I little bit dated thread, but I have tried nohup and it just hangs. I reboot, login with putty from my laptop, run a raspistill from the CLI and it works just fine.
I go to my webmin (sorry... raspbian, lamp server, with webmin and samba) and try it with a cron job and not only does it NOT work, but when I putty and try again, it hangs. I tried killing, and terminating the raspistill process from webmin and rinsed/repeat. No go.
I reboot and I can CLI raspistill again, but I am still not sure what is going on here. As others have said, if the program is single use only, why does it hang instead of exiting quickly with an error? OK, it does that, but with misleading info about how my GPU doesn't have enough memory, etc. I don't even USE my GPU and have it set for ZERO memory allocated.
I apologize sincerely for my linux ignorance, if that is the cause. If it isn't, I hope it is fixed soon.
Thank you for your time!
EDIT: I just tried raspistill again and got...