Tools and Bash

These variables change how tools run. They set Bash time limits and output size, shell choice, search behavior, permission helpers, and the sandbox. Use them when long commands time out or when you need to limit what a tool can see.

This page lists 102 variables. BASH_DEFAULT_TIMEOUT_MS and BASH_MAX_OUTPUT_LENGTH are common. Switch rows take 1 or 0.

Example

~/.claude/settings.json

{
  "env": {
    "BASH_DEFAULT_TIMEOUT_MS": "300000",
    "BASH_MAX_OUTPUT_LENGTH": "60000"
  }
}

A Bash call now waits up to five minutes before it times out.

Variables

The table is sorted by name. See Environment Variables for what each column and badge means.

Variable	Status	What it does	Values and default	Notes
AUTOMODE_DECISION_LOG	Undocumented	When the value is 1, Claude Code appends each auto mode decision to .automode_decisions.jsonl.	Only the exact value 1 works. The log is skipped in one runtime mode	Auto mode, all. Not set from project env before trust
BASH_DEFAULT_TIMEOUT_MS	Documented	Sets the default timeout of a foreground Bash or PowerShell command.	A number of milliseconds, 120000 by default. Positive number, default 120000. Invalid values fall back to the default	All sessions. Project env can set it before trust
BASH_MAX_OUTPUT_LENGTH	Documented	Caps the characters of Bash output that Claude reads back into the result.	A number, 30000 by default. Integer, default 30000, max 150000. The bashOutputMaxChars setting wins when set	All sessions. Project env can set it before trust
BASH_MAX_TIMEOUT_MS	Documented	Sets the highest timeout the model may ask for on a foreground Bash or PowerShell command.	A number of milliseconds, 600000 by default. Positive number, default 600000. The ceiling is the larger of this and BASH_DEFAULT_TIMEOUT_MS	All sessions. Project env can set it before trust
CLAUDE_BASH_MAINTAIN_PROJECT_WORKING_DIR	Documented	Returns to the project working directory after each Bash or PowerShell command in the main session.	On or off	Main session. Project env can set it before trust
CLAUDE_BG_SESSION_PERMISSION_RULES	Undocumented	Gives allow and deny permission rules and extra dirs to a background session as JSON.	JSON text. Used only when CLAUDE_CODE_SESSION_KIND is bg. Scrubbed from child env	Background sessions. Not set from project env before trust
CLAUDE_CHROME_CLASSIFIER_FLOOR	Undocumented	Forces the Chrome auto mode classifier floor on or off. It overrides a feature flag. No visible effect in a print-mode probe (Probes).	On, off, or unset, false by default. Without it the flag decides, default false. Remote sessions read the flag in safe mode	Claude in Chrome with auto mode. Not set from project env before trust
CLAUDE_CHROME_PERMISSION_MODE	Undocumented	Sets the permission mode of Claude in Chrome. No visible effect in a print-mode probe (Probes).	Text. An unknown value logs a warning. Claude Code sets skip_all_permission_checks for the native host when permission checks are skipped	Claude in Chrome. Not set from project env before trust
CLAUDE_CODE_ADOPT_UNDERIVABLE_PARKED_PERMISSION	Undocumented	Lets a resumed session adopt a parked sidechain permission that it cannot re-derive. It then does not re-run the permission.	On or off. Part of the parked permission settings. A log line names this var when it adopts one	Print and SDK mode with parked permissions. Not set from project env before trust
CLAUDE_CODE_AUTO_BACKGROUND_TIMEOUT_MS	Undocumented	Caps the timeout of a Bash call that can auto-background in the main agent.	A number of milliseconds. The cap is at least 2000. A missing or non-positive value is ignored	Main agent, Bash
CLAUDE_CODE_AUTO_MODE_ARTIFACT_CONSENT_RULE	Undocumented Gated	Turns the artifact consent rule of the auto mode classifier on or off.	On by default. Env value wins. Else a feature flag set to true turns it off	Auto mode, gated by a feature flag
CLAUDE_CODE_AUTO_MODE_CLASSIFY_ASK_USER_QUESTION	Undocumented	Overrides whether the auto mode classifier looks at AskUserQuestion calls.	On by default. Env value, else the classifyAskUserQuestion server setting	Auto mode
CLAUDE_CODE_AUTO_MODE_CLASSIFY_EDITS	Undocumented	Overrides whether the auto mode classifier checks file edits.	Env value, else a per-model server setting classifyEditsModels	Auto mode
CLAUDE_CODE_AUTO_MODE_COMPACT_THREAD_RULE	Undocumented Gated	Picks the compact or the original thread rule for the auto mode classifier in a bound Slack thread.	Off by default. Env value, else a feature flag, default off	Auto mode, gated by a feature flag
CLAUDE_CODE_AUTO_MODE_EDIT_REMOVAL	Undocumented	Turns on edit removal visibility in the auto mode classifier input.	Off by default. Env value, else the server setting editRemovalVisibility, default off	Auto mode
CLAUDE_CODE_AUTO_MODE_EDIT_REMOVAL_CAP	Undocumented	Sets the size cap for removed edit text in the auto mode classifier input.	A number. Env value, else the server setting editRemovalCap, else 3000	Auto mode
CLAUDE_CODE_AUTO_MODE_GIT_STATUS_LIMIT	Undocumented	Sets a truncation limit for git status data in the auto mode classifier.	A number. Env value, else the server setting gitStatusTruncationLimit, else 2000	Auto mode
CLAUDE_CODE_AUTO_MODE_HEARTH_MEMBER_RELAY_ROWS	Undocumented Gated	Turns on rows for posts that a project member relayed in a bound thread, in the auto mode classifier input.	Off by default. Env value, else a feature flag, default off	Auto mode, gated by a feature flag
CLAUDE_CODE_AUTO_MODE_OUTCOME_CODES	Undocumented	Turns on outcome code visibility in the auto mode classifier.	Off by default. Env value, else the server setting outcomeVisibility, default off	Auto mode
CLAUDE_CODE_AUTO_MODE_PRIOR_ASSISTANT_CONTEXT	Undocumented	Turns on prior assistant context in the auto mode classifier input.	Off by default. Env value, else the server setting priorAssistantContext, default off	Auto mode
CLAUDE_CODE_AUTO_MODE_REPO_VISIBILITY	Undocumented	Turns on a repository visibility lookup for the auto mode classifier.	Off by default. Env value, else the server setting repoVisibility, default off	Auto mode
CLAUDE_CODE_AUTO_MODE_SEGMENTED_TRANSCRIPT	Undocumented	Turns on a segmented transcript for the auto mode classifier.	Off by default. Env value, else the server setting segmentedTranscript, default off. Cached per session	Auto mode
CLAUDE_CODE_AUTO_MODE_SERVER	Documented	Controls whether the server reviews auto mode actions. Set to 0 to use the local classifier.	On or off. Unset gives no user choice. Claude Code forwards it to child processes	Auto mode
CLAUDE_CODE_AUTO_MODE_TIER	Undocumented	Any value, even an empty one, switches the auto mode classifier to the strict tier. Claude Code forwards it to child processes.	rawStr. Only presence counts	Auto mode
CLAUDE_CODE_BASH_EDIT_DIFF	Documented	Turns the diff of files changed during a Bash command on or off.	On, off, or unset. Wins over bashEditDiffEnabled. Without either, it is on in auto and bypassPermissions mode only if a further check passes	Bash tool
CLAUDE_CODE_BASH_OUTPUT_AUDIENCE_NOTE	Undocumented	Forces the bash_output_audience_note feature on or off for Bash results with text stdout.	On, off, or unset. Unset leaves the choice to the rollout check	Bash tool
CLAUDE_CODE_BASH_SANDBOX_SHOW_INDICATOR	Undocumented	Shows the name SandboxedBash instead of Bash for commands that run in the sandbox.	On or off, off by default	Bash tool, sandbox
CLAUDE_CODE_BUBBLEWRAP	Undocumented	Tells Claude Code that it runs inside a Bubblewrap sandbox. It also lets --dangerously-skip-permissions run as root.	On or off. Part of the sandbox environment check. IS_SANDBOX=1 has the same effect on the root check	Linux sandbox
CLAUDE_CODE_DISABLE_ADVISOR_TOOL	Documented	Turns off the advisor tool and the /advisor command.	On or off. Checked first in the advisor enable check	First-party and AWS platform. Project env can set it before trust
CLAUDE_CODE_DISABLE_BG_SHELL_PRESSURE_REAP	Documented	Stops Claude Code from ending background shells under critical memory pressure.	On or off. The prompt says it works only from the launch environment	MacOS and Linux
CLAUDE_CODE_DISABLE_DANGEROUS_RM_TIMEOUT	Documented	Turns off the time limit on critical-path removal prompts.	On or off. Forces a feature flag timeout config to disabled	All sessions
CLAUDE_CODE_DISABLE_INLINE_SHELL_RM_PROMPT	Documented	Stops Claude Code from reading bash -c scripts for critical-path removal prompts.	On or off. The check returns null at once when set	All sessions
CLAUDE_CODE_DISABLE_MOUNTED_DRIVE_RM_PROMPT	Undocumented	Turns off the prompt for rm -r on a mounted drive, the folder that holds mounted drives, or a top-level file or folder of a drive. Since 2.1.304 these paths (such as /Volumes, /media, and WSL /mnt/c) get a prompt that permission rules cannot auto-allow.	On or off. The program skips the check when it is set	Bash tool
CLAUDE_CODE_DISABLE_POWERSHELL_CMD_RM_DENY	Documented	Turns off the PowerShell check that denies rd, rmdir, del and erase on system paths.	On or off. Without it a feature flag decides	PowerShell tool
CLAUDE_CODE_DISABLE_SUBSTITUTION_RM_PROMPT	Documented	Turns off the critical-path check for a recursive rm whose target is only command substitution output.	On or off. Checked together with a feature flag	Bash tool
CLAUDE_CODE_DISABLE_WEB_FETCH	Documented	Turns off the WebFetch tool. WebSearch stays on.	On or off. Docs: needs v2.1.285 or later. Also disables the web fetch agent	All sessions
CLAUDE_CODE_DISABLE_WINDOWS_SHELL_LAUNCHER	Documented	Starts PowerShell commands on Windows directly, not through the cmd.exe launcher.	On or off. The launcher also depends on a flag and logs env_opt_out when this is set	Windows PowerShell tool
CLAUDE_CODE_DONT_INHERIT_ENV	Undocumented	Starts the shell snapshot and the spawn-env probe with an empty environment instead of the inherited one.	On or off, off by default	Bash tool shell snapshot setup
CLAUDE_CODE_EMIT_TOOL_USE_SUMMARIES	Undocumented	Sets the emitToolUseSummaries gate that the query loop reads.	On or off, off by default. Passed in the loop gates object next to fastModeEnabled	Query loop, all modes
CLAUDE_CODE_EXECPATH	Undocumented	Gives the shell snapshot function for claude the path of the running binary.	Falls back to the computed install path	Bash tool shell snapshot
CLAUDE_CODE_FILE_READ_MAX_OUTPUT_TOKENS	Documented	Sets the token limit of a file read.	A number. Whole number above 0. Else a built-in default	Read tool
CLAUDE_CODE_FILE_READ_MAX_PDF_PAGES_PER_MESSAGE	Undocumented Gated	Caps the PDF pages that Read tool calls may use in one message.	A number. Whole number of at least 1, plain digits. Active only when a flag enforces the limit	Read tool with PDF files
CLAUDE_CODE_FILE_READ_MAX_PDF_PAGES_PER_TURN	Undocumented Gated	Caps the PDF pages that Read tool calls may use in one turn.	A number. Whole number of at least 1, plain digits. Used only with the per-message cap and an enforcing flag	Read tool with PDF files
CLAUDE_CODE_GIT_BASH_PATH	Documented	Sets the path of the Git Bash executable on Windows.	Text. Must exist and be named bash.exe, sh.exe, bash, or sh. Else warns and auto-detects	Windows
CLAUDE_CODE_GLOB_HIDDEN	Documented	Includes dotfiles in Glob results.	true by default. Set false to exclude them	Glob tool
CLAUDE_CODE_GLOB_NO_IGNORE	Documented	Makes Glob ignore .gitignore rules.	true by default. Set false to respect .gitignore	Glob tool
CLAUDE_CODE_GLOB_TIMEOUT_SECONDS	Documented	Sets the timeout of Glob file discovery in seconds.	A number of seconds, 20 by default and 60 on WSL. Whole number of at least 1	Glob tool
CLAUDE_CODE_INLINE_TOOLS	Undocumented Gated	Turns an inline tools mode on or off. Probe: Adds the beta inline-tools-2026-09-15 to anthropic-beta. See Probes.	On, off, or unset. A false value always turns it off. Off in a CCR_SESSION_PROFILE session	All sessions
CLAUDE_CODE_MAX_TOOL_USE_CONCURRENCY	Documented	Caps how many read-only tools and subagents run in parallel.	A number, 10 by default. Whole number min 1	All sessions
CLAUDE_CODE_MAX_TURNS	Documented	Caps the agentic turns when no --max-turns value is given.	A number. An explicit option wins	Print and SDK modes
CLAUDE_CODE_MAX_WEB_SEARCHES_PER_SESSION	Documented	Caps WebSearch calls per session.	A number, 200 by default. Whole number min 1, digits only	All sessions, WebSearch
CLAUDE_CODE_NANKEEN_KESTREL	Undocumented Gated	Turns on a Windows-only path by env. Nearby text is about the Windows sandbox group. No visible effect in a print-mode probe (Probes).	On or off. Unset follows a feature flag. Always false outside Windows	Windows
CLAUDE_CODE_PERFORCE_MODE	Documented	Turns on Perforce write protection. Edit and Write fail with a p4 edit <file> hint when the file lacks the owner-write bit.	On or off. Parsed as a bool. Also adds a Perforce note to the system context	All file tools
CLAUDE_CODE_POLICY_HELPER_PS1_PATH	Undocumented Gated	Names the PowerShell script that a Windows policy helper runs. The helper script reads it with $env:.	Text. Env var name built into a PowerShell command string. Assumed set by Claude Code for the child	Windows with PowerShell
CLAUDE_CODE_POLICY_HELPER_PSMODULEPATH	Undocumented Gated	Carries the PSModulePath value for the Windows policy helper. The helper script copies it into $env:PSModulePath.	Text. Env var name built into a PowerShell command string. Assumed set by Claude Code for the child	Windows with PowerShell
CLAUDE_CODE_POWERSHELL_RESPECT_EXECUTION_POLICY	Documented	Stops Claude Code from passing -ExecutionPolicy Bypass to PowerShell.	On or off. The branch code was not shown	Windows with PowerShell
CLAUDE_CODE_PWSH_PARSE_TIMEOUT_MS	Undocumented	Sets the timeout of the PowerShell command parse step.	A number of milliseconds, 5000 by default. Whole number in ms above 0. The full wait adds up to 10000 ms more	PowerShell tool
CLAUDE_CODE_QUESTION_EXTENDED	Undocumented	Turns on extended questions in AskUserQuestion. A host sets it from the askUserQuestion.extendedQuestions option.	On or off. Read only for some entrypoints and remote sessions	SDK, remote, and selected entrypoints
CLAUDE_CODE_QUESTION_OPTIONAL_DESCRIPTIONS	Undocumented	Makes option descriptions optional in AskUserQuestion. A host sets it from the askUserQuestion.optionalDescriptions option.	On or off. Read only for some entrypoints and remote sessions	SDK, remote, and selected entrypoints
CLAUDE_CODE_QUESTION_PREVIEW_FORMAT	Undocumented	Sets the preview format of AskUserQuestion. A host sets it from the askUserQuestion.previewFormat option.	Text. Without it markdown is the default for most entrypoints. Not for sdk, desktop, local-agent, or remote	All sessions
CLAUDE_CODE_REPORT_FINDINGS	Undocumented	Gates a findings report mode for review runs. It needs a matching tool in the options and no text or json output. No visible effect in a print-mode probe (Probes).	On or off	Review runs
CLAUDE_CODE_RESTRICTED	Documented	Starts the session in restricted mode like --restricted.	On or off. Other launch paths such as --desktop refuse to run under it	All sessions
CLAUDE_CODE_SANDBOX_LEAVE_DENIES_TO_SRT_WIN	Undocumented	On Windows, stops Claude Code from adding its own deny rules and leaves them to srt-win. The error text warns the sandbox may then fail on a large profile.	On or off. Set it in the launch environment because a settings file cannot set it	Windows sandbox
CLAUDE_CODE_SANDBOX_LEAVE_PARENT_FOLDERS_ALONE	Undocumented	On Windows, stops Claude Code from giving parent folders an entry for the sandbox group. Related log text lists the folders it then skips.	On or off. Only the string use was seen. The exact branch was not read	Windows sandbox
⚠️ CLAUDE_CODE_SANDBOXED	Undocumented	Marks the process as already inside a sandbox. Claude Code then counts the folder as trusted and skips the trust gates.	On or off. Makes the trust check pass and the permission-gate check pass. Also picks the sandbox-time settings path	All sessions. Set by a host or container
CLAUDE_CODE_SCRIPT_CAPS	Documented	Limits how many times named scripts may run per session. It reads a JSON object of substring keys and number limits.	JSON text. JSON object. Bad JSON, an array, or no valid entries turn the caps off	Bash tool. Docs tie it to CLAUDE_CODE_SUBPROCESS_ENV_SCRUB
CLAUDE_CODE_SETTLE_TOUCHED_FILES	Undocumented Gated	Turns on the settle step for touched files after a turn. It needs a feature flag off and a remote or specific build check true.	On or off. Works as an alternative to a feature flag. A second a feature flag adds a step	Turn end in file-reading sessions. gated by a feature flag
CLAUDE_CODE_SHELL	Documented	Sets the shell for Bash tool commands. It accepts a path to bash or zsh. An invalid path falls back to detection.	Text. The path must contain bash or zsh and run. Else Claude Code logs a message and detects a shell from SHELL and PATH	Bash tool
CLAUDE_CODE_SHELL_LAUNCHER_SCRIPT	Undocumented	Passes a launcher script to a PowerShell shell. The wrapper reads it, clears the variable, and runs it with Invoke-Expression.	Text. Set by Claude Code for the PowerShell child. The wrapper sets it to $null before running	PowerShell tool. Set by Claude Code
CLAUDE_CODE_SHELL_PREFIX	Documented	Wraps shell commands that Claude Code starts with a prefix program. Hooks, Bash, status line, and stdio MCP starts use it.	Text. The command is passed to the wrapper as one quoted argument. PowerShell and exec-form hooks skip it	Bash tool, hooks, status line, MCP stdio
CLAUDE_CODE_STRICT_INLINE_SHELL_RM_PROMPT	Undocumented Gated	Restores the strict rm permission prompt for inline shell -c scripts that build rm at run time.	On or off, on by default. Without it a feature flag (default true) picks the relaxed rule. The changelog names this variable	Bash tool permissions
CLAUDE_CODE_SUBPROCESS_ENV_SCRUB	Documented Differs	Strips credentials from the env of subprocesses such as Bash, hooks, and stdio MCP servers.	On, off, or unset. The default depends on the host (see Notes). 1 turns it on and 0 turns it off	Bash, hooks, MCP stdio. Docs omit the GitHub Actions and local-agent defaults
CLAUDE_CODE_TOOL_MEMORY_CGROUP_EXCLUDE	Documented	Lists process kinds that the tool memory cap leaves out. mcp is added unless another rule applies.	A comma-separated list. Without it, a feature flag or a built-in set applies	Linux and WSL
CLAUDE_CODE_TOOL_MEMORY_LIMIT	Documented Differs	Caps memory for tool commands with a cgroup. Docs list 0 and off to turn it off. Code also accepts none.	Text. When unset, a feature flag decides, which docs do not say	Linux and WSL
CLAUDE_CODE_USE_NATIVE_FILE_SEARCH	Documented	Finds commands, subagents, and output styles with Node file APIs and not ripgrep. Docs only. The read site was not re-checked.	On or off. Set 1 to enable	All sessions
CLAUDE_CODE_USE_POWERSHELL_TOOL	Documented	Turns the PowerShell tool on or off. On Windows without Git Bash it is on. With Git Bash the feature flag decides when unset.	On, off, or unset. Non-Windows needs 1. Windows takes 0 or 1	Windows, Linux, macOS, WSL
CLAUDE_CODE_WEB_SEARCH_FAST_ARG	Undocumented Gated	Turns on a fast WebSearch mode with its own description and hint. Env wins over a feature flag.	On, off, or unset. Needs an extra model check to pass	All sessions
CLAUDE_CODE_WEB_SEARCH_REFILLS_PER_HOUR	Documented	Sets how fast the session WebSearch limit refills, in calls per hour.	100 by default. Plain digits. Unset gives 0 when non-interactive, else a feature flag with default 100	All sessions
CLAUDE_CODE_WEBFETCH_CACHE_TTL_MS	Documented	Sets how long WebFetch keeps a fetched URL in cache.	A number of milliseconds, 900000 by default. Plain digits, at least 1. Read once per launch	All sessions
CLAUDE_CODE_WEBFETCH_DEADLINE_MS	Documented	Sets the upper bound on how long WebFetch waits for a download.	A number of milliseconds, 300000 by default. Plain digits, 0 or more. Env value has an upper cap	All sessions
CLAUDE_CODE_WEBSEARCH_CITATIONS	Undocumented	Changes the WebSearch tool prompt so it does not ask for a Sources: list. It also gates a citations code path.	On or off. The second path needs two more checks	All sessions
CLAUDE_ENV_FILE	Documented	Names a shell script that runs before each Bash command in the same shell.	Text. Read and trimmed. Hooks for SessionStart, Setup, CwdChanged, and FileChanged get a path set by Claude Code	Bash tool and hooks
CLAUDE_PID	Documented	Holds the process ID of Claude Code. Child commands use it to find the parent process.	-	-
CLAUDECODE	Documented	Marks a process as running inside Claude Code. Claude Code also reads it to detect a child session and to skip prompt history.	On or off. Set to 1 by Claude Code for shell snapshots, hook and tool subprocesses, and stdio MCP servers	All sessions
ENABLE_TOOL_SEARCH	Documented	Sets MCP tool search mode. Unset defers tools, including behind a custom ANTHROPIC_BASE_URL since 2.1.304. If the gateway answers 400 or 422, Claude Code retries without tool search.	Text. true defer, false upfront, auto or auto:N use a percent threshold. 0 and 100 map to defer and upfront	All sessions. Project env can set it before trust
GCM_INTERACTIVE	Documented	Claude Code sets a default for git child processes so Git Credential Manager does not prompt.	Set by Claude Code when unset in the child env. The default value comes from a table that was not read	Git child processes
GIT_ASKPASS	Documented	Claude Code passes the user value to git child processes. It falls back to a default and then to an empty string.	Text. If unset, SSH_ASKPASS is handed on in its place in one path. Claude Code also sets it	Git child processes. Not set from project env before trust
GIT_CONFIG_COUNT	Documented	Claude Code reads the count and appends its own GIT_CONFIG_KEY_n and GIT_CONFIG_VALUE_n pairs for git child processes.	A number. Parsed as a plain integer string. Also set by Claude Code in a child env	Git child processes. Not set from project env before trust
GIT_CONFIG_GLOBAL	Undocumented	Path of the global git config. Claude Code reads it to find governed git config and sets it in scrubbed child envs.	Set by Claude Code to /dev/null or a sandbox path in some child envs	Git child processes. Not set from project env before trust
GIT_CONFIG_NOSYSTEM	Undocumented	Claude Code sets it to 1 in scrubbed and sandbox child envs so git skips the system config.	Set by Claude Code. No direct read of the user value was seen	Git child processes. Not set from project env before trust
GIT_SSH_COMMAND	Documented	Claude Code uses it, or ssh, as the base of the SSH command for its git calls, and adds -o BatchMode=yes and a connect timeout.	Text. Output is set by Claude Code in the child env. Timeout is 30 in one path and shorter in another	Git clone and fetch. Not set from project env before trust
GIT_TERMINAL_PROMPT	Documented	Claude Code sets it to 0 for git child processes so git never prompts on the terminal.	Set by Claude Code when unset in the child env. In one path the user value is kept	Git child processes. Not set from project env before trust
IS_SANDBOX	Undocumented	Tells Claude Code that it runs in a deliberate sandbox, so root is allowed with --dangerously-skip-permissions.	-	-
JAVA_TOOL_OPTIONS	Undocumented	In the sandbox, Claude Code appends -Dhttps.proxyHost settings to it so Java tools use the sandbox proxy.	-	-
LINES	Documented	Set by Claude Code for hook commands to the terminal row count.	-	-
LOCALAPPDATA	Documented Gated	Used on Windows to find the WindowsApps alias folder and for path checks.	-	-
NoDefaultCurrentDirectoryInExePath	Undocumented	Set by Claude Code to 1 at startup so executable search skips the current directory.	-	-
SHELL	Documented	Names the user shell. Claude Code uses it to find tools, to describe the shell in the prompt, and to run login-shell probes.	Text. Non-empty string. Falls back to /bin/zsh for one probe and to unknown in the prompt text	All sessions, Windows sets it itself
SUDO_GID	Undocumented Gated	Group id of the user who ran sudo. Claude Code uses it with SUDO_UID and SUDO_USER to find the real user when it runs as root.	A number. Integer, digits only, min 0. Used only when the process uid is 0	Linux and macOS as root
SUDO_UID	Undocumented Gated	User id of the user who ran sudo. Claude Code uses it to decide who owns files and git repos when it runs as root.	A number. Integer, digits only, min 0. Used only when the process runs as root	Linux and macOS as root
SUDO_USER	Undocumented Gated	Name of the user who ran sudo. Claude Code checks it against the system and uses it as the real owner when it runs as root.	Text. Non-empty string that must match a safe name pattern. Used only as root	Linux and macOS as root
USE_BUILTIN_RIPGREP	Documented	Set to 0 to use the system rg instead of the bundled one.	On or off. Project settings may set it before trust (allowlist true)	All sessions. Project env can set it before trust

How It Works

The Bash tool starts a shell for each command. Many variables here are read when the command starts. Some variables also pass into the child shell, so a tool you run sees them too. CLAUDE_CODE_SUBPROCESS_ENV_SCRUB strips credentials from the environment of subprocesses such as Bash, hooks, and stdio MCP servers.

Related Pages

• Environment Variables: how Claude Code reads variables and which value wins.
• Tools Reference
• Permissions
• Undocumented Items: every item that only the program shows.

Source: the program (variable names found in the 2.1.304 binary) and the Environment Variables page of the official docs.