entr (event notification test runner) is a command-line utility that allows you to execute arbitrary commands whenever specified files change. It monitors a list of files and, upon detecting any modification, runs the associated command. This is particularly useful for automating development workflows like recompiling code, restarting servers, or running tests as soon as source files are updated. entr is a free and open-source tool designed to be lightweight and efficient.
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Why It’s Useful
entr automates the tedious process of manually re-running commands after every code save. For developers, this means immediate feedback on code changes, significantly boosting productivity for tasks like live reloading web servers, re-rendering documentation, or running linting checks. It integrates seamlessly into shell scripts and build processes, making it a powerful addition to any developer's toolkit. Its simplicity belies its effectiveness, allowing users to set up continuous feedback loops with minimal configuration. It’s ideal for anyone engaged in rapid iteration on code-based projects.
In everyday life
When you’d actually reach for this
You're developing a website and want the browser to automatically refresh every time you save a CSS or HTML file. You can configure `entr` to watch these files and trigger a browser refresh command, so you see your changes instantly without manual intervention.
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