use IPC::Open3;

# Open output in parent
open OUTFILE, '>', '/where/to/put/output' or do {
  die "error opening output file: $!";
};
# Spawn child inheriting parent input and redirecting all output
my $pid = open3(
  '<&STDIN', '>&OUTFILE', undef,
  $impKorr, -cfgfile => $cfgfile, -dbuser => $USER, -dbpassword => $PWD
) or do {
  die "error spawning external process: $!";
};
# Close output in parent
close OUTFILE or do {
  warn "error closing output file: $!";
};
# Reap child and determine return code
my $rc = (waitpid($pid, 0) == $pid ? $? : undef);