3. General Commands¶

3.1. 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

3.2. 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.

3.2.1. help - Print command help¶

SYNOPSYS:

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:

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.

3.2.2. alias - add alias for an existing command¶

SYNOPSYS:

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:

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

CONFIGURATION:

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:

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

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

The configuration structure for the alias has the following prototype:

extern rtems_shell_cmd_t rtems_shell_ALIAS_Command;

3.2.3. cmdls - List commands¶

SYNOPSYS:

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:

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

CONFIGURATION:

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:

extern rtems_shell_cmd_t rtems_shell_CMDLS_Command;

3.2.4. cmdchown - Change user or owner of commands¶

SYNOPSYS:

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:

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

CONFIGURATION:

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:

extern rtems_shell_cmd_t rtems_shell_CMDCHOWN_Command;

3.2.5. cmdchmod - Change mode of commands¶

SYNOPSYS:

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:

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

CONFIGURATION:

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:

extern rtems_shell_cmd_t rtems_shell_CMDCHMOD_Command;

3.2.6. date - print or set current date and time¶

SYNOPSYS:

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:

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:

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:

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

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

The configuration structure for the date has the following prototype:

extern rtems_shell_cmd_t rtems_shell_DATE_Command;

3.2.7. echo - produce message in a shell script¶

SYNOPSYS:

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:

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

CONFIGURATION:

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:

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

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

The configuration structure for the echo has the following prototype:

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.

3.2.8. sleep - delay for a specified amount of time¶

SYNOPSYS:

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:

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:

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:

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

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

The configuration structure for the sleep has the following prototype:

extern rtems_shell_cmd_t rtems_shell_SLEEP_Command;

3.2.9. id - show uid gid euid and egid¶

SYNOPSYS:

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:

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:

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

CONFIGURATION:

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:

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

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

The configuration structure for the id has the following prototype:

extern rtems_shell_cmd_t rtems_shell_ID_Command;

3.2.10. tty - show ttyname¶

SYNOPSYS:

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:

SHLL [/] $ tty
/dev/console

CONFIGURATION:

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:

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

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

The configuration structure for the tty has the following prototype:

extern rtems_shell_cmd_t rtems_shell_TTY_Command;

3.2.11. whoami - print effective user id¶

SYNOPSYS:

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:

SHLL [/] $ whoami
rtems

CONFIGURATION:

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:

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

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

The configuration structure for the whoami has the following prototype:

extern rtems_shell_cmd_t rtems_shell_WHOAMI_Command;

3.2.12. getenv - print environment variable¶

SYNOPSYS:

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:

SHLL [/] $ getenv BASEPATH
/mnt/hda1

CONFIGURATION:

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:

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

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

The configuration structure for the getenv has the following prototype:

extern rtems_shell_cmd_t rtems_shell_GETENV_Command;

3.2.13. setenv - set environment variable¶

SYNOPSYS:

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:

SHLL [/] $ setenv BASEPATH /mnt/hda1

CONFIGURATION:

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:

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

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

The configuration structure for the setenv has the following prototype:

extern rtems_shell_cmd_t rtems_shell_SETENV_Command;

3.2.14. unsetenv - unset environment variable¶

SYNOPSYS:

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:

SHLL [/] $ unsetenv BASEPATH

CONFIGURATION:

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:

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

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

The configuration structure for the unsetenv has the following prototype:

extern rtems_shell_cmd_t rtems_shell_UNSETENV_Command;

3.2.15. time - time command execution¶

SYNOPSYS:

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:

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

CONFIGURATION:

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:

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

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

The configuration structure for the time has the following prototype:

extern rtems_shell_cmd_t rtems_shell_TIME_Command;

3.2.16. logoff - logoff from the system¶

SYNOPSYS:

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:

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

CONFIGURATION:

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:

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

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

The configuration structure for the logoff has the following prototype:

extern rtems_shell_cmd_t rtems_shell_LOGOFF_Command;

3.2.17. rtc - RTC driver configuration¶

SYNOPSYS:

rtc

CONFIGURATION:

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.

3.2.18. exit - exit the shell¶

SYNOPSYS:

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:

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.