my $pid = open(SFTP, '|-', "sftp $hostname > /tmp/_sftplog.txt");

print SFTP "some commands";
		
close (SFTP);

my $pidflag;
		
do {
  system('sleep 5');
  $pidflag = `ps -a \| grep -c \' $pid \'`;
  chomp($pidflag);  
} while ($pidflag);