OS X: how to keep the computer from sleeping during a http connection

Question

An application I use downloads data from a specific server, and I need it to sleep after the download has finished and the socket is closed.

However downloads take place at random days, the app that downloads checks for updates and only downloads if there is one

Proto Recv-Q Send-Q  Local Address          Foreign Address        (state)    
tcp4       0      0  192.168.1.29.51005     8.8.8.8.80      ESTABLISHED

Pretend 8.8.8.8 is server where data is downloaded from.

Is there a way to prevent the computer sleeping while there is HTTP session to a specific server in progress?

Now please excuse my pseduo script, but it's the best way I could try

netstat -anp tcp 
IF Foreign Address = 8.8.8.8 & state = ESTABLISHED
then
    WAIT AND CHECK IN 10 MINUTES
else
    pmset sleepnow
fi

Answer 1

Since Mac OS X 10.8, you should be able to use the caffeinate(8) command.

Try caffeinate -s curl http://example.com/some/url.

Answer 2

if you convert your psudo code to sh, here is a test for your if

netstat -anp|grep EST|sed 's/^..p6\? \+[^ ]\+ \+[^ ]\+ \+[^ ]\+ \+\([^ ]\+\) \+.*$/\1/'|grep -q 8.8.8.8 && echo connected

so you need a while loop and a sleep 10m and a pmset 0 but as my osx box is in storage it would be a good idea to check my re.