How to watch file changes on Mac OSX using FSWatch?

Using FSWatch on Mac OSX to monitor file changes is an effective method for tracking filesystem activity, particularly useful for developers and system administrators. Below are the steps and examples for using FSWatch to monitor file changes:

Step 1: Installing FSWatch

First, ensure FSWatch is installed on your Mac. FSWatch can be installed via Homebrew; if you haven't installed Homebrew yet, obtain the installation instructions from its official website. After installing Homebrew, open the Terminal and enter the following command to install FSWatch:

bash
brew install fswatch

Step 2: Monitoring Specific Directories or Files

After installation, begin using FSWatch to monitor specific directories or files. For example, to monitor the directory at /path/to/my/directory, enter the following command in the Terminal:

bash
fswatch /path/to/my/directory

This command monitors any changes to all files and subdirectories within the specified directory and displays change events in real-time in the Terminal.

Step 3: Advanced Usage and Options

FSWatch provides various options to customize your file monitoring behavior. For instance, use the -o option to output only the total number of events, rather than details for each event:

bash
fswatch -o /path/to/my/directory

Additionally, if you're only interested in certain file types, such as monitoring all .txt files, use the following command:

bash
fswatch -e '.*' -i '\.txt$' /path/to/my/directory

Here, -e '.*' indicates excluding all files, and -i '\.txt$' indicates including only files ending with .txt.

Example: Using FSWatch to Trigger Scripts

Combine FSWatch with scripts to automate responses to file changes. For example, whenever files in the /path/to/my/directory directory are modified, automatically execute the script script.sh:

bash
fswatch -o /path/to/my/directory | xargs -n1 /path/to/script.sh

Each time a file change occurs within the directory, fswatch generates output, which xargs receives and uses as parameters to execute the script.sh script.

Conclusion

FSWatch is a powerful tool that helps you monitor filesystem changes in real-time on Mac OSX. By following the steps and examples above, you can customize FSWatch's usage according to your needs, whether for simple monitoring or integration with other scripts, FSWatch provides flexible solutions.