How did I came up with this? simply because, I needed to inform marketing team whenever there is a new csv uploaded. So initially we used to watch directory on daily bases whether new CSV uploaded. That was super boring so I thought to automate this process.

I found out that inotify can help me to achieve this.

So, let’s do it.

Install inotify

This library provides a thin layer on top of the basic inotify interface. The primary use is to easily set up watches on files, potentially many files at once, and read events without having to deal with low-level I/O. There are also several utility functions for inotify-related string formatting.

Debian/Ubuntu

inotify-tools is available in Debian’s official repositories. You can install it by:

sudo apt-get install inotify-tools
Ryan Niebur is the Debian package maintainer.

CentOS/RHEL 7

inotify-tools is available through the EPEL repository. Install EPEL :

yum install -y epel-release && yum update

Then install package:

yum install inotify-tools
# In case of CentOS-7
yum --enablerepo=epel install inotify-tools

To install on any other linux distro follow this url

Write a shell script

In order to watch a directory we’ll write a shell script which will sends notifications whenever there is new file uploaded to directory.

sudo nano watchdirectory.sh

Above script will create a file in /home/ubuntu/watchdirectory.sh

inotifywait -m /tmp/test -e create -e moved_to |
    while read path action file; do
    	echo 'The file $file appeared in directory $path via $action'
    done

Test the bash script.

sh /home/ubuntu/watchdirectory.sh
# output
Setting up watches.
Watches established.

Keep the command running. Open new terminal and SSH to your host then create a file /tmp/test/test.txt You’ll receive message in a terminal where we execute bash script. Output will be

The file test.txt appeared in directory /tmp/test/ via CREATE

Sending slack notifications

Get your slack API credentials, We’ll need slack webhook URL and a slack channel name. Which you’ll get it from here.

To test your slack endpoint run following command in your terminal, Make sure you replace the required attribute.

curl -X POST \
  --data-urlencode "payload={'channel': '#your_channel_name', 'username': 'newfilebot', 'text': 'This is a test call', 'icon_emoji': ':ghost:'}" \
  https://hooks.slack.com/services/XXXXXXXXX/XXXXXXXXX/XXXXXXXXXXXXXXXXXXXXXXXX

You will get slack notification in #your_channel_name channel.

Now let’s modify bash script

We’ll add slack notification snippet in /home/ubuntu/watchdirectory.sh bash script.

inotifywait -m /tmp/test -e create -e moved_to |
    while read path action file; do
    	curl -X POST \
    		--data-urlencode "payload={'channel': '#your_channel_name', 'username': 'newfilebot', 'text': 'This is a test call', 'icon_emoji': ':ghost:'}" \
    		https://hooks.slack.com/services/XXXXXXXXX/XXXXXXXXX/XXXXXXXXXXXXXXXXXXXXXXXX
    done

Re-run the bash script you’ll get slack notification.

sh /home/ubuntu/watchdirectory.sh
# output
Setting up watches.
Watches established.

Keep the command running. Open new terminal and SSH to your host then create a file /tmp/test/test2.txt You’ll get notification in your slack.

The file test2.txt appeared in directory /tmp/test/ via CREATE

Running script in background

So above script will needs to run in background to watch directory continuously. In order to achieve that I’ll use the nohup.

Run script using nohup

nohup bash /home/ubuntu/watchdirectory.sh </dev/null >/dev/null 2>&1 &

This will keep script running in background and trigger the notification whenever there is a new file in the /tmp/test directory.

We done here. I’ve used slack because it was a requirement for me. But in your case you can modify based on your need, It could be email notification, sms or any api call. Possibilities are endless.

Cheers!!