ifchanged

Conditionally run a command if watched files have changed, for instance:

ifchanged yarn build

Running the above multiple times will only result in executing 'yarn build' if a source file has changed since last run, otherwise it is a noop.

To specify which files to watch:

ifchanged --watch="src/**/*.js"

If multiple steps depend on whether the files have changed:

 ifchanged --step=build yarn build
 ifchanged --step=build:docs yarn build:docs

To provide flags to the command, use '--' to separate them from flags to ifchanged:

ifchanged --step=build -- yarn run build --step=docs

Options:

--help         Show help                                             [boolean]

--version      Show version number                                   [boolean]

--watch, -w    Pattern to watch for changes using glob syntax.
     [default: ["src/**/*.js","tests/**/*.js","node_modules/**/package.json"]]

--rootDir, -r  Root directory to watch.
                                     [default: "/home/mike/Private/ifchanged"]

--cache, -c    Path to save internal ifchanged data to.
                    [default: "/home/mike/Private/ifchanged/.ifchanged_cache"]

--step, -s     Step name. Makes it possible to run several steps when the
               watched files have changed.                            [string]

--config       Path to JSON config file
                     [default: "/home/mike/Private/ifchanged/.ifchanged.json"]

CAVEATS

Watching different file sets

Providing different '--watch' settings between runs won't work as expected unless a different '--cache' is provided as well:

ifchanged --watch=src/*.js yarn build
ifchanged --watch=docs/*.mdx yarn build:docs

The above will not work since the same cache is being used to watch two different sets of files. To get the expected result, provide a different cache to at least one of the calls:

ifchanged --watch=src/*.js yarn build
ifchanged --watch=docs/*.mdx --cache=.ifchanged-docs yarn build:docs

Sub-second changes

To optimize for performance, ifchanged only uses file modification times and sizes to check if a new run is required. Since mtime only has a resolution of seconds, ifchange can't detect changes where it is being run with a second or less between each run.

Developing

Download and run tests

git clone [email protected]:karnov/ifchanged
cd ifchanged
yarn
yarn test

Publishing

yarn publish

Remember to log in first. If publishing fails, make sure that you have access to the karnov organization at npmjs.com.

Reporting bugs

https://github.com/karnov/ifchanged/issues

Author

Michael Zedeler [email protected].

Copyright and license

Copyright Karnov Group A/S 2018, licensed under MIT license.