The command line tool "a2dismod" is a utility used in Linux systems. It stands for "Apache 2 Disable Module" and is typically found in Apache HTTP Server installations. It allows users to disable specific Apache modules from being loaded or used by the server. Modules in Apache provide additional functionality, such as handling specific file formats or enabling certain features. Using "a2dismod" requires administrative privileges, as it modifies the server's configuration files. Modules that are disabled with this tool will no longer be loaded upon server restart. The tool is often used when troubleshooting or securing an Apache server by disabling unnecessary or vulnerable modules. It provides an easy way to manage modules without manually editing the Apache configuration files. Using "a2dismod" followed by the module name as an argument will disable that specific module. After running the command, it is necessary to restart the Apache server for the changes to take effect.