Mac OSX Terminal : Prevent your mac from falling asleep

caffeinate -i -s /bin/ssh ...

Explanation:

-i - Prevent idle sleep.

-s - Prevent system sleep (entirely, even if you close the lid). Note: it only works while on AC power.

/bin/ssh - Just keep writing the command you want to execute. Using ssh directly instead of/bin/ssh should also work.

Results: Your system will not sleep as long as the ssh command is running.