Pleasure for my english. I'm trying to use crontab utility to exec a programm a.out. But something goes wrong and I receive the mail a.out not found. The path is correct. When I use crontab to launch a simple command as echo, this operation goes ok. Perhaps I have to use some special procedure to exec a file .out with crontab? Thanks for your time.

Make sure a.out is executable, you can set this with "chmod +x /path/to/a.out"