CLAUDE_CODE_TMUX_TRUECOLOR

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_CODE_TMUX_TRUECOLOR is a Claude Code environment variable: Controls truecolor (24-bit) rendering when running inside tmux. Tmux has historically been tricky with truecolor support — it requires both the terminal emulator and tmux itself to agree on capabilities. Added between v2.1.79 and v2.1.83 and still present in v2.1.294. It is listed in the official reference.

Status	Present in v2.1.294
Added	Added between v2.1.79 and v2.1.83
Category	Terminal and UI
Official docs	Listed

How to set it

For one session, export it in the shell that starts Claude Code:

export CLAUDE_CODE_TMUX_TRUECOLOR=<value>
claude

To apply it to every session, add it to the env object of a settings file:

// ~/.claude/settings.json
{
  "env": {
    "CLAUDE_CODE_TMUX_TRUECOLOR": "<value>"
  }
}

Release notes that mention it

Claude Code v2.1.83 — 8 New Environment Variables: Security Hardening and the 40-Fix Mega Release

Related variables

CLAUDE_CODE_TMUX_PREFIX: Tmux prefix key shown in detach instructions.
CLAUDE_CODE_TMUX_PREFIX_CONFLICTS: Show prefix twice when key conflicts in tmux.
CLAUDE_CODE_TMUX_SESSION: Tmux session name shown in UI header.
CLAUDE_AX_PREPARK_MS
CLAUDE_AX_SCREEN_READER
CLAUDE_AX_STARTUP_QUIET_MS: Startup quiet window (milliseconds) for screen-reader mode.
CLAUDE_CODE_ACCESSIBILITY: Enable accessibility mode; disables cursor hiding.
CLAUDE_CODE_ALT_SCREEN_FULL_REPAINT

Frequently asked questions

What does CLAUDE_CODE_TMUX_TRUECOLOR do?

Controls truecolor (24-bit) rendering when running inside tmux. Tmux has historically been tricky with truecolor support — it requires both the terminal emulator and tmux itself to agree on capabilities.

Which Claude Code version has CLAUDE_CODE_TMUX_TRUECOLOR?

Added between v2.1.79 and v2.1.83 and still present in v2.1.294.

How do I set CLAUDE_CODE_TMUX_TRUECOLOR?

Export it before starting Claude Code (export CLAUDE_CODE_TMUX_TRUECOLOR=value), or add it to the "env" object in ~/.claude/settings.json to apply it to every session.

All variables, searchable: Claude Code environment variables.