Tornado

5
Shell
side expression of the assignment statement. The shell prints a message indicating
that a new variable has been allocated and assigned the specified value.
For example, if the identifier fd is not currently in the symbol table, the following
statement creates a new variable named fd and assigns to it the result of the
function call:
-> fd = open ("file", 0)
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5.3.7 Comments
The shell allows two kinds of comments. First, comments of the form /* … */ can
be included anywhere on a shell input line. These comments are simply discarded,
and the rest of the input line evaluated as usual. Second, any line whose first
nonblank character is # is ignored completely. Comments are particularly useful
for Tornado shell scripts. See the section Scripts: Redirecting Shell I/O, p.189 below.
5.3.8 Strings
When the shell encounters a string literal ("…") in an expression, it allocates space
for the string including the null-byte string terminator. The value of the literal is
the address of the string in the newly allocated storage. For instance, the following
expression allocates 12 bytes from the target-agent memory pool, enters the string
in those 12 bytes (including the null terminator), and assigns the address of the
string to x:
-> x = "hello there"
Even when a string literal is not assigned to a symbol, memory is still permanently
allocated for it. For example, the following uses 12 bytes of memory that are never freed:
-> printf ("hello there")
If strings were only temporarily allocated, and a string literal were passed to a
routine being spawned as a task, then by the time the task executed and attempted
to access the string, the shell would have already released—possibly even
reused—the temporary storage where the string was held.
This memory, like other memory used by the Tornado tools, comes from the targetagent
memory pool; it does not reduce the amount of memory available for
application execution (the VxWorks memory pool). The amount of target memory
allocated for each of the two memory pools is defined at configuration time; see
Scaling the Target Agent, p.141.
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