# filename-reserved-regex > Regular expression for matching reserved filename characters On Unix-like systems `/` is reserved and [`<>:"/\|?*`](https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file#naming-conventions) as well as non-printable characters `\u0000-\u001F` on Windows. ## Install ``` $ npm install filename-reserved-regex ``` ## Usage ```js import filenameReservedRegex, {windowsReservedNameRegex} from 'filename-reserved-regex'; filenameReservedRegex().test('foo/bar'); //=> true filenameReservedRegex().test('foo-bar'); //=> false 'foo/bar'.replace(filenameReservedRegex(), '!'); //=> 'foo!bar' windowsReservedNameRegex().test('aux'); //=> true ``` ## API ### filenameReservedRegex() Returns a regex that matches all invalid characters. ### windowsReservedNameRegex() Returns an exact-match case-insensitive regex that matches invalid Windows filenames. These include `CON`, `PRN`, `AUX`, `NUL`, `COM1`, `COM2`, `COM3`, `COM4`, `COM5`, `COM6`, `COM7`, `COM8`, `COM9`, `LPT1`, `LPT2`, `LPT3`, `LPT4`, `LPT5`, `LPT6`, `LPT7`, `LPT8` and `LPT9`.