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Environment variables

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Environment variables

Complete reference for environment variables that control Claude Code behavior.

Claude Code supports the following environment variables to control its behavior. Set them in your shell before launching claude, or configure them in settings.json under the env key to apply them to every session or roll them out across your team.

Variable Purpose
ANTHROPIC_API_KEY API key sent as X-Api-Key header. When set, this key is used instead of your Claude Pro, Max, Team, or Enterprise subscription even if you are logged in. In non-interactive mode (-p), the key is always used when present. In interactive mode, you are prompted to approve the key once before it overrides your subscription. To use your subscription instead, run unset ANTHROPIC_API_KEY
ANTHROPIC_AUTH_TOKEN Custom value for the Authorization header (the value you set here will be prefixed with Bearer)
ANTHROPIC_BASE_URL Override the API endpoint to route requests through a proxy or gateway. When set to a non-first-party host, MCP tool search is disabled by default. Set ENABLE_TOOL_SEARCH=true if your proxy forwards tool_reference blocks
ANTHROPIC_BEDROCK_BASE_URL Override the Bedrock endpoint URL. Use for custom Bedrock endpoints or when routing through an LLM gateway. See Amazon Bedrock
ANTHROPIC_BEDROCK_MANTLE_BASE_URL Override the Bedrock Mantle endpoint URL. See Mantle endpoint
ANTHROPIC_BETAS Comma-separated list of additional anthropic-beta header values to include in API requests. Claude Code already sends the beta headers it needs; use this to opt into an Anthropic API beta before Claude Code adds native support. Unlike the --betas flag, which requires API key authentication, this variable works with all auth methods including Claude.ai subscription
ANTHROPIC_CUSTOM_HEADERS Custom headers to add to requests (Name: Value format, newline-separated for multiple headers)
ANTHROPIC_CUSTOM_MODEL_OPTION Model ID to add as a custom entry in the /model picker. Use this to make a non-standard or gateway-specific model selectable without replacing built-in aliases. See Model configuration
ANTHROPIC_CUSTOM_MODEL_OPTION_DESCRIPTION Display description for the custom model entry in the /model picker. Defaults to Custom model (<model-id>) when not set
ANTHROPIC_CUSTOM_MODEL_OPTION_NAME Display name for the custom model entry in the /model picker. Defaults to the model ID when not set
ANTHROPIC_CUSTOM_MODEL_OPTION_SUPPORTED_CAPABILITIES See Model configuration
ANTHROPIC_DEFAULT_HAIKU_MODEL See Model configuration
ANTHROPIC_DEFAULT_HAIKU_MODEL_DESCRIPTION See Model configuration
ANTHROPIC_DEFAULT_HAIKU_MODEL_NAME See Model configuration
ANTHROPIC_DEFAULT_HAIKU_MODEL_SUPPORTED_CAPABILITIES See Model configuration
ANTHROPIC_DEFAULT_OPUS_MODEL See Model configuration
ANTHROPIC_DEFAULT_OPUS_MODEL_DESCRIPTION See Model configuration
ANTHROPIC_DEFAULT_OPUS_MODEL_NAME See Model configuration
ANTHROPIC_DEFAULT_OPUS_MODEL_SUPPORTED_CAPABILITIES See Model configuration
ANTHROPIC_DEFAULT_SONNET_MODEL See Model configuration
ANTHROPIC_DEFAULT_SONNET_MODEL_DESCRIPTION See Model configuration
ANTHROPIC_DEFAULT_SONNET_MODEL_NAME See Model configuration
ANTHROPIC_DEFAULT_SONNET_MODEL_SUPPORTED_CAPABILITIES See Model configuration
ANTHROPIC_FOUNDRY_API_KEY API key for Microsoft Foundry authentication (see Microsoft Foundry)
ANTHROPIC_FOUNDRY_BASE_URL Full base URL for the Foundry resource (for example, https://my-resource.services.ai.azure.com/anthropic). Alternative to ANTHROPIC_FOUNDRY_RESOURCE (see Microsoft Foundry)
ANTHROPIC_FOUNDRY_RESOURCE Foundry resource name (for example, my-resource). Required if ANTHROPIC_FOUNDRY_BASE_URL is not set (see Microsoft Foundry)
ANTHROPIC_MODEL Name of the model setting to use (see Model Configuration)
ANTHROPIC_SMALL_FAST_MODEL [DEPRECATED] Name of Haiku-class model for background tasks
ANTHROPIC_SMALL_FAST_MODEL_AWS_REGION Override AWS region for the Haiku-class model when using Bedrock or Bedrock Mantle
ANTHROPIC_VERTEX_BASE_URL Override the Vertex AI endpoint URL. Use for custom Vertex endpoints or when routing through an LLM gateway. See Google Vertex AI
ANTHROPIC_VERTEX_PROJECT_ID GCP project ID for Vertex AI. Required when using Google Vertex AI
API_TIMEOUT_MS Timeout for API requests in milliseconds (default: 600000, or 10 minutes; maximum: 2147483647). Increase this when requests time out on slow networks or when routing through a proxy. Values above the maximum overflow the underlying timer and cause requests to fail immediately
AWS_BEARER_TOKEN_BEDROCK Bedrock API key for authentication (see Bedrock API keys)
BASH_DEFAULT_TIMEOUT_MS Default timeout for long-running bash commands (default: 120000, or 2 minutes)
BASH_MAX_OUTPUT_LENGTH Maximum number of characters in bash outputs before they are middle-truncated
BASH_MAX_TIMEOUT_MS Maximum timeout the model can set for long-running bash commands (default: 600000, or 10 minutes)
CCR_FORCE_BUNDLE Set to 1 to force claude --remote to bundle and upload your local repository even when GitHub access is available
CLAUDECODE Set to 1 in shell environments Claude Code spawns (Bash tool, tmux sessions). Not set in hooks or status line commands. Use to detect when a script is running inside a shell spawned by Claude Code
CLAUDE_AGENT_SDK_DISABLE_BUILTIN_AGENTS Set to 1 to disable all built-in subagent types such as Explore and Plan. Only applies in non-interactive mode (the -p flag). Useful for SDK users who want a blank slate
CLAUDE_AGENT_SDK_MCP_NO_PREFIX Set to 1 to skip the mcp__<server>__ prefix on tool names from SDK-created MCP servers. Tools use their original names. SDK usage only
CLAUDE_AUTOCOMPACT_PCT_OVERRIDE Set the percentage of context capacity (1-100) at which auto-compaction triggers. By default, auto-compaction triggers at approximately 95% capacity. Use lower values like 50 to compact earlier. Values above the default threshold have no effect. Applies to both main conversations and subagents. This percentage aligns with the context_window.used_percentage field available in status line
CLAUDE_AUTO_BACKGROUND_TASKS Set to 1 to force-enable automatic backgrounding of long-running agent tasks. When enabled, subagents are moved to the background after running for approximately two minutes
CLAUDE_BASH_MAINTAIN_PROJECT_WORKING_DIR Return to the original working directory after each Bash or PowerShell command in the main session
CLAUDE_CODE_ACCESSIBILITY Set to 1 to keep the native terminal cursor visible and disable the inverted-text cursor indicator. Allows screen magnifiers like macOS Zoom to track cursor position
CLAUDE_CODE_ADDITIONAL_DIRECTORIES_CLAUDE_MD Set to 1 to load memory files from directories specified with --add-dir. Loads CLAUDE.md, .claude/CLAUDE.md, .claude/rules/*.md, and CLAUDE.local.md. By default, additional directories do not load memory files
CLAUDE_CODE_API_KEY_HELPER_TTL_MS Interval in milliseconds at which credentials should be refreshed (when using apiKeyHelper)
CLAUDE_CODE_AUTO_COMPACT_WINDOW Set the context capacity in tokens used for auto-compaction calculations. Defaults to the model's context window: 200K for standard models or 1M for extended context models. Use a lower value like 500000 on a 1M model to treat the window as 500K for compaction purposes. The value is capped at the model's actual context window. CLAUDE_AUTOCOMPACT_PCT_OVERRIDE is applied as a percentage of this value. Setting this variable decouples the compaction threshold from the status line's used_percentage, which always uses the model's full context window
CLAUDE_CODE_AUTO_CONNECT_IDE Override automatic IDE connection. By default, Claude Code connects automatically when launched inside a supported IDE's integrated terminal. Set to false to prevent this. Set to true to force a connection attempt when auto-detection fails, such as when tmux obscures the parent terminal
CLAUDE_CODE_CERT_STORE Comma-separated list of CA certificate sources for TLS connections. bundled is the Mozilla CA set shipped with Claude Code. system is the operating system trust store. Default is bundled,system. The native binary distribution is required for system store integration. On the Node.js runtime, only the bundled set is used regardless of this value
CLAUDE_CODE_CLIENT_CERT Path to client certificate file for mTLS authentication
CLAUDE_CODE_CLIENT_KEY Path to client private key file for mTLS authentication
CLAUDE_CODE_CLIENT_KEY_PASSPHRASE Passphrase for encrypted CLAUDE_CODE_CLIENT_KEY (optional)
CLAUDE_CODE_DEBUG_LOGS_DIR Override the debug log file path. Despite the name, this is a file path, not a directory. Requires debug mode to be enabled separately via --debug or /debug: setting this variable alone does not enable logging. The --debug-file flag does both at once. Defaults to ~/.claude/debug/<session-id>.txt
CLAUDE_CODE_DEBUG_LOG_LEVEL Minimum log level written to the debug log file. Values: verbose, debug (default), info, warn, error. Set to verbose to include high-volume diagnostics like full status line command output, or raise to error to reduce noise
CLAUDE_CODE_DISABLE_1M_CONTEXT Set to 1 to disable 1M context window support. When set, 1M model variants are unavailable in the model picker. Useful for enterprise environments with compliance requirements
CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING Set to 1 to disable adaptive reasoning on Opus 4.6 and Sonnet 4.6 and fall back to the fixed thinking budget controlled by MAX_THINKING_TOKENS. {/ min-version: 2.1.111 /}Has no effect on Opus 4.7, which always uses adaptive reasoning
CLAUDE_CODE_DISABLE_ATTACHMENTS Set to 1 to disable attachment processing. File mentions with @ syntax are sent as plain text instead of being expanded into file content
CLAUDE_CODE_DISABLE_AUTO_MEMORY Set to 1 to disable auto memory. Set to 0 to force auto memory on during the gradual rollout. When disabled, Claude does not create or load auto memory files
CLAUDE_CODE_DISABLE_BACKGROUND_TASKS Set to 1 to disable all background task functionality, including the run_in_background parameter on Bash and subagent tools, auto-backgrounding, and the Ctrl+B shortcut
CLAUDE_CODE_DISABLE_CLAUDE_MDS Set to 1 to prevent loading any CLAUDE.md memory files into context, including user, project, and auto-memory files
CLAUDE_CODE_DISABLE_CRON Set to 1 to disable scheduled tasks. The /loop skill and cron tools become unavailable and any already-scheduled tasks stop firing, including tasks that are already running mid-session
CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS Set to 1 to strip Anthropic-specific anthropic-beta request headers and beta tool-schema fields (such as defer_loading and eager_input_streaming) from API requests. Use this when a proxy gateway rejects requests with errors like "Unexpected value(s) for the anthropic-beta header" or "Extra inputs are not permitted". Standard fields (name, description, input_schema, cache_control) are preserved.
CLAUDE_CODE_DISABLE_FAST_MODE Set to 1 to disable fast mode
CLAUDE_CODE_DISABLE_FEEDBACK_SURVEY Set to 1 to disable the "How is Claude doing?" session quality surveys. Surveys are also disabled when DISABLE_TELEMETRY or CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC is set. See Session quality surveys
CLAUDE_CODE_DISABLE_FILE_CHECKPOINTING Set to 1 to disable file checkpointing. The /rewind command will not be able to restore code changes
CLAUDE_CODE_DISABLE_GIT_INSTRUCTIONS Set to 1 to remove built-in commit and PR workflow instructions and the git status snapshot from Claude's system prompt. Useful when using your own git workflow skills. Takes precedence over the includeGitInstructions setting when set
CLAUDE_CODE_DISABLE_LEGACY_MODEL_REMAP Set to 1 to prevent automatic remapping of Opus 4.0 and 4.1 to the current Opus version on the Anthropic API. Use when you intentionally want to pin an older model. The remap does not run on Bedrock, Vertex, or Foundry
CLAUDE_CODE_DISABLE_MOUSE Set to 1 to disable mouse tracking in fullscreen rendering. Keyboard scrolling with PgUp and PgDn still works. Use this to keep your terminal's native copy-on-select behavior
CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC Equivalent of setting DISABLE_AUTOUPDATER, DISABLE_FEEDBACK_COMMAND, DISABLE_ERROR_REPORTING, and DISABLE_TELEMETRY
CLAUDE_CODE_DISABLE_NONSTREAMING_FALLBACK Set to 1 to disable the non-streaming fallback when a streaming request fails mid-stream. Streaming errors propagate to the retry layer instead. Useful when a proxy or gateway causes the fallback to produce duplicate tool execution
CLAUDE_CODE_DISABLE_OFFICIAL_MARKETPLACE_AUTOINSTALL Set to 1 to skip automatic addition of the official plugin marketplace on first run
CLAUDE_CODE_DISABLE_TERMINAL_TITLE Set to 1 to disable automatic terminal title updates based on conversation context
CLAUDE_CODE_DISABLE_THINKING Set to 1 to force-disable extended thinking regardless of model support or other settings. More direct than MAX_THINKING_TOKENS=0
CLAUDE_CODE_DISABLE_VIRTUAL_SCROLL Set to 1 to disable virtual scrolling in fullscreen rendering and render every message in the transcript. Use this if scrolling in fullscreen mode shows blank regions where messages should appear
CLAUDE_CODE_EFFORT_LEVEL Set the effort level for supported models. Values: low, medium, high, xhigh, max, or auto to use the model default. Available levels depend on the model. Takes precedence over /effort and the effortLevel setting. See Adjust effort level
CLAUDE_CODE_ENABLE_AWAY_SUMMARY Override session recap availability. Set to 0 to force recaps off regardless of the /config toggle. Set to 1 to force recaps on when awaySummaryEnabled is false. Takes precedence over the setting and /config toggle
CLAUDE_CODE_ENABLE_BACKGROUND_PLUGIN_REFRESH Set to 1 to refresh plugin state at turn boundaries in non-interactive mode after a background install completes. Off by default because the refresh changes the system prompt mid-session, which invalidates prompt caching for that turn
CLAUDE_CODE_ENABLE_FINE_GRAINED_TOOL_STREAMING Set to 1 to force-enable fine-grained tool input streaming. Without this, the API buffers tool input parameters fully before sending delta events, which can delay display on large tool inputs. Anthropic API only: has no effect on Bedrock, Vertex, or Foundry
CLAUDE_CODE_ENABLE_PROMPT_SUGGESTION Set to false to disable prompt suggestions (the "Prompt suggestions" toggle in /config). These are the grayed-out predictions that appear in your prompt input after Claude responds. See Prompt suggestions
CLAUDE_CODE_ENABLE_TASKS Set to 1 to enable the task tracking system in non-interactive mode (the -p flag). Tasks are on by default in interactive mode. See Task list
CLAUDE_CODE_ENABLE_TELEMETRY Set to 1 to enable OpenTelemetry data collection for metrics and logging. Required before configuring OTel exporters. See Monitoring
CLAUDE_CODE_EXIT_AFTER_STOP_DELAY Time in milliseconds to wait after the query loop becomes idle before automatically exiting. Useful for automated workflows and scripts using SDK mode
CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS Set to 1 to enable agent teams. Agent teams are experimental and disabled by default
CLAUDE_CODE_FILE_READ_MAX_OUTPUT_TOKENS Override the default token limit for file reads. Useful when you need to read larger files in full
CLAUDE_CODE_GIT_BASH_PATH Windows only: path to the Git Bash executable (bash.exe). Use when Git Bash is installed but not in your PATH. See Windows setup
CLAUDE_CODE_GLOB_HIDDEN Set to false to exclude dotfiles from results when Claude invokes the Glob tool. Included by default. Does not affect @ file autocomplete, ls, Grep, or Read
CLAUDE_CODE_GLOB_NO_IGNORE Set to false to make the Glob tool respect .gitignore patterns. By default, Glob returns all matching files including gitignored ones. Does not affect @ file autocomplete, which has its own respectGitignore setting
CLAUDE_CODE_GLOB_TIMEOUT_SECONDS Timeout in seconds for Glob tool file discovery. Defaults to 20 seconds on most platforms and 60 seconds on WSL
CLAUDE_CODE_IDE_HOST_OVERRIDE Override the host address used to connect to the IDE extension. By default Claude Code auto-detects the correct address, including WSL-to-Windows routing
CLAUDE_CODE_IDE_SKIP_AUTO_INSTALL Skip auto-installation of IDE extensions. Equivalent to setting autoInstallIdeExtension to false
CLAUDE_CODE_IDE_SKIP_VALID_CHECK Set to 1 to skip validation of IDE lockfile entries during connection. Use when auto-connect fails to find your IDE despite it running
CLAUDE_CODE_MAX_CONTEXT_TOKENS Override the context window size Claude Code assumes for the active model. Only takes effect when DISABLE_COMPACT is also set. Use this when routing to a model through ANTHROPIC_BASE_URL whose context window does not match the built-in size for its name
CLAUDE_CODE_MAX_OUTPUT_TOKENS Set the maximum number of output tokens for most requests. Defaults and caps vary by model; see max output tokens. Increasing this value reduces the effective context window available before auto-compaction triggers.
CLAUDE_CODE_MAX_RETRIES Override the number of times to retry failed API requests (default: 10)
CLAUDE_CODE_MAX_TOOL_USE_CONCURRENCY Maximum number of read-only tools and subagents that can execute in parallel (default: 10). Higher values increase parallelism but consume more resources
CLAUDE_CODE_NEW_INIT Set to 1 to make /init run an interactive setup flow. The flow asks which files to generate, including CLAUDE.md, skills, and hooks, before exploring the codebase and writing them. Without this variable, /init generates a CLAUDE.md automatically without prompting.
CLAUDE_CODE_NO_FLICKER Set to 1 to enable fullscreen rendering, a research preview that reduces flicker and keeps memory flat in long conversations. Equivalent to the tui setting; you can also switch with /tui fullscreen
CLAUDE_CODE_OAUTH_REFRESH_TOKEN OAuth refresh token for Claude.ai authentication. When set, claude auth login exchanges this token directly instead of opening a browser. Requires CLAUDE_CODE_OAUTH_SCOPES. Useful for provisioning authentication in automated environments
CLAUDE_CODE_OAUTH_SCOPES Space-separated OAuth scopes the refresh token was issued with, such as "user:profile user:inference user:sessions:claude_code". Required when CLAUDE_CODE_OAUTH_REFRESH_TOKEN is set
CLAUDE_CODE_OAUTH_TOKEN OAuth access token for Claude.ai authentication. Alternative to /login for SDK and automated environments. Takes precedence over keychain-stored credentials. Generate one with claude setup-token
CLAUDE_CODE_OTEL_FLUSH_TIMEOUT_MS Timeout in milliseconds for flushing pending OpenTelemetry spans (default: 5000). See Monitoring
CLAUDE_CODE_OTEL_HEADERS_HELPER_DEBOUNCE_MS Interval for refreshing dynamic OpenTelemetry headers in milliseconds (default: 1740000 / 29 minutes). See Dynamic headers
CLAUDE_CODE_OTEL_SHUTDOWN_TIMEOUT_MS Timeout in milliseconds for the OpenTelemetry exporter to finish on shutdown (default: 2000). Increase if metrics are dropped at exit. See Monitoring
CLAUDE_CODE_PERFORCE_MODE Set to 1 to enable Perforce-aware write protection. When set, Edit, Write, and NotebookEdit fail with a p4 edit <file> hint if the target file lacks the owner-write bit, which Perforce clears on synced files until p4 edit opens them. This prevents Claude Code from bypassing Perforce change tracking
CLAUDE_CODE_PLUGIN_CACHE_DIR Override the plugins root directory. Despite the name, this sets the parent directory, not the cache itself: marketplaces and the plugin cache live in subdirectories under this path. Defaults to ~/.claude/plugins
CLAUDE_CODE_PLUGIN_GIT_TIMEOUT_MS Timeout in milliseconds for git operations when installing or updating plugins (default: 120000). Increase this value for large repositories or slow network connections. See Git operations time out
CLAUDE_CODE_PLUGIN_KEEP_MARKETPLACE_ON_FAILURE Set to 1 to keep the existing marketplace cache when a git pull fails instead of wiping and re-cloning. Useful in offline or airgapped environments where re-cloning would fail the same way. See Marketplace updates fail in offline environments
CLAUDE_CODE_PLUGIN_SEED_DIR Path to one or more read-only plugin seed directories, separated by : on Unix or ; on Windows. Use this to bundle a pre-populated plugins directory into a container image. Claude Code registers marketplaces from these directories at startup and uses pre-cached plugins without re-cloning. See Pre-populate plugins for containers
CLAUDE_CODE_PROXY_RESOLVES_HOSTS Set to 1 to allow the proxy to perform DNS resolution instead of the caller. Opt-in for environments where the proxy should handle hostname resolution
CLAUDE_CODE_REMOTE Set automatically to true when Claude Code is running as a cloud session. Read this from a hook or setup script to detect whether you are in a cloud environment
CLAUDE_CODE_REMOTE_SESSION_ID Set automatically in cloud sessions to the current session's ID. Read this to construct a link back to the session transcript. See Link artifacts back to the session
CLAUDE_CODE_RESUME_INTERRUPTED_TURN Set to 1 to automatically resume if the previous session ended mid-turn. Used in SDK mode so the model continues without requiring the SDK to re-send the prompt
CLAUDE_CODE_SCRIPT_CAPS JSON object limiting how many times specific scripts may be invoked per session when CLAUDE_CODE_SUBPROCESS_ENV_SCRUB is set. Keys are substrings matched against the command text; values are integer call limits. For example, {"deploy.sh": 2} allows deploy.sh to be called at most twice. Matching is substring-based so shell-expansion tricks like ./scripts/deploy.sh $(evil) still count against the cap. Runtime fan-out via xargs or find -exec is not detected; this is a defense-in-depth control
CLAUDE_CODE_SCROLL_SPEED Set the mouse wheel scroll multiplier in fullscreen rendering. Accepts values from 1 to 20. Set to 3 to match vim if your terminal sends one wheel event per notch without amplification
CLAUDE_CODE_SESSIONEND_HOOKS_TIMEOUT_MS Override the time budget in milliseconds for SessionEnd hooks. Applies to session exit, /clear, and switching sessions via interactive /resume. By default the budget is 1.5 seconds, automatically raised to the highest per-hook timeout configured in settings files, up to 60 seconds. Timeouts on plugin-provided hooks do not raise the budget
CLAUDE_CODE_SHELL Override automatic shell detection. Useful when your login shell differs from your preferred working shell (for example, bash vs zsh)
CLAUDE_CODE_SHELL_PREFIX Command prefix to wrap all bash commands (for example, for logging or auditing). Example: /path/to/logger.sh will execute /path/to/logger.sh <command>
CLAUDE_CODE_SIMPLE Set to 1 to run with a minimal system prompt and only the Bash, file read, and file edit tools. MCP tools from --mcp-config are still available. Disables auto-discovery of hooks, skills, plugins, MCP servers, auto memory, and CLAUDE.md. The --bare CLI flag sets this
CLAUDE_CODE_SKIP_BEDROCK_AUTH Skip AWS authentication for Bedrock (for example, when using an LLM gateway)
CLAUDE_CODE_SKIP_FOUNDRY_AUTH Skip Azure authentication for Microsoft Foundry (for example, when using an LLM gateway)
CLAUDE_CODE_SKIP_MANTLE_AUTH Skip AWS authentication for Bedrock Mantle (for example, when using an LLM gateway)
CLAUDE_CODE_SKIP_PROMPT_HISTORY Set to 1 to skip writing prompt history and session transcripts to disk. Sessions started with this variable set do not appear in --resume, --continue, or up-arrow history. Useful for ephemeral scripted sessions
CLAUDE_CODE_SKIP_VERTEX_AUTH Skip Google authentication for Vertex (for example, when using an LLM gateway)
CLAUDE_CODE_SUBAGENT_MODEL See Model configuration
CLAUDE_CODE_SUBPROCESS_ENV_SCRUB Set to 1 to strip Anthropic and cloud provider credentials from subprocess environments (Bash tool, hooks, MCP stdio servers). The parent Claude process keeps these credentials for API calls, but child processes cannot read them, reducing exposure to prompt injection attacks that attempt to exfiltrate secrets via shell expansion. On Linux, this also runs Bash subprocesses in an isolated PID namespace so they cannot read host process environments via /proc; as a side effect, ps, pgrep, and kill cannot see or signal host processes. claude-code-action sets this automatically when allowed_non_write_users is configured
CLAUDE_CODE_SYNC_PLUGIN_INSTALL Set to 1 in non-interactive mode (the -p flag) to wait for plugin installation to complete before the first query. Without this, plugins install in the background and may not be available on the first turn. Combine with CLAUDE_CODE_SYNC_PLUGIN_INSTALL_TIMEOUT_MS to bound the wait
CLAUDE_CODE_SYNC_PLUGIN_INSTALL_TIMEOUT_MS Timeout in milliseconds for synchronous plugin installation. When exceeded, Claude Code proceeds without plugins and logs an error. No default: without this variable, synchronous installation waits until complete
CLAUDE_CODE_SYNTAX_HIGHLIGHT Set to false to disable syntax highlighting in diff output. Useful when colors interfere with your terminal setup
CLAUDE_CODE_TASK_LIST_ID Share a task list across sessions. Set the same ID in multiple Claude Code instances to coordinate on a shared task list. See Task list
CLAUDE_CODE_TEAM_NAME Name of the agent team this teammate belongs to. Set automatically on agent team members
CLAUDE_CODE_TMPDIR Override the temp directory used for internal temp files. Claude Code appends /claude-{uid}/ (Unix) or /claude/ (Windows) to this path. Default: /tmp on macOS, os.tmpdir() on Linux/Windows
CLAUDE_CODE_TMUX_TRUECOLOR Set to 1 to allow 24-bit truecolor output inside tmux. By default, Claude Code clamps to 256 colors when $TMUX is set because tmux does not pass through truecolor escape sequences unless configured to. Set this after adding set -ga terminal-overrides ',*:Tc' to your ~/.tmux.conf. See Terminal configuration for other tmux settings
CLAUDE_CODE_USE_BEDROCK Use Bedrock
CLAUDE_CODE_USE_FOUNDRY Use Microsoft Foundry
CLAUDE_CODE_USE_MANTLE Use the Bedrock Mantle endpoint
CLAUDE_CODE_USE_POWERSHELL_TOOL Controls the PowerShell tool. On Windows, the tool is rolling out progressively: set to 1 to opt in or 0 to opt out. On Linux, macOS, and WSL, set to 1 to enable it, which requires pwsh on your PATH. When enabled on Windows, Claude can run PowerShell commands natively instead of routing through Git Bash. See PowerShell tool
CLAUDE_CODE_USE_VERTEX Use Vertex
CLAUDE_CONFIG_DIR Override the configuration directory (default: ~/.claude). All settings, credentials, session history, and plugins are stored under this path. Useful for running multiple accounts side by side: for example, alias claude-work='CLAUDE_CONFIG_DIR=~/.claude-work claude'
CLAUDE_ENABLE_BYTE_WATCHDOG Set to 1 to force-enable the byte-level streaming idle watchdog, or set to 0 to force-disable it. When unset, the watchdog is enabled by default for Anthropic API connections. The byte watchdog aborts a connection when no bytes arrive on the wire for the duration set by CLAUDE_STREAM_IDLE_TIMEOUT_MS, with a minimum of 5 minutes, independent of the event-level watchdog
CLAUDE_ENABLE_STREAM_WATCHDOG Set to 1 to enable the event-level streaming idle watchdog. Off by default. For Bedrock, Vertex, and Foundry, this is the only idle watchdog available. Configure the timeout with CLAUDE_STREAM_IDLE_TIMEOUT_MS
CLAUDE_ENV_FILE Path to a shell script that Claude Code sources before each Bash command. Use to persist virtualenv or conda activation across commands. Also populated dynamically by SessionStart, CwdChanged, and FileChanged hooks
CLAUDE_REMOTE_CONTROL_SESSION_NAME_PREFIX Prefix for auto-generated Remote Control session names when no explicit name is provided. Defaults to your machine's hostname, producing names like myhost-graceful-unicorn. The --remote-control-session-name-prefix CLI flag sets the same value for a single invocation
CLAUDE_STREAM_IDLE_TIMEOUT_MS Timeout in milliseconds before the streaming idle watchdog closes a stalled connection. For the byte-level watchdog on the Anthropic API: default and minimum 300000 (5 minutes); lower values are silently clamped to absorb extended thinking pauses and proxy buffering. For the event-level watchdog: default 90000 (90 seconds), no minimum. For third-party providers, requires CLAUDE_ENABLE_STREAM_WATCHDOG=1
DISABLE_AUTOUPDATER Set to 1 to disable automatic updates
DISABLE_AUTO_COMPACT Set to 1 to disable automatic compaction when approaching the context limit. The manual /compact command remains available. Use when you want explicit control over when compaction occurs
DISABLE_COMPACT Set to 1 to disable all compaction: both automatic compaction and the manual /compact command
DISABLE_COST_WARNINGS Set to 1 to disable cost warning messages
DISABLE_DOCTOR_COMMAND Set to 1 to hide the /doctor command. Useful for managed deployments where users should not run installation diagnostics
DISABLE_ERROR_REPORTING Set to 1 to opt out of Sentry error reporting
DISABLE_EXTRA_USAGE_COMMAND Set to 1 to hide the /extra-usage command that lets users purchase additional usage beyond rate limits
DISABLE_FEEDBACK_COMMAND Set to 1 to disable the /feedback command. The older name DISABLE_BUG_COMMAND is also accepted
DISABLE_INSTALLATION_CHECKS Set to 1 to disable installation warnings. Use only when manually managing the installation location, as this can mask issues with standard installations
DISABLE_INSTALL_GITHUB_APP_COMMAND Set to 1 to hide the /install-github-app command. Already hidden when using third-party providers (Bedrock, Vertex, or Foundry)
DISABLE_INTERLEAVED_THINKING Set to 1 to prevent sending the interleaved-thinking beta header. Useful when your LLM gateway or provider does not support interleaved thinking
DISABLE_LOGIN_COMMAND Set to 1 to hide the /login command. Useful when authentication is handled externally via API keys or apiKeyHelper
DISABLE_LOGOUT_COMMAND Set to 1 to hide the /logout command
DISABLE_PROMPT_CACHING Set to 1 to disable prompt caching for all models (takes precedence over per-model settings)
DISABLE_PROMPT_CACHING_HAIKU Set to 1 to disable prompt caching for Haiku models
DISABLE_PROMPT_CACHING_OPUS Set to 1 to disable prompt caching for Opus models
DISABLE_PROMPT_CACHING_SONNET Set to 1 to disable prompt caching for Sonnet models
DISABLE_TELEMETRY Set to 1 to opt out of Statsig telemetry (note that Statsig events do not include user data like code, file paths, or bash commands)
DISABLE_UPGRADE_COMMAND Set to 1 to hide the /upgrade command
ENABLE_CLAUDEAI_MCP_SERVERS Set to false to disable claude.ai MCP servers in Claude Code. Enabled by default for logged-in users
ENABLE_PROMPT_CACHING_1H Set to 1 to request a 1-hour prompt cache TTL instead of the default 5 minutes. Intended for API key, Bedrock, Vertex, and Foundry users. Subscription users receive 1-hour TTL automatically. 1-hour cache writes are billed at a higher rate
ENABLE_PROMPT_CACHING_1H_BEDROCK Deprecated. Use ENABLE_PROMPT_CACHING_1H instead
ENABLE_TOOL_SEARCH Controls MCP tool search. Unset: all MCP tools deferred by default, but loaded upfront when ANTHROPIC_BASE_URL points to a non-first-party host. Values: true (always defer including proxies), auto (threshold mode: load upfront if tools fit within 10% of context), auto:N (custom threshold, e.g., auto:5 for 5%), false (load all upfront)
FALLBACK_FOR_ALL_PRIMARY_MODELS Set to any non-empty value to trigger fallback to --fallback-model after repeated overload errors on any primary model. By default, only Opus models trigger the fallback
FORCE_AUTOUPDATE_PLUGINS Set to 1 to force plugin auto-updates even when the main auto-updater is disabled via DISABLE_AUTOUPDATER
FORCE_PROMPT_CACHING_5M Set to 1 to force the 5-minute prompt cache TTL even when 1-hour TTL would otherwise apply. Overrides ENABLE_PROMPT_CACHING_1H
HTTP_PROXY Specify HTTP proxy server for network connections
HTTPS_PROXY Specify HTTPS proxy server for network connections
IS_DEMO Set to 1 to enable demo mode: hides your email and organization name from the header and /status output, and skips onboarding. Useful when streaming or recording a session
MAX_MCP_OUTPUT_TOKENS Maximum number of tokens allowed in MCP tool responses. Claude Code displays a warning when output exceeds 10,000 tokens. Tools that declare anthropic/maxResultSizeChars use that character limit for text content instead, but image content from those tools is still subject to this variable (default: 25000)
MAX_STRUCTURED_OUTPUT_RETRIES Number of times to retry when the model's response fails validation against the --json-schema in non-interactive mode (the -p flag). Defaults to 5
MAX_THINKING_TOKENS Override the extended thinking token budget. The ceiling is the model's max output tokens minus one. Set to 0 to disable thinking entirely. On models with adaptive reasoning, the budget is ignored unless adaptive reasoning is disabled via CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING
MCP_CLIENT_SECRET OAuth client secret for MCP servers that require pre-configured credentials. Avoids the interactive prompt when adding a server with --client-secret
MCP_CONNECTION_NONBLOCKING Set to true in non-interactive mode (-p) to skip the MCP connection wait entirely. Useful for scripted pipelines where MCP tools are not needed. Without this variable, the first query waits up to 5 seconds for --mcp-config server connections
MCP_OAUTH_CALLBACK_PORT Fixed port for the OAuth redirect callback, as an alternative to --callback-port when adding an MCP server with pre-configured credentials
MCP_REMOTE_SERVER_CONNECTION_BATCH_SIZE Maximum number of remote MCP servers (HTTP/SSE) to connect in parallel during startup (default: 20)
MCP_SERVER_CONNECTION_BATCH_SIZE Maximum number of local MCP servers (stdio) to connect in parallel during startup (default: 3)
MCP_TIMEOUT Timeout in milliseconds for MCP server startup (default: 30000, or 30 seconds)
MCP_TOOL_TIMEOUT Timeout in milliseconds for MCP tool execution (default: 100000000, about 28 hours)
NO_PROXY List of domains and IPs to which requests will be directly issued, bypassing proxy
OTEL_LOG_RAW_API_BODIES Set to 1 to emit the full Anthropic Messages API request and response JSON as OpenTelemetry log events (api_request_body, api_response_body). Disabled by default; bodies include the entire conversation history. See Monitoring
OTEL_LOG_TOOL_CONTENT Set to 1 to include tool input and output content in OpenTelemetry span events. Disabled by default to protect sensitive data. See Monitoring
OTEL_LOG_TOOL_DETAILS Set to 1 to include tool input arguments, MCP server names, and tool details in OpenTelemetry traces and logs. Disabled by default to protect PII. See Monitoring
OTEL_LOG_USER_PROMPTS Set to 1 to include user prompt text in OpenTelemetry traces and logs. Disabled by default (prompts are redacted). See Monitoring
OTEL_METRICS_INCLUDE_ACCOUNT_UUID Set to false to exclude account UUID from metrics attributes (default: included). See Monitoring
OTEL_METRICS_INCLUDE_SESSION_ID Set to false to exclude session ID from metrics attributes (default: included). See Monitoring
OTEL_METRICS_INCLUDE_VERSION Set to true to include Claude Code version in metrics attributes (default: excluded). See Monitoring
SLASH_COMMAND_TOOL_CHAR_BUDGET Override the character budget for skill metadata shown to the Skill tool. The budget scales dynamically at 1% of the context window, with a fallback of 8,000 characters. Legacy name kept for backwards compatibility
TASK_MAX_OUTPUT_LENGTH Maximum number of characters in subagent output before truncation (default: 32000, maximum: 160000). When truncated, the full output is saved to disk and the path is included in the truncated response
USE_BUILTIN_RIPGREP Set to 0 to use system-installed rg instead of rg included with Claude Code
VERTEX_REGION_CLAUDE_3_5_HAIKU Override region for Claude 3.5 Haiku when using Vertex AI
VERTEX_REGION_CLAUDE_3_5_SONNET Override region for Claude 3.5 Sonnet when using Vertex AI
VERTEX_REGION_CLAUDE_3_7_SONNET Override region for Claude 3.7 Sonnet when using Vertex AI
VERTEX_REGION_CLAUDE_4_0_OPUS Override region for Claude 4.0 Opus when using Vertex AI
VERTEX_REGION_CLAUDE_4_0_SONNET Override region for Claude 4.0 Sonnet when using Vertex AI
VERTEX_REGION_CLAUDE_4_1_OPUS Override region for Claude 4.1 Opus when using Vertex AI
VERTEX_REGION_CLAUDE_4_5_OPUS Override region for Claude Opus 4.5 when using Vertex AI
VERTEX_REGION_CLAUDE_4_5_SONNET Override region for Claude Sonnet 4.5 when using Vertex AI
VERTEX_REGION_CLAUDE_4_6_OPUS Override region for Claude Opus 4.6 when using Vertex AI
VERTEX_REGION_CLAUDE_4_6_SONNET Override region for Claude Sonnet 4.6 when using Vertex AI
VERTEX_REGION_CLAUDE_4_7_OPUS {/ min-version: 2.1.111 /}Override region for Claude Opus 4.7 when using Vertex AI
VERTEX_REGION_CLAUDE_HAIKU_4_5 Override region for Claude Haiku 4.5 when using Vertex AI

Standard OpenTelemetry exporter variables (OTEL_METRICS_EXPORTER, OTEL_LOGS_EXPORTER, OTEL_EXPORTER_OTLP_ENDPOINT, OTEL_EXPORTER_OTLP_PROTOCOL, OTEL_EXPORTER_OTLP_HEADERS, OTEL_METRIC_EXPORT_INTERVAL, OTEL_RESOURCE_ATTRIBUTES, and signal-specific variants) are also supported. See Monitoring for configuration details.

See also