Re: gnuplot error code

[<pl...@pi...>]

On 04/02/17 04:14, sfeam wrote:
> On Saturday, 04 February 2017 01:17:25 AM :	pl...@pi... wrote:
>> Hi,
>>
>> I am calling gnuplot as a child process and need to conditionally return
>> a non zero error code in some circumstances. From a quick search it
>> seems that this is not possible, It always returns zero: yet that seems
>> a little surprising.
>>
>> perl -e 'system("gnuplot -e \"exit 1;\""); print "$?\n"'
>>
>> The only way I can get a non zero result is if there is a parsing error
>> in the gnuplot commands.
>>
>> I am using gnuplot to display real time data on a server and it would be
>> good to be able to do some basic error trapping, not least for
>> debugging. Is there a way to do this?
>
> Correct. There is no way to control the gnuplot exit value.
>
>

Thanks for the confirmation, Ethan.

Would this be a worthwhile feature to add? I'm thinking of something 
like the awk exit which allows an optional  integer argument to  return.

if ( ! happy ) { print "not happy" ; exit 1; )

gnuplot is an excellent tool for plotting real time data on embedded 
devices to provide real time graphic output but obviously the 
possibility to exit with an error condition can be helpful, firstly in 
debugging and also trapping possible error conditions with a meaningful 
response should they happen.

The current behaviour is just jexit 0 , for backwards compat, some 
thought would need to be given to current non zero return in case of a 
syntax error in a gnuplot script but this does not seem to raise any 
conflict for those trapping current behaviour.

Peter.