Remove all files in *that* directory except *these* files - dangerous in remote directory?

Question

I'm writing a small bash script for deploying a bunch of files to a specific remote directory. The process is as follows:

1. Mount remote directory (sshfs)
2. Remove everything except these few files
3. Copy all the files from the local directory to the remote one.

I suddenly realized that if something went wrong mounting the remote directory, for example if I'd lost my internet connection, this script would remove everything from the directory I'm currently in! Which could easily be disastrous. So - what would the correct procedure be?

Answer 1

Since you don't provide your script I'm going to guess a little bit what it looks like. There might be several points for improvement.

The first and most important point would be to prevent accidental local access by design. So use paths to your mounted files instead of cd'ing into a directory that might not exist. Do write:

rm /mnt/everything_except_these_files

If you don't want to use /mnt as a mount point, consider creating a temporary directory using mktemp -d.

Next, and almost as important: abort your script on error. Writing set -e at the top of the script will accomplish that. If your mount fails, no other commands will be run.

To navigate around the shortcomings of set -e in certain cases, you might also consider exit'ing explicitly if an important command failed, like this

mount ... || exit 1

(thanks to tjm3772 for bringing up the issue)

You can test if a directory is actually a mount point using the mountpoint command. This will fail on a local directory.

I hope any of these suggestions might help.