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Execution Environment

Bash & Shell

`BASH_MAX_OUTPUT_LENGTH`

Type: Integer (characters)
Default: 30000
Upper limit: 150000
Description: Maximum output length for bash commands. Longer outputs are truncated. Must be > 0 and <= 150000.
Example: export BASH_MAX_OUTPUT_LENGTH=50000

`TASK_MAX_OUTPUT_LENGTH`

Type: Integer (characters)
Default: Unspecified (typically same as BASH_MAX_OUTPUT_LENGTH)
Description: Maximum output length for task results. Truncates long task outputs.
Example: export TASK_MAX_OUTPUT_LENGTH=50000

`CLAUDE_BASH_MAINTAIN_PROJECT_WORKING_DIR`

Type: Boolean (1, true, 0, false)
Default: false
Description: Maintain the project working directory across bash commands. When true, each bash invocation resumes in the previous directory context.
Example: export CLAUDE_BASH_MAINTAIN_PROJECT_WORKING_DIR=1

`CLAUDE_CODE_USE_POWERSHELL_TOOL`

Type: Boolean (1, true, 0, false)
Default: false
Description: Use PowerShell instead of Bash for shell commands. Useful on Windows or when PowerShell is preferred.
Example: export CLAUDE_CODE_USE_POWERSHELL_TOOL=1

`CLAUDE_CODE_GIT_BASH_PATH`

Type: String (path to bash executable)
Default: Auto-detected on Windows
Description: Path to git bash executable on Windows. Overrides auto-detection.
Example: export CLAUDE_CODE_GIT_BASH_PATH="C:\\Program Files\\Git\\bin\\bash.exe"

`CLAUDE_CODE_PWSH_PARSE_TIMEOUT_MS`

Type: Integer (milliseconds)
Default: Unspecified (typically 5000 ms)
Description: PowerShell command parse timeout in milliseconds. Parsed as int; must be > 0.
Example: export CLAUDE_CODE_PWSH_PARSE_TIMEOUT_MS=10000

`SLASH_COMMAND_TOOL_CHAR_BUDGET`

Type: Integer (characters)
Default: Unspecified
Description: Character budget for slash command tool output. Truncates long outputs from /command invocations.
Example: export SLASH_COMMAND_TOOL_CHAR_BUDGET=10000

Tool Configuration

`CLAUDE_CODE_MAX_TOOL_USE_CONCURRENCY`

Type: Integer
Default: 10
Description: Maximum concurrent tool use operations. Higher values allow parallel tool execution but consume more resources.
Example: export CLAUDE_CODE_MAX_TOOL_USE_CONCURRENCY=20

`CLAUDE_CODE_FILE_READ_MAX_OUTPUT_TOKENS`

Type: Integer (tokens)
Default: Unspecified (typically 10000)
Description: Maximum output tokens when reading files. Longer files are truncated to this token limit.
Example: export CLAUDE_CODE_FILE_READ_MAX_OUTPUT_TOKENS=50000

`CLAUDE_CODE_GLOB_TIMEOUT_SECONDS`

Type: Integer (seconds)
Default: Unspecified (typically 30)
Description: Timeout in seconds for glob operations. Prevents hangs on slow filesystems.
Example: export CLAUDE_CODE_GLOB_TIMEOUT_SECONDS=60

`CLAUDE_CODE_GLOB_HIDDEN`

Type: Boolean (1, true, 0, false)
Default: false
Description: Include hidden files in glob searches. When true, globs match .hidden files.
Example: export CLAUDE_CODE_GLOB_HIDDEN=1

`CLAUDE_CODE_GLOB_NO_IGNORE`

Type: Boolean (1, true, 0, false)
Default: false
Description: Don’t respect .gitignore in glob searches. When true, ignores .gitignore rules.
Example: export CLAUDE_CODE_GLOB_NO_IGNORE=1

`USE_BUILTIN_RIPGREP`

Type: Boolean (1, true, 0, false)
Default: false
Description: Use the built-in ripgrep binary instead of system ripgrep. Useful when system ripgrep is unavailable or outdated.
Example: export USE_BUILTIN_RIPGREP=1

`CLAUDE_CODE_EMIT_TOOL_USE_SUMMARIES`

Type: Boolean (1, true, 0, false)
Default: false
Description: Emit summary descriptions for tool use actions. Shows human-readable summaries of tool calls.
Example: export CLAUDE_CODE_EMIT_TOOL_USE_SUMMARIES=1

`CLAUDE_CODE_INCLUDE_PARTIAL_MESSAGES`

Type: Boolean (1, true, 0, false)
Default: false
Description: Include partial/streaming messages in output. Shows in-flight messages as they arrive.
Example: export CLAUDE_CODE_INCLUDE_PARTIAL_MESSAGES=1

`CLAUDE_CODE_BASH_SANDBOX_SHOW_INDICATOR`

Type: Boolean (1, true, 0, false)
Default: false
Description: Show ‘SandboxedBash’ label when sandbox is active. Useful for visibility in sandboxed environments.
Example: export CLAUDE_CODE_BASH_SANDBOX_SHOW_INDICATOR=1

`MAX_STRUCTURED_OUTPUT_RETRIES`

Type: Integer
Default: 5
Description: Maximum retries for structured output parsing. Higher values retry more on parse failures.
Example: export MAX_STRUCTURED_OUTPUT_RETRIES=10

`USE_API_CONTEXT_MANAGEMENT`

Type: Boolean (1, true, 0, false)
Default: false
Description: Use API-side context management instead of client-side. Delegates context handling to the API.
Example: export USE_API_CONTEXT_MANAGEMENT=1

Node.js & Bun Runtime

`NODE_ENV`

Type: String (enum: development, production, test)
Default: production
Description: Node.js environment. Affects module loading, optimizations, and error handling.
Example: export NODE_ENV=development

`NODE_OPTIONS`

Type: String (Node.js CLI options)
Default: Unspecified
Description: Additional Node.js CLI options. Passed to the Node.js runtime.
Example: export NODE_OPTIONS='--max-old-space-size=4096'

`NODE_DEBUG`

Type: String (module filter)
Default: Unspecified
Description: Node.js debug module filter. Enables debug output for specific modules.
Example: export NODE_DEBUG=http,net

`NODE_UNIQUE_ID`

Type: String (worker ID)
Default: Unspecified
Description: Node.js cluster worker unique ID. Used in cluster mode.
Example: export NODE_UNIQUE_ID=worker-1

`NODE_CLUSTER_SCHED_POLICY`

Type: String (enum: rr, none)
Default: rr (round-robin)
Description: Node.js cluster scheduling policy. Controls how OS assigns connections to workers.
Example: export NODE_CLUSTER_SCHED_POLICY=none

`BUN_ENV`

Type: String (enum: development, production)
Default: production
Description: Bun runtime environment. Similar to NODE_ENV but for Bun.
Example: export BUN_ENV=development

`BUN_INSTALL`

Type: String (directory path)
Default: ~/.bun
Description: Bun installation directory. Where Bun stores packages and cache.
Example: export BUN_INSTALL=/opt/bun

`BUN_FEEDBACK_URL`

Type: URL
Default: https://bun.report/v1/feedback
Description: URL for Bun feedback submission.
Example: export BUN_FEEDBACK_URL=https://internal.bun.report/feedback

`BUN_DISABLE_DYNAMIC_CHUNK_SIZE`

Type: Boolean (1, 0)
Default: false
Description: Set to ‘1’ to disable dynamic chunk sizing in Bun. Forces fixed chunk sizes.
Example: export BUN_DISABLE_DYNAMIC_CHUNK_SIZE=1

`BUN_INSPECT_NOTIFY`

Type: String (unix:// URL)
Default: Unspecified
Description: URL for Bun inspector notification. Used with debuggers.
Example: export BUN_INSPECT_NOTIFY=unix:///tmp/bun-inspect.sock

`BUN_JS_DEBUG`

Type: Boolean (1, 0)
Default: false
Description: Enable Bun JavaScript debug logging.
Example: export BUN_JS_DEBUG=1

`UV_THREADPOOL_SIZE`

Type: Integer
Default: 4 (or CPU count, whichever is higher)
Description: libuv thread pool size for async I/O. Affects concurrency of filesystem and DNS operations.
Example: export UV_THREADPOOL_SIZE=16

`COREPACK_ENABLE_AUTO_PIN`

Type: Boolean (1, true, 0, false)
Default: false
Description: Enable Corepack auto-pinning of package managers. Automatically pins npm/yarn/pnpm versions.
Example: export COREPACK_ENABLE_AUTO_PIN=1

`SHARP_FORCE_GLOBAL_LIBVIPS`

Type: Boolean (1, true, 0, false)
Default: false
Description: Force Sharp (image library) to use globally installed libvips. Useful for system-wide image library sharing.
Example: export SHARP_FORCE_GLOBAL_LIBVIPS=1

`SHARP_IGNORE_GLOBAL_LIBVIPS`

Type: Boolean (1, true, 0, false)
Default: false
Description: Force Sharp to ignore globally installed libvips. Uses bundled libvips instead.
Example: export SHARP_IGNORE_GLOBAL_LIBVIPS=1

`GRACEFUL_FS_PLATFORM`

Type: String (platform identifier)
Default: Auto-detected
Description: Override platform detection for graceful-fs. Useful when auto-detection fails.
Example: export GRACEFUL_FS_PLATFORM=linux

`MODIFIERS_NODE_PATH`

Type: String (directory path)
Default: Unspecified
Description: Custom Node.js path for module resolution. Prepended to NODE_PATH.
Example: export MODIFIERS_NODE_PATH=/custom/node/modules

`PKG_CONFIG_PATH`

Type: String (colon-separated paths)
Default: System defaults
Description: pkg-config search path. Used for locating system libraries.
Example: export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:/opt/lib/pkgconfig

gRPC

`GRPC_VERBOSITY`

Type: String (enum: DEBUG, INFO, ERROR, NONE)
Default: ERROR
Description: gRPC log verbosity level. Controls how much gRPC logs are emitted.
Example: export GRPC_VERBOSITY=DEBUG

`GRPC_TRACE`

Type: String (comma-separated trace categories)
Default: Unspecified (no tracing)
Description: gRPC trace categories for debugging. Enables extra logging for specific internal components.
Example: export GRPC_TRACE=all

`GRPC_NODE_VERBOSITY`

Type: String (log level)
Default: Unspecified
Description: gRPC Node.js specific verbosity level.
Example: export GRPC_NODE_VERBOSITY=debug

`GRPC_NODE_TRACE`

Type: String (comma-separated categories)
Default: Unspecified
Description: gRPC Node.js specific trace categories.
Example: export GRPC_NODE_TRACE=channel

`GRPC_NODE_USE_ALTERNATIVE_RESOLVER`

Type: Boolean (1, true, 0, false)
Default: false
Description: Use alternative DNS resolver for gRPC in Node.js. Useful when default resolver is unreliable.
Example: export GRPC_NODE_USE_ALTERNATIVE_RESOLVER=1

`GRPC_SSL_CIPHER_SUITES`

Type: String (colon-separated cipher suite names)
Default: OpenSSL defaults
Description: Override SSL cipher suites for gRPC connections. Controls cryptographic algorithms used.
Example: export GRPC_SSL_CIPHER_SUITES=HIGH:!aNULL:!MD5

`GRPC_DEFAULT_SSL_ROOTS_FILE_PATH`

Type: String (file path to PEM)
Default: System CA bundle
Description: Path to custom SSL roots file for gRPC. Overrides default CA certificates.
Example: export GRPC_DEFAULT_SSL_ROOTS_FILE_PATH=/etc/ssl/certs/ca-bundle.crt

`GRPC_EXPERIMENTAL_ENABLE_OUTLIER_DETECTION`

Type: Boolean (1, true, 0, false)
Default: false
Description: Enable experimental gRPC outlier detection. Detects and avoids unhealthy servers.
Example: export GRPC_EXPERIMENTAL_ENABLE_OUTLIER_DETECTION=1

Tmux

`CLAUDE_CODE_TMUX_PREFIX`

Type: String (key binding, e.g., C-b, C-a)
Default: Detected from tmux config
Description: Override the tmux prefix key. Useful when your tmux config uses a non-standard prefix.
Example: export CLAUDE_CODE_TMUX_PREFIX=C-a

`CLAUDE_CODE_TMUX_PREFIX_CONFLICTS`

Type: Boolean (1, true, 0, false)
Default: false
Description: Handle tmux prefix key conflicts. When true, manages prefix conflicts with other programs.
Example: export CLAUDE_CODE_TMUX_PREFIX_CONFLICTS=1

`CLAUDE_CODE_TMUX_SESSION`

Type: String (session name)
Default: Auto-generated
Description: Tmux session name for Claude Code. Defaults to a generated name if not set.
Example: export CLAUDE_CODE_TMUX_SESSION=claude-main

`CLAUDE_CODE_TMUX_TRUECOLOR`

Type: Boolean (1, true, 0, false)
Default: false
Description: Preserve detected truecolor level under tmux. When set, prevents automatic downgrade to 256 colors inside tmux.
Example: export CLAUDE_CODE_TMUX_TRUECOLOR=1

`TMUX`

Type: String (socket path)
Default: Detected automatically when running inside tmux
Description: Set automatically when running inside tmux. Not typically set manually.
Example: /tmp/tmux-1000/default

`TMUX_PANE`

Type: String (pane identifier, e.g., %0)
Default: Detected automatically
Description: Current tmux pane identifier. Detected automatically when running inside tmux.
Example: %0

Terminal Detection

`TERM`

Type: String (terminal identifier)
Default: Auto-detected (usually xterm-256color or similar)
Description: Terminal type identifier. Affects color support, cursor movement, etc. Auto-detected by most terminal emulators.
Example: export TERM=xterm-256color

`COLORTERM`

Type: String (color capability, e.g., truecolor, 256color)
Default: Auto-detected
Description: Color terminal capability. Indicates 24-bit truecolor, 256-color, or basic color support.
Example: export COLORTERM=truecolor

`FORCE_COLOR`

Type: Boolean (1, true, 0, false)
Default: Auto-detected based on TERM and TTY
Description: Force color output regardless of terminal detection. Set to 0 to disable colors.
Example: export FORCE_COLOR=1

`COLORFGBG`

Type: String (color codes, e.g., “15;0”)
Default: Unspecified
Description: Terminal foreground/background color hint. Parsed to detect dark (0-6, 8) vs light theme.
Example: export COLORFGBG=15;0

`ITERM_SESSION_ID`

Type: String (session ID)
Default: Unspecified (set by iTerm2)
Description: iTerm2 session identifier. Detected when running inside iTerm2.
Example: w0t0p0:1234567-89AB-CDEF

`TERM_PROGRAM`

Type: String (program name)
Default: Unspecified
Description: Terminal program name (e.g., iTerm.app, Apple_Terminal). Used for terminal detection.
Example: export TERM_PROGRAM=iTerm.app

`TERM_PROGRAM_VERSION`

Type: String (version string)
Default: Unspecified
Description: Terminal program version.
Example: export TERM_PROGRAM_VERSION=3.4.0

`KITTY_WINDOW_ID`

Type: Integer
Default: Unspecified (set by Kitty terminal)
Description: Kitty terminal window ID. Detected when running inside Kitty.
Example: 1

`ALACRITTY_LOG`

Type: String (file path)
Default: Unspecified
Description: Alacritty terminal log path. Used for terminal detection.
Example: /tmp/alacritty.log

`GNOME_TERMINAL_SERVICE`

Type: String (D-Bus service name)
Default: Unspecified
Description: GNOME Terminal service name. Detected when running inside GNOME Terminal.
Example: org.gnome.Terminal

`VTE_VERSION`

Type: Integer (version number)
Default: Unspecified
Description: VTE (GNOME Terminal) version. Indicates terminal capabilities.
Example: 5000

`KONSOLE_VERSION`

Type: Integer
Default: Unspecified
Description: KDE Konsole version. Detected when running inside Konsole.
Example: 200000

`XTERM_VERSION`

Type: Integer
Default: Unspecified
Description: xterm version. Detected when running inside xterm.
Example: 379

`TILIX_ID`

Type: String (terminal ID)
Default: Unspecified
Description: Tilix terminal ID. Detected when running inside Tilix.
Example: 1234567890

`TERMINATOR_UUID`

Type: String (UUID)
Default: Unspecified
Description: Terminator terminal UUID. Detected when running inside Terminator.
Example: ffffffff-ffff-ffff-ffff-ffffffffffff

`TERMINAL`

Type: String (terminal identifier)
Default: Unspecified
Description: Generic terminal identifier for detection.
Example: xterm

`TERMINAL_EMULATOR`

Type: String (emulator identifier)
Default: Unspecified
Description: Terminal emulator identifier (e.g., JetBrains-JediTerm).
Example: JetBrains-JediTerm

`WT_SESSION`

Type: String (session GUID)
Default: Unspecified (set by Windows Terminal)
Description: Windows Terminal session ID. Detected when running inside Windows Terminal.
Example: 11111111-1111-1111-1111-111111111111

`SESSIONNAME`

Type: String
Default: Unspecified (set by Windows)
Description: Windows session name. Used for terminal detection on Windows.
Example: Console

`BAT_THEME`

Type: String (theme name)
Default: Unspecified (bat uses default theme)
Description: Theme for bat syntax highlighter. Used when displaying code in the terminal.
Example: export BAT_THEME=Monokai Extended

`CLI_WIDTH`

Type: Integer (characters)
Default: Auto-detected from terminal width
Description: Override terminal width for formatting. Useful when auto-detection fails.
Example: export CLI_WIDTH=120

`LC_TERMINAL`

Type: String (terminal identifier)
Default: Unspecified
Description: Terminal identifier from locale settings.
Example: xterm-256color

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