Compatibility With fswatch 0.x

The previous major version of fswatch (v. 0.x) allowed users to run a command whenever a set of changes was detected with the following syntax:

$ fswatch path program

Starting with fswatch v. 1.x this behaviour is no longer supported. The rationale behind this decision includes:

• The old version only allows watching one path.
• The command to execute was passed as last argument, alongside the path to watch, making it difficult to extend the program functionality to add multiple path support
• The old version forks and executes /bin/bash, which is neither portable, nor guaranteed to succeed, nor desirable by users of other shells.
• No information about the change events is passed to the forked process.

To solve the aforementioned issues and keep fswatch consistent with common UNIX practices, the behaviour has changed and fswatch now prints event records to the standard output that users can process further by piping the output of fswatch to other programs.

To fully support the old use, the -o/--one-per-batch option was added in v. 1.3.3. When specified, fswatch will only dump 1 event to standard output which can be used to trigger another program:

$ fswatch -o path | xargs -n1 program

In this case, program will receive the number of change events as first argument. If no argument should be passed to program, then the following command could be used:

$ fswatch -o path | xargs -n1 -I{} program

Although we encourage you to embrace the new fswatch behaviour and update your scripts, we provide a little wrapper called fswatch-run which is installed alongside fswatch which lets you use the legacy syntax:

$ fswatch-run path [paths] program

Under the hood, fswatch-run simply calls fswatch -o piping its output to xargs.

fswatch-run is a symbolic link to a shell-specific wrapper. Currently, ZSH and Bash scripts are provided. If no suitable shells are found in the target system, the fswatch-run symbolic link is not created.