G'day Striker,

You asked a very similar question (with respect to running consecutive system commands requiring some delay between them) last week: "Running 'top' command (of linux) for few minutes and then come out of system command (of perl)".

You received several responses but replied to none of them. Why was that? Did you try any of the suggested solutions? Were any of these useful to you? For those that weren't useful, in what way were they lacking?

"When I am running this command directly from shell its working fine all the processes are going on one after one."

If you can get the result you want directly from the shell, then put whatever commands you are using (from the shell) in a single shell script. Your Perl script will then just need something like:

system 'combined_shell_commands.sh';
[download]

I suspect there's more to this than you're telling us: possibly related to your CGI code or how you envisage users interacting with your "web UI". The guidelines in "How do I post a question effectively?" may help to improve your question such that we are better able to help you.