Thanks for that, now I have another issue.
Unlike a piped open, open 3 does not seem to produce output immediately
Is there any way to use pipes with open3 so that the FH has content before
looping
ie: this produces output
my $pid=open($file, "-|","$cmd{$sopts->{subname}} 2>&1")
while
$pid=open3(undef,undef,$file,$cmdprog, @args)
does not until you iterate over the FH
thanks
On 10 July 2017 at 07:13, Chas. Owens <chas.ow...@gmail.com> wrote:
> On Sun, Jul 9, 2017, 19:37 Mike Martin <redt...@gmail.com> wrote:
>
>> Hi
>> I am trying to use Open3 to capture stderr and avoiding the shell ie:
>> my $str="-v 35 -i /data/Downloads/testinput.mp4 -c:v libx264 -preset fast
>> -crf 28 -g 25 -c:a libmp3lame -b:a 128000 -threads 4 -af volume=2.5 -vf
>> scale='352:trunc(ow/((1/sar)*dar)/2)*2',fps='fps= 20',setsar='1/1'
>> -profile:a aac_he_v2 -strict -2 -y /home/mike/testopen.mp4";
>> use Text::ParseWords;
>> @args = quotewords('\s+', "'", $str);
>>
>> use IPC::Open3;
>>
>> local(*HIS_IN, *HIS_OUT, *ERR);
>> my $cmd='ffmpeg';
>> my $pid=open3(undef, undef, *ERR,$cmd, @args) or die print "$!";
>> my $line;
>>
>> while (sysread ERR, $line, 256){
>> print $line;
>> }
>> waitpid($pid, 0);
>>
>> However the output is buffered for around 2 minutes at a time rather
>> immediately being printed
>>
>> Is there any way around this
>>
>
> Are you certain the buffering is in the read from ERR and not in the
> print? STDERR is not supposed to be buffered. Try adding
>
> $| = 1;
> Near the top of your program. That will turn off any buffering of the Perl
> 5 script's STDOUT.
>
> By default, Perl 5 will buffer STDOUT if it isn't writing to a
> pseudoterminal (eg if you are piping the output of the Perl 5 script to
> something else like tee.)
>
>
>
