deallocvt

deallocvt [N]

[N]
    An optional integer representing the virtual console number to deallocate. If this argument is omitted, deallocvt will attempt to deallocate all virtual consoles that are currently unused.

deallocvt is a utility designed for Linux systems to deallocate or free up resources associated with unused virtual consoles (VTs). When a virtual console is no longer active – for instance, after a text-mode login session has concluded, or a graphical environment running on a specific VT has exited – its allocated memory and other resources might still be held by the kernel. This command allows a system administrator or a privileged user to reclaim these resources, thereby reducing the system's memory footprint and improving overall resource efficiency.

It is particularly useful in environments where many virtual consoles are created and potentially left idle, or in embedded systems where resource management is critical. When invoked without arguments, deallocvt attempts to deallocate all currently unused virtual consoles. If a specific virtual console number (N) is provided as an argument, it will attempt to deallocate only that particular VT, provided it is not in use. Successful execution typically requires root privileges.

• This command requires superuser (root) privileges to execute successfully, as it modifies kernel-level resources.
• Care must be taken not to deallocate an actively used virtual console, as this could lead to system instability, application crashes, or data loss for processes running on that VT.
• The effectiveness of deallocvt can depend on the Linux kernel version and the specific implementation of virtual console management.
• It is primarily intended for cleaning up VTs that have genuinely become idle and are no longer needed.

To execute deallocvt, you must have superuser privileges. Attempting to run it as a regular user will result in a 'Permission denied' error, as it directly interacts with kernel-level console drivers to free up resources.

deallocvt is most commonly invoked in system shutdown scripts to ensure a clean system state, or as part of a cleanup routine when users log out from a text-mode console, or when a graphical session running on a specific VT terminates. Its purpose is to reclaim system memory and resources efficiently.

deallocvt is a component of the kbd (keyboard and console tools) package, which provides a suite of utilities for managing the Linux console. These tools have been fundamental to the Linux text-mode environment since its early development. The inclusion of deallocvt specifically addresses the need for efficient resource management of virtual terminals, a core feature allowing multiple independent text sessions. Its development has been driven by the ongoing efforts to optimize system resource usage and ensure a robust console experience, allowing VTs to gracefully release their allocated resources once they are no longer required.

chvt(1), openvt(1), vc(4), setvtrgb(1), resizecons(8), kbd(7)