DESCRIPTIONThe ION Load/Go system enables the execution of ION administrative programs at remote nodes:
The lgsend program reads a Load/Go source file from a local file system,
encapsulates the text of that source file in a bundle, and sends the bundle
to a designated DTN endpoint on the remote node.
An lgagent task running on the remote node, which has opened that DTN endpoint for bundle reception, receives the extracted payload of the bundle --- the text of the Load/Go source file --- and processes it.
Load/Go source file content is limited to newline-terminated lines of ASCII characters. More specifically, the text of any Load/Go source file is a sequence of line sets of two types: file capsules and directives. Any Load/Go source file may contain any number of file capsules and any number of directives, freely intermingled in any order, but the typical structure of a Load/Go source file is simply a single file capsule followed by a single directive.
Each file capsule is structured as a single start-of-capsule line, followed by zero or more capsule text lines, followed by a single end-of-capsule line. Each start-of-capsule line is of this form:
Each capsule text line can be any line of ASCII text that does not begin with an opening ([) or closing (]) bracket character.
A text line that begins with a closing bracket character (]) is interpreted as an end-of-capsule line.
A directive is any line of text that is not one of the lines of a file capsule and that is of this form:
When lgagent identifies a file capsule, it copies all of the capsule's text lines to a new file named file_name that it creates in the current working directory. When lgagent identifies a directive, it executes the directive by passing directive_text to the pseudoshell() function (see platform(3)). lgagent processes the line sets of a Load/Go source file in the order in which they appear in the file, so the directive_text of a directive may reference a file that was created as the result of processing a prior file capsule line set in the same source file.
Note that lgfile directives are passed to pseudoshell(), which on a VxWorks platform will always spawn a new task; the first argument in directive_text must be a symbol that VxWorks can resolve to a function, not a shell command. Also note that the arguments in directive_text will be actual task arguments, not shell command-line arguments, so they should never be enclosed in double-quote characters ("). However, any argument that contains embedded whitespace must be enclosed in single-quote characters (') so that pseudoshell() can parse it correctly.
EXAMPLESPresenting the following lines of source file text to lgsend:
x protocol ltp
should cause the receiving node to halt the operation of the LTP convergence-layer protocol.