How to Use the Command 'Emacs' (with Examples)

Emacs is a highly versatile, extensible, and customizable text editor that allows users to perform a wide range of tasks, from simple text editing to complex programming development. Known for its self-documenting and real-time capabilities, Emacs offers flexibility like no other text editor. It is particularly beneficial for programmers and avid computer users who thrive on keyboard shortcuts and need a powerful tool to manipulate text and code efficiently. Emacs is available not only in graphical environments but also in terminal mode, giving it the added advantage of being usable across various platforms and environments.

Start Emacs and Open a File

Code:

emacs path/to/file

Motivation for the use case:

Opening a file in Emacs is a fundamental operation, similar to launching any application to begin work on a document or project. This capability is essential for users who need to edit, view, or write content in a file. Emacs’s ability to open files from the command line enhances its utility and convenience, especially for users working in a terminal or script-driven environment.

Explanation:

• emacs: This is the command to start the Emacs editor.
• path/to/file: This argument specifies the path to the file you want to open. It could be a text file, a code file, or any other file that you can edit.

Example Output:

Opening a file will bring up the Emacs interface with the specified file loaded, ready for editing. If the file does not exist, Emacs will open a new buffer for creating a new file.

Open a File at a Specified Line Number

Code:

emacs +line_number path/to/file

Motivation for the use case:

Jumping directly to a specific line number is a valuable time-saver for developers and writers who know exactly where they need to begin their edits or inspections in large documents or code files. This feature allows users to directly navigate to the point of interest without scrolling through potentially thousands of lines, making the editing process efficient and focused.

Explanation:

• emacs: Launches the Emacs editor.
• +line_number: This option allows you to specify the line number where you want the cursor to be placed upon opening the file.
• path/to/file: Indicates the location of the file you wish to open.

Example Output:

Upon execution, the file opens in Emacs, and the cursor is positioned at the start of the specified line number, enabling immediate interaction with the target section of the text or code.

Run an Emacs Lisp File as a Script

Code:

emacs --script path/to/file.el

Motivation for the use case:

Running an Emacs Lisp file as a script is particularly useful for automating tasks or implementing custom functionalities that can be executed directly through the Emacs environment. This use case showcases Emacs’s capability as more than just a text editor — it is a platform for development and automation using Lisp, offering robust scripting functionality.

Explanation:

• emacs: Starts Emacs.
• --script: This option tells Emacs to run the specified file as a script, executing the Elisp code contained within.
• path/to/file.el: Specifies the path to the Emacs Lisp script file you wish to execute.

Example Output:

The script executes in the terminal, and any output generated by the Lisp code will display in the console, rather than in the Emacs interface.

Start Emacs in Console Mode

Code:

emacs --no-window-system

Motivation for the use case:

Starting Emacs in console mode is indispensable for users who prefer or are required to work in environments without a graphical user interface (GUI). This scenario might include accessing servers remotely or working on systems configured without GUI capabilities, yet still requiring the rich functionality of Emacs.

Explanation:

• emacs: Initiates Emacs.
• --no-window-system: This option forces Emacs to run in the terminal, without launching a GUI. It enables operations in a purely text-based environment.

Example Output:

Emacs runs within the terminal, offering a text-based interface that resembles the GUI version but is fully operable via keyboard commands and shortcuts.

Start an Emacs Server in the Background

Code:

emacs --daemon

Motivation for the use case:

An Emacs server running in the background provides a persistent editing session, allowing multiple Emacs client instances to connect and share the same environment. This is advantageous for users who want fast startup times and access to their configured environment across different sessions without reloading Emacs each time.

Explanation:

• emacs: Launches the Emacs application.
• --daemon: This option starts Emacs as a background server process, enabling connections from emacsclient.

Example Output:

No immediate visual output in the terminal as Emacs starts as a background process. Users can connect to this server with emacsclient, experiencing quick load times and access to the persistent session.

Stop a Running Emacs Server

Code:

emacsclient --eval '(save-buffers-kill-emacs)'

Motivation for the use case:

Stopping a running Emacs server is necessary when you want to close the server and all connected clients safely and securely, particularly after ensuring that all data has been saved. This command is critical in environments where you have multiple clients running and need to maintain data integrity before shutdown.

Explanation:

• emacsclient: Connects to the running Emacs server.
• --eval '(save-buffers-kill-emacs)': An Emacs Lisp command that prompts the server to save all buffers and then exit, requiring confirmation for any unsaved changes.

Example Output:

A series of prompts in Emacs for any unsaved work, asking for user confirmation to save or discard changes, followed by successfully shutting down the server.

Save a File in Emacs

Code:

<Ctrl> + X, <Ctrl> + S

Motivation for the use case:

Saving a file is a fundamental operation in text editing and software development, crucial for preserving the work done in Emacs. Regular saves reduce the risk of data loss and maintain a history of changes made during editing sessions, fostering efficient project management and version control.

Explanation:

• <Ctrl> + X: This keyboard command is the prefix for many commands in Emacs.
• <Ctrl> + S: This combination following <Ctrl> + X ensures the active buffer or file is saved.

Example Output:

The status bar confirms that the current buffer has been saved, showing any updates on file version details, such as timestamp or version number.

Quit Emacs

Code:

<Ctrl> + X, <Ctrl> + C

Motivation for the use case:

Efficiently quitting an application is as important as starting one, as it ensures a clean exit, closing all active files, and processes, and saving or discarding changes as necessary. Emphasizing proper shutdown techniques preserves system resources and minimizes the risk of data corruption.

Explanation:

• <Ctrl> + X: The prefix that begins many Emacs commands.
• <Ctrl> + C: Completes the quit command, prompting the user to save unsaved changes before closing.

Example Output:

Confirmation prompts for saving files with unsaved changes, followed by Emacs closing and returning the user to the original terminal or desktop environment.

Conclusion:

Emacs serves as both a powerful text editor and a development environment, offering users a versatile toolset for various tasks. With the ability to operate both in GUI and console modes, connect to persistent sessions, run scripts, and more, Emacs remains an invaluable tool for developers and power users alike. By understanding and utilizing these use cases, users can maximize their productivity and tailor Emacs to their unique needs.