inotifywait with curlsftpsf mount point is not moving files as expected

Question

I'm using Ubuntu 20.04. I'm trying to run this script for inotifywait. The idea is to move files from dir to target every time a change in directory occurs; this script is a shell file that can be started automatically or manually via the command line.

#!/usr/bin/env bash
dir=/mnt/test1/test/ #ftp point of mount
target=/var/www/html/local/ #normal directory on filesystem
inotifywait -m "$dir" --format "%w%f" -e create -e moved_to |
    while read path action file; do
       mv "$file" "$target"
    done

And files to move need to have the *.txt format. inotify is watching, but when I use my ftp client to put a file in dir and wait for inotify to move it to target, nothing happens with the file.

I am using this for reference: https://unix.stackexchange.com/a/86292/425161

Answer 1

Unfortunately, the inotify API can not be used to monitor remote file systems.

From man 7 inotify:

Inotify reports only events that a user-space program triggers through the filesystem API. As a result, it does not catch remote events that occur on network filesystems. (Applications must fall back to polling the filesystem to catch such events.)

Relating questions:

• Is there a way to use inotify on remote filesystems (specifically WebDAV)?
• Monitor folders mounted via SSHFS
• How do I use inotify or named pipes over SSHFS?

That said, the script in your question would not work as expected anyway.

The idea of using "%w%f" as the format of inotifywait's output is to provide the command in the loop with the full path of files that triggered a listened-for file system event. %w expands to the path of the watched file (the $dir directory), and %f expands to the (base)name of the file that caused the event.

Thus, inotifywait is only emitting a single full path for every event it catches. On the other hand, your read command is given three variables to fill in: path, action and file. By default, read splits a read line based on the characters in IFS and assigns the resulting tokens to the names it is given as arguments: the first token to the first name, the second token to the second name, etc. (And, if there are more tokens than names after the penultimate name, all the remaining tokens are assigned to the last name).

As you can easily check, in your code the full path of any file that trigger a watched-for event is assigned to path (unless it contained blank characters):

$ inotifywait -m --format "%w%f" -e create -e moved_to /tmp/test |
  while read path action file; do
    printf 'path: "%s"; action: "%s"; file: "%s"\n' "$path" "$action" "$file"
  done
# Type "touch /tmp/test/foo" in a different terminal
path: "/tmp/test/foo"; action: ""; file: ""

Also, as pointed out in a different answer in the Q/A you inked to, you should listen for close_write events, and not for create. What you are probably looking for is:

inotifywait -m -q --format "%w%f" -e close_write -e moved_to -- "$dir" |
  while IFS= read -r src; do
    if [ "${src##*.}" = 'txt' ]; then
      mv -- "$src" "$target"
    fi
  done

-r tells read not to interpret backslash-escaped sequences. IFS= is used to prevent read from trimming blank characters from the end of file names (to handle the unlikely case of names ending with spaces or tabs).

Note that this will still fail for files whose name contains newline characters.