If you regularly edit a certain group of files, you can define them as a fileset. This lets you perform certain operations, such as visiting, query-replace, and shell commands on all the files at once. To make use of filesets, you must first add the expression (filesets-init) to your init file (Init File). This adds a Filesets sub-menu to the menu bar's File menu. The simplest way to define a fileset is by adding files to it one at a time. To add a file to fileset name, visit the file and type M-x filesets-add-buffer =RET name RET=. If there is no fileset name, this creates a new one, which initially contains only the current file. The command M-x filesets-remove-buffer removes the current file from a fileset. You can also edit the list of filesets directly, with M-x filesets-edit (or by choosing Edit Filesets from the Filesets menu). The editing is performed in a Customize buffer (Easy Customization). Normally, a fileset is a simple list of files, but you can also define a fileset as a regular expression matching file names. Some examples of these more complicated filesets are shown in the Customize buffer. Remember to select Save for future sessions if you want to use the same filesets in future Emacs sessions. You can use the command M-x filesets-open to visit all the files in a fileset, and M-x filesets-close to close them. Use M-x filesets-run-cmd to run a shell command on all the files in a fileset. These commands are also available from the Filesets menu, where each existing fileset is represented by a submenu. Version Control, for a different concept of filesets: groups of files bundled together for version control operations. Filesets of that type are unnamed, and do not persist across Emacs sessions.