Re: fileexist(f)

[Petr M. <mi...@ph...>]

>> 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.

No:

gnuplot> plot 'a.dat', 'bla'
                        ^
          can't read data file "bla"
          util.c: No such file or directory


>> Example 2:
>
> I do not follow you there at all.

It was not a good example, sorry.


So, I'll commit the "fileexist" patch which uses fopen().


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

Why? What about "select" and "stat" functions? If select() is not available, 
a poor-man solution is to check the status with one-second resolution.
(Well, I never used select() but I think it provides the waiting.)

---
PM