Re: fc (history) requires zsh is interactive? Why can't interactive toggled?

[Peter Stephenson <pws@xxxxxxx>]

On Sun, 21 Sep 2008 20:37:13 -0400
"Rocky Bernstein" <rocky.bernstein@xxxxxxxxx> wrote:
> When I run fc -l (history) from a zsh script that isn't interactive I get
> the message
>  not interactive shell
> 
> Why is it that fc -l needs an interactive shell? One can put entries in the
> history and one can use vared to cycle through them, so what is it about an
> interactive shell that is important here?

When non-interactive, history isn't loaded at the start and needs loading
for the command you're running or by special interaction.  So "fc -l"
hasn't been very useful and the error message tends to be more helpful than
simply doing nothing because you're in a non-interactive shell with, the
vast majority of the time, no history.  There's no basic reason why it
shouldn't work if history works elsewhere.

> Related to this, why can't an interactive shell be toggled?

No basic reason, again, but it's a complicated support nightmare making
things changeable at run time rather than, as now, once when the shell
starts up.  For example, turning on job control in the middle of a
hitherto non-interactive shell changes the nature of what's stored in the
job table.  All that could in principle be fixed, it's just work, and
likely to be fairly low priority since we have very little effort
available for new large-scale tasks, particularly those which are
liable to introduce bugs.

-- 
Peter Stephenson <pws@xxxxxxx>                  Software Engineer
CSR PLC, Churchill House, Cambridge Business Park, Cowley Road
Cambridge, CB4 0WZ, UK                          Tel: +44 (0)1223 692070