Re: fileexist(f)

[Ethan M. <merritt@u.washington.edu>]

On Friday 03 March 2006 02:25 am, Petr Mikulik wrote:
> > Can you give an example of why such a thing is needed?
>
> Example 1:
> plot 'measure.dat'
> if fileexist('fit.dat') replot 'fit.dat'
> pause 5
> reread

So far as I know, with the current cvs version you might
just as well say
  plot 'measure.dat','fit.dat'
  pause 5
  reread

A missing data file should no longer prevents the plot from being
constructed.



> Example 2:
> Execution of commands passed via pipes between gnuplot and octave
> (for example) takes some time and it's hard to stop/wait without
> breaking the script (error message). The above solution is fine for
> some cases.

I do not follow you there at all.
Neither your `test` nor your access() or fopen() will work on a pipe.

> Actually, what some users ask for real-time plotting, is something
> like 
>    pause untilfilechanged "next.dat" 

I doubt there is a universally portable solution to this one.
It is difficult even if you restrict the solution to linux/unix.
The best I can think of without writing an external helper that
monitors the file is something like:

   ready = words(system("find . -name 'next.dat' -newer 'lock'"))
   if (ready) plot "next.dat"
   if (ready) system("touch lock")
   pause 1
   reread



-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle WA