I have a perl script that simply prints an incremented number every second: 
#!/usr/bin/perl

$FLUSH=1;

while (1) {
  print "$i\n";

  if ($FLUSH) {
    my($oldfh) = select(STDOUT);
    $| = 1;
    select($oldfh);
  }
  sleep 1;
  $i++;
}

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If I have $FLUSH set to 1 and invoke it from a bash prompt, piping the output to "more", then I see a number displayed every second.

If I don't have $FLUSH set, then if I run it with the output piped to "more", I don't see any output.

Now say for example that FLUSH is NOT set and I am unable to set FLUSH (for example if I don't have permission to modify to the program).

If I want to run the command and pipe it to "more", is there a way for me to externally set STDOUT to "autoflush" when invoking the program?

(in specific my case, I need to access another compiled executable in C that does not flush output as it is written)

In reply to can you autoflush a program in unix? by redss

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