining
``CONFIGURE_SHELL_NO_COMMAND_LOGOFF`` when all shell commands have been
configured.

**PROGRAMMING INFORMATION:**

.. index:: rtems_shell_rtems_main_logoff

The ``logoff`` is implemented by a C language function which has the following
prototype:

.. code:: c

    int rtems_shell_rtems_main_logoff(
        int    argc,
        char **argv
    );

The configuration structure for the ``logoff`` has the following prototype:

.. code:: c

    extern rtems_shell_cmd_t rtems_shell_LOGOFF_Command;

rtc - RTC driver configuration
------------------------------
.. index:: rtc

**SYNOPSYS:**

.. code:: shell

    rtc

**CONFIGURATION:**

.. index:: CONFIGURE_SHELL_NO_COMMAND_RTC
.. index:: CONFIGURE_SHELL_COMMAND_RTC

This command is included in the default shell command set.  When building a
custom command set, define ``CONFIGURE_SHELL_COMMAND_RTC`` to have this command
included.

This command can be excluded from the shell command set by defining
``CONFIGURE_SHELL_NO_COMMAND_RTC`` when all shell commands have been
configured.

exit - exit the shell
---------------------
.. index:: exit

**SYNOPSYS:**

.. code:: shell

    exit

**DESCRIPTION:**

This command causes the shell interpreter to ``exit``.

**EXIT STATUS:**

This command does not return.

**NOTES:**

In contrast to `logoff - logoff from the system`, this command is built into
the shell interpreter loop.

**EXAMPLES:**

The following is an example of how to use ``exit``:

.. code:: shell

    SHLL [/] $ exit
    Shell exiting

**CONFIGURATION:**

This command is always present and cannot be disabled.

**PROGRAMMING INFORMATION:**

The ``exit`` is implemented directly in the shell interpreter.  There is no C
routine associated with it.