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Disabling buffering at RunProgram
Posted: Mon Jan 18, 2021 7:41 pm
by wb2k
Does anyone know how I can disable buffering at RunProgram?
When I execute gpupdate in an command-window it writes "Updating policy ..." immediately after I started it, but when executed via PureBasic's RunProgram it looks like there is no output until the gpupdate exits:
Code: Select all
handle = RunProgram("gpupdate", "", "", #PB_Program_Open | #PB_Program_Read | #PB_Program_Error)
While ProgramRunning(handle)
Debug "Running ..."
If AvailableProgramOutput(handle)
Debug "Output: " + ReadProgramString(handle)
EndIf
Delay(500)
Wend
Re: Disabling buffering at RunProgram
Posted: Mon Jan 18, 2021 8:07 pm
by Kiffi
Some programs write their output to stderr. Try ReadProgramError().
Re: Disabling buffering at RunProgram
Posted: Mon Jan 18, 2021 8:18 pm
by wb2k
Kiffi wrote:Some programs write their output to stderr. Try ReadProgramError().
stderr is empty, gpupdate writes to stdout.
The expected output is there at ReadProgramString(), but too late.
Re: Disabling buffering at RunProgram
Posted: Mon Jan 18, 2021 9:59 pm
by Ajm
If you try with ReadProgramData does that receive it. Maybe gpupdate is not terminating the string until the end.
Re: Disabling buffering at RunProgram
Posted: Mon Jan 18, 2021 10:41 pm
by wb2k
Ajm wrote:If you try with ReadProgramData does that receive it. Maybe gpupdate is not terminating the string until the end.
AvailableProgramOutput() would return true if there is any output (even non-terminating).
In the test-code it is executing the If-branch only near the end of gpupdate, so ReadProgramData won't make any difference.
Re: Disabling buffering at RunProgram
Posted: Tue Jan 19, 2021 3:46 pm
by Axolotl
wb2k, if I were you I would give the suggestion made by Ajm a try.
IMHO a closer look at the documentation gives some advice about that.
https://www.purebasic.com/documentation ... utput.html
Result = AvailableProgramOutput(Program)
The number of bytes available to be read from the programs output.
https://www.purebasic.com/documentation ... tring.html
Result$ = ReadProgramString(Program [, Flags])
This function also waits
until a full line of output is available. If not line-based or raw output is to be read, ReadProgramData() may be used.
This could be interpreted as waiting for a cr+lf, don't you think?
Re: Disabling buffering at RunProgram
Posted: Tue Jan 19, 2021 4:03 pm
by BarryG
It's just a cmd box issue, because if you redirect the output like this from a cmd box:
Then the text file is NOT updated until the very end, either - just like PureBasic.
Same if you send the output to the clipboard with "gpupdate | clip" - the clipboard doesn't get updated until the very end, again just like PureBasic.
Conclusion: Nothing you can do, wb2k.