[SOLVED] Perl - How to suppress output from a forked child process

Perl - How to suppress output from a forked child process

I have a perl script which has to make a call to tar within an exec.

exec("tar zcf /tmp/mytarball.gz directoryToTarBall > /dev/null 2>&1" or die ("$!")

This is a child process which I have forked and in the meantime, I'm monitoring the progress of the tar by writing a full stop to STDOUT. The problem I have is that I don't want tar to be verbose when creating the tarball - i dont want output to be echoed to stdout....I just want the progress counter (the full stops) echoing back to screen. I thought I could pass a >/dev/null 2>&1 within the exec command but that didn't work.

Any ideas greatly received. Thanks and regards

Solution

Use the exec LIST form to avoid surprises due to shell quoting. This also requires performing the redirection that the shell would do for you.

use 5.10.0;  # //

my $pid = fork // die "$0: fork: $!";   # / fix Stack Overflow highlighting
if ($pid) {
  waitpid $pid, 0 or die "$0: waitpid: $!";
  warn "$0: child exited abnormally" if $?;
  print ".\n";  # done!
}
else {
  open STDOUT, ">",  "/dev/null" or die "$0: open: $!";
  open STDERR, ">&", \*STDOUT    or exit 1;
  exec "tar", "zcf", "/tmp/mytarball.gz", "directoryToTarBall";
  exit 1;
}