CLAUDE_CODE_NONBLOCKING_STDOUT

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_CODE_NONBLOCKING_STDOUT is a Claude Code environment variable. Added between v2.1.252 and v2.1.266 and still present in v2.1.294. It is listed in the official reference.

Status	Present in v2.1.294
Added	Added between v2.1.252 and v2.1.266
Category	Other
Official docs	Listed

How to set it

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

export CLAUDE_CODE_NONBLOCKING_STDOUT=<value>
claude

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

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

Related variables

CLAUDE_CODE_TEE_SDK_STDOUT
ANTHROPIC_BETAS: Comma-separated beta feature headers.
ANTHROPIC_CUSTOM_HEADERS: Custom HTTP headers (newline-separated Key: Value).
ANTHROPIC_FEDERATION_RULE_ID
ANTHROPIC_ORGANIZATION_ID
ANTHROPIC_WORKSPACE_ID
BETA_TRACING_ENDPOINT: Custom endpoint for beta tracing.
CLAUDE_AFK_COUNTDOWN_MS

Frequently asked questions

Which Claude Code version has CLAUDE_CODE_NONBLOCKING_STDOUT?

Added between v2.1.252 and v2.1.266 and still present in v2.1.294.

How do I set CLAUDE_CODE_NONBLOCKING_STDOUT?

Export it before starting Claude Code (export CLAUDE_CODE_NONBLOCKING_STDOUT=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.