Martijn Dekker <[email protected]> wrote:
> On FreeBSD sh, when you set the export attribute on an otherwise unset
> variable, an empty environment variable is exported, though the variable
> continues to be considered unset within the current shell. This is the
> only shell I know of that does this.
A shell variable has four possible states, but two of them are not
distibguishable (state 1) and 2)) outside the iunternal shell implementation.
1) Variable does not exist - no related node exists.
2) Variable exists but is unset - this results in a NULL pointer
for the value of an existing variable node.
3) Variable is null, this results in a value that points to an empty
string.
4) Variable is non-null, the value points to a non-empty string.
If you call "export" or "unset", a variable needs to be created in order to be
able to store the flags (e.g. the export flag) for that variable. This creates
a variable in state (2).
State 1) and state 2) are both seen as a variable that "does not exist" or is
unset. This is since calling "unset" on a variable in state 1), 3) or 4)
crerates a variable in state 2).
Since there seem to be an agreement that the FreeBSD behavior is wrong, I do
not need to write more.
Jörg
--
EMail:[email protected] (home) Jörg Schilling D-13353 Berlin
[email protected] (work) Blog: http://schily.blogspot.com/
URL: http://cdrecord.org/private/ http://sf.net/projects/schilytools/files/'
