**Linux File Descriptor Usage** is a Checkmk plugin for monitoring system-wide Linux file descriptor usage through `/proc/sys/fs/file-nr`. It reports: * Allocated file descriptors * Unused file descriptors * Maximum file descriptors * Percentage used Default thresholds are **WARN at 80%** and **CRIT at 90%**. Requires **Checkmk 2.5.x** and the Checkmk Agent. For Linux server administration and support, see [Server Management Services](https://iserversupport.com/server-management-services/).