beadm

beadm is a command-line utility used in Solaris and illumos-based operating systems for managing boot environments. A boot environment is a snapshot of the operating system, including the kernel, system files, and installed software. beadm allows users to create, clone, activate, and destroy these boot environments. This capability is crucial for system administration, particularly for performing system upgrades, testing new software, or recovering from configuration errors.

The primary function of beadm is to facilitate safe and reversible system changes. By creating a boot environment before making modifications, administrators can easily revert to a previous working state if an update or configuration change causes problems. This is achieved through the use of ZFS snapshots, as boot environments are typically stored on ZFS file systems.

Key commands include beadm create for making a new boot environment, beadm list to display existing environments, beadm activate to designate an environment as the one to boot from, and beadm destroy to remove an environment. The utility offers a robust mechanism for maintaining system stability and simplifies the process of implementing and testing changes in a production environment. Its integration with ZFS makes it a powerful tool for disaster recovery and version control of the operating system.