Everyone is mentioning error control for shell scripts or "don't use shell scripts", but neither of those are the solution to this problem. The solution to this

Everyone is mentioning error control for shell scripts or "don't use shell scripts", but neither of those are the solution to this problem. The solution to this problem is correctly implementing atomic deployment, which is important for any system using any programming language. What I like to do is have two directories I ping pong between when deploying, and a `cur` symlink that points to the current version. The symlink is atomically replaced (new symlink and rename it over) whenever the deploy process completes. Any software/scripts using that tree will be written to first chdir() in, which will resolve the symlink at that time, and thus won't be affected by the deploy (at least as long as you don't do it twice in a row; if that is a concern due to long running processes, you could use timestamped directories instead and a garbage collection process that cleans stuff up once it is certain there are no users left).