RTEMS 4.9.1 On-Line Library

General Commands echo - produce message in a shell script

RTEMS Shell User's Guide

2.2.3: 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 lan- guage 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.

RTEMS Shell User's Guide