CtrlB

Ctrlb, written as Ctrl+B, is a keyboard input that combines the Control key with the letter B. It does not have a single universal function; its meaning depends on the software and context. In general, Ctrlb is one of several common control-key shortcuts that vary by application.

In word processing and text editors, Ctrl+B is commonly used to toggle bold formatting. When text is selected, pressing Ctrl+B typically applies bold; in some editors, typing with the shortcut active will continue bold until deactivated. This usage is widespread in many rich-text editors and integrated development environments that adopt common shortcut conventions.

In terminal multiplexers, Ctrl+B serves as a command prefix. The most notable example is tmux, where Ctrl+B begins a command sequence that is followed by another key to perform actions (for instance, Ctrl+B followed by d detaches the session). This prefix model allows multiple commands to be issued within a single session.

In GNU Readline and many Unix-like shells that use emacs-style keybindings, Ctrl+B moves the cursor backward one character. It is part of a broader set of navigation shortcuts that resemble the standard left/right cursor movement controls.

In Vim, Ctrl+B scrolls the screen upward by one page in Normal mode, functioning as a navigation command distinct from the text-editing shortcuts.

Because Ctrl+B has multiple uses, its function should be inferred from the context and application. Users should consult the specific program’s help or documentation to confirm the exact binding.