open PROG,"program|" or die "Cannot fork";
while (<PROG>) {

 # do stuff...
}
[download]

see perlopentut

cdrecord seems to be buffering output
Thanks guys. Been away making supper. Now, Seems like this silly cdrecord thing is buffering the output. I tried what was suggested and noting was output until the enture cd had completed the record (which of course by that stage is way too late). So, now the question is: how do I get hold of this output without hacking cdrecord?

perl -e 'open (FD1, "/usr/bin/cdrecord -vs -dummy -eject /mnt/test/Deb
+ian/2disc.iso |");
while (<FD1>) { $_ =~ s/^M//g; print $_ if /^Track/; };
close (FD1)
[download]

My output looks like:
Track 01: 0 of 47 MB written.Track 01: 1 of 47 MB written (fifo 96%).....etc.

Thanks for the help so far.
Cheers
H

It is likely outputting something without newlines (i.e. "\r" instead of "\n"), so you could try setting your input record seperator to that, for instance: local $/ = "\r";

Also see the perlfunc section on getc for more info on input buffering.

Hope this helps,
Joost.

"What should it profit a man, if he should win a flame war, yet lose his cool?"

I'm not familiar with cdrecord, but assuming it prints stuff to standard output while it is progressing, you could pipe its output into perl like this:

print "invoking cdrecord...\n";
open CD, "cdrecord |" or die "Couldn't run cdrecord";
while(<CD>) {
    # check $_ for whatever output you're looking for
    # or just print $_;
}
close CD;
print "cdrecord finished\n";
[download]

I hope that's useful. If you can supply a bit more info about how cdrecord outputs its progress, that may help get a more precise answer.

#!/usr/bin/perl
use warnings;
use IPC::Open3;

#cdrecord sends a /r (no newline) to output status 
#so it is difficult to get output 

my $pid = open3(\*WRITE, \*READ,0,"/usr/bin/cdrecord -v -dummy -eject 
+dev=1,1,0  my.iso");
            #if \*ERROR is false, STDERR is sent to STDOUT  

while(1){

select(undef,undef,undef,.01);

 if( sysread \*READ,$output,1024 ){
     print "$output\n";
 }else{ print "finished\n"; exit; }

}
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Track 01:   89 of   97 MB written (fifo 100%) [buf  99%]  27.3x.
Track 01:   90 of   97 MB written (fifo 100%) [buf  99%]  26.5x.
Track 01:   91 of   97 MB written (fifo  98%) [buf  99%]  27.3x.
Track 01:   92 of   97 MB written (fifo 100%) [buf  99%]  26.6x.
Track 01:   93 of   97 MB written (fifo  98%) [buf  99%]  27.4x.
Track 01:   94 of   97 MB written (fifo 100%) [buf  99%]  26.6x.
Track 01:   95 of   97 MB written (fifo 100%) [buf  99%]  27.4x.
Track 01:   96 of   97 MB written (fifo 100%) [buf  99%]  28.3x.
Track 01:   97 of   97 MB written (fifo 100%) [buf  99%]  27.5x.

Track 01: Total bytes read/written: 102400000/102400000 (50000 sectors
+).

Writing  time:   42.959s
Average write speed  15.5x.
Min drive buffer fill was 99%
Fixating...

WARNING: Some drives don't like fixation in dummy mode.
Fixating time:   26.760s

/usr/bin/cdrecord: fifo had 1613 puts and 1613 gets.
/usr/bin/cdrecord: fifo was 0 times empty and 872 times full, min fill
+ was 85%.

finished
[download]

#!/usr/bin/perl
use warnings;
use strict;
use IPC::Open3;

my $pid = open3(\*WRITE, \*READ,0,"/usr/bin/cdrecord -v -dummy -eject 
+/mnt/my.iso");
            #if \*ERROR is false, STDERR is sent to STDOUT  

#while(1){ 

#select(undef,undef,undef,.01); 

chomp(my $output = <READ>);
print "$output\n";

#do some split and test to extract percentage 

#} 

waitpid($pid, 1);
# It is important to waitpid on your child process,   
# otherwise zombies could be created.
[download]

Thanks guys for the help.

I have tried all these solutions. None of them work. They all print the information I am wanting at the end of cutting the CD. I looked through the cdrecord code, and Jorg places a \r at the beginning of each line of output denoting how much of the cd has been cut. I tried removing those in perl, but to no avail either.
What's really strange is if I redirect the output to a file, and then tail the file simultaneously, I get the information I am after. When I look at the file with VI, I see the following type of output:

^MTrack 01 0 of 47MB^MTrack 01 1 of 47MB^MTrack 01 2 of 47MB^M.....etc....

This has the effect that each line indicating the percent of the track cut is over-written by the next line, creating that "nice" feeling of interactivity. I just find it's making my life hell.

Also not sure that I fully understand how it can well be appending to a file on redirecting output from cdrecord, but not giving me the output when I pop the same in a perl script.
Cheerio
Hambo

There is some information on dealing with these situations in "perldoc -q filehandle", about using sysread and ioctl. I'll try to get an example that works with cdrecord and post it later.

---

I'm not really a human, but I play one on earth. flash japh