Codex CLI Composer & Input Shortcuts

Start with steering, because it is the binding that most changes how the tool feels once you understand it. While the agent is running, Enter sends your message straight into the turn in progress, altering what it is doing immediately. Tab holds the message until the current turn completes, then delivers it as the next instruction. The distinction maps cleanly onto intent: 'stop, that is the wrong file' is an Enter, 'after that, update the changelog' is a Tab. Neither is destructive, but choosing wrong is frustrating in a specific way — a correction sent with Tab arrives after the mistake it was supposed to prevent. Newline insertion is Ctrl+J, and this is the single most-searched thing about Codex CLI's input handling. Shift+Enter is what almost everyone tries, and it works in some terminals and not others. The reason is not Codex: terminals differ in whether they transmit a distinguishable sequence for Shift+Enter at all, so in many of them the application receives something indistinguishable from a plain Enter and sends the message. Ctrl+J transmits an actual line-feed character that every terminal passes through identically, which is why it works everywhere. For anything longer than a few lines, Ctrl+G is the better answer than either. It hands the composer contents to whatever VISUAL or EDITOR points at — Vim, Emacs, VS Code, whatever you have configured — and takes back what you save. The composer is not a text editor and does not try to be, so a carefully-structured prompt with sections and examples is much less painful written in a real one. This is also the route to reuse: a prompt drafted in your editor can be saved before it is sent. Esc pressed twice on an empty composer reopens your previous message for editing, and continuing to press walks further back through the transcript. This is more useful than it sounds. When the agent has misread a prompt, rewording the original is often better than adding a clarification, because a clarification leaves the ambiguous instruction in the conversation where it continues to exert influence. The Up and Down arrows do something adjacent but different — they step through composer drafts you typed, restoring text and image placeholders, rather than messages you actually sent. Three prefix characters change what the composer does with what follows. Typing @ opens a fuzzy file search across the workspace; accepting a match attaches that file to the conversation, which is far more reliable than describing a path in prose and hoping the agent finds the right thing. Typing ! runs the rest of the line as a shell command on your machine, outside the sandbox, showing you the output without sending any of it to the model. And typing / opens the slash-command popup, which is where most of Codex's functionality actually lives. The ! prefix deserves a second look because both halves of its behaviour matter. Outside the sandbox means it runs with your permissions in your shell — the boundary constraining the agent does not constrain you here, so the usual care applies. Not sent to the model means checking something costs you nothing in context. A quick git log, a directory listing, a test run you want to see yourself: all free, where asking the agent to look would consume tokens and add noise to the conversation. Images round the set out. Screenshots paste directly into the composer in terminals that support it, and the -i flag attaches them at launch. For a broken UI, an error dialog, or a design you want implemented, showing is faster and less lossy than describing — and this is one of the clearer cases where the terminal interface is not the limitation it appears to be. The slash-command popup deserves a mention as an input mechanism rather than a list of features. Typing / filters as you type, so you do not need to remember exact command names — a fragment usually gets you there, and the popup shows what each one does as you scroll. In effect it is the discoverability layer a terminal application would otherwise lack, and it is the reason Codex can ship several dozen commands without a manual. Typing /help lists everything your specific binary supports, which matters because the set has grown between releases. A final observation about the composer as a whole. Almost every genuine key binding here exists because typing is happening concurrently with work, which is not a situation traditional software design has had to solve. Steering versus queueing, editing a message you already sent, attaching a file without breaking your line of thought, running a command whose output the model never sees — each of these is an answer to the same underlying question of how a person stays in control of something that is already in motion. Read that way the composer's small keymap is more coherent than it first appears.