Short answer: you can't. Ports below 1024 can be opened only by root. As per comment - well, you can, using CAP_NET_BIND_SERVICE, but that approach, applied to java bin will make any java program to be run with this setting, which is undesirable, if not a security risk.
The long answer: you can redirect connections on port 80 to some other port you can open as normal user.
Run as root:
# iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-port 8080
As loopback devices (like localhost) do not use the prerouting rules, if you need to use localhost, etc., add this rule as well (thanks @Francesco):
# iptables -t nat -I OUTPUT -p tcp -d 127.0.0.1 --dport 80 -j REDIRECT --to-ports 8080
NOTE: The above solution is not well suited for multi-user systems, as any user can open port 8080 (or any other high port you decide to use), thus intercepting the traffic. (Credits to CesarB).
EDIT: as per comment question - to delete the above rule:
# iptables -t nat --line-numbers -n -L
This will output something like:
Chain PREROUTING (policy ACCEPT)
num target prot opt source destination
1 REDIRECT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:8080 redir ports 8088
2 REDIRECT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:80 redir ports 8080
The rule you are interested in is nr. 2, so to delete it:
# iptables -t nat -D PREROUTING 2
The correct way to sleep in a batch file is to use the timeout command, introduced in Windows 2000.
To wait somewhere between 29 and 30 seconds:
timeout /t 30
The timeout would get interrupted if the user hits any key; however, the command also accepts the optional switch /nobreak, which effectively ignores anything the user may press, except an explicit CTRL-C:
timeout /t 30 /nobreak
Additionally, if you don't want the command to print its countdown on the screen, you can redirect its output to NUL:
timeout /t 30 /nobreak > NUL
Best Answer
I'd set up some kind of queueing service. A quick Google on "ready to use" stuff shows this:
Depending on your needs you could simply
Actually there's more to it, you could have requirements that implement a priority queue which brings up problems like starving jobs or similiar but it's not that bad to get something up and running quite fast.
If LDP as suggested by womble I'd take that. Having such a system maintained by a larger community is of course better than creating your own bugs for problems others already solved :)
Also the queuing service has the advantage of decoupling the resources from the actual number crunching. By making the jobs available over some network connection you can simply throw hardware at a (possible) scaling problem and have nearly endless scalability.