System and Third-Party
Claude Code reads many variables that it does not define.
Your system, your terminal, CI services, and other tools own them.
Examples are HOME, PATH, EDITOR, TERM, and ALL_PROXY. Claude Code reads them to find files, pick colors, and detect where it runs.
This page lists 130 variables. You set many of them for your system anyway. Set them in your shell, or in the env key of a settings file.
Example
export EDITOR="code --wait"
claude
Claude Code opens this editor for files, for example for /memory. VISUAL wins over EDITOR.
Variables
The rows are in name order. See Environment Variables for what each column and badge means.
| Variable | Status | What it does | Values and default | Notes |
|---|---|---|---|---|
__ | Undocumented: Only the program shows this item. It can change without notice. | Gives the macOS bundle id of the app that started the process. Claude Code uses it to find the host app and the URL handler. | Text. Non-empty string. com. starts the deep link path | MacOS |
AGENT_ | Undocumented: Only the program shows this item. It can change without notice. | Confirms an Azure Pipelines agent for the terminal color level. | Text. Presence test together with TF_ | All sessions |
ALACRITTY_ | Undocumented: Only the program shows this item. It can change without notice. | Helps Claude Code detect the terminal. A set value counts as an Alacritty terminal in a terminal-feature check and rules out a plain VTE terminal. | On or off. Truthy test only. Read from the env object and from the env of the terminal detector | Terminal UI rendering, all. Not set from project env before trust |
ALACRITTY_ | Undocumented: Only the program shows this item. It can change without notice. | Helps Claude Code detect the terminal. A set value rules out a plain vte- or gnome- guess, because Alacritty sets it. | On or off. Truthy test only, in the terminal detector | Terminal UI rendering, all. Not set from project env before trust |
ALL_ | Documented: An official docs page names this item. | This is a standard proxy variable. Claude Code passes it to git as http. and remote. when it runs git commands. | Text. Read after HTTPS_ and https_, with the lowercase all_ as the last fallback | Git helper commands, all. Not set from project env before trust |
ALLUSERSPROFILE | Undocumented: Only the program shows this item. It can change without notice. | This is a Windows path variable. It is the last fallback for the Program folder when Claude Code builds the Windows Start Menu path. | Text. Order is Program, then PROGRAMDATA, then ALLUSERSPROFILE. Also in a list of Windows path names | Windows. Not set from project env before trust |
ANDROID_ | Undocumented: Only the program shows this item. It can change without notice. | Helps detect the environment. If the path exists, Claude Code records android- in the detected build tools. | Text. Read first, with ANDROID_ as the fallback. Only the path check matters | Environment report, all. Not set from project env before trust |
ANDROID_ | Undocumented: Only the program shows this item. It can change without notice. | Helps detect the environment. It is the fallback for ANDROID_. If the path exists, Claude Code records android- in the detected build tools. | Text. Read only when ANDROID_ is unset | Environment report, all. Not set from project env before trust |
APPDATA | Documented: An official docs page names this item. | This is a Windows path variable. Claude Code uses it for the gcloud config folder, the Alacritty config path, and a Windows path list. | Text. Used on Windows only for gcloud and Alacritty paths | Windows. Not set from project env before trust |
APPVEYOR | Undocumented: Only the program shows this item. It can change without notice. | Names AppVeyor for the terminal color level. | Presence test, only when CI is set. Gives color level 1 | All sessions |
AWS_ | Undocumented: Only the program shows this item. It can change without notice. | Names the AWS runtime. Claude Code uses it to detect aws- and aws- as the deployment environment. The AWS SDK adds it to its user agent. | Compared with AWS_ and AWS_ | All (deployment detection) and AWS SDK calls |
AWS_ | Undocumented: Only the program shows this item. It can change without notice. | Marks an AWS Lambda host. Claude Code reports aws- as the deployment environment when it is set. | Text. Any non-empty value. The AWS SDK also reads it for trace headers | All (deployment detection) |
AWS_ | Undocumented: Only the program shows this item. It can change without notice. | Sets the pager of the AWS CLI. Claude Code lists it among env names that can run a program, for safety checks. | Text. No direct read | Settings env and Bash safety checks |
AZURE_ | Undocumented: Only the program shows this item. It can change without notice. | Names an Azure auth file path. Claude Code lists it among credential file names to protect. | Text. No direct read | Settings env and sandbox credential lists |
AZURE_ | Undocumented: Only the program shows this item. It can change without notice. | Sets the Azure CLI config folder. Claude Code treats it as a credential path to protect, default ~/.. | Text | Sandbox credential deny paths |
AZURE_ | Undocumented: Only the program shows this item. It can change without notice. | Marks an Azure Functions host. Claude Code reports azure- as the deployment environment when it is set. | Any non-empty value | All (deployment detection) |
BASH_ | Documented: An official docs page names this item. | Names the startup file that bash reads. Claude Code treats it as an unsafe inlet and flags it in settings and plugin env. | Claude Code never reads it for its own use | Settings env, plugin env, sandbox checks |
BROWSER | Documented: An official docs page names this item. | Names the command that opens URLs. Claude Code uses it before open on macOS, and the browser setting wins over it. | Text. The browser setting wins over it. On Linux with no display the open step fails with no_ | All sessions |
BUILDKITE | Undocumented: Only the program shows this item. It can change without notice. | Marks a Buildkite CI run. Claude Code uses it for CI detection, deployment detection, and color depth hints. | Text. Any non-empty value counts | All sessions |
C9_ | Undocumented: Only the program shows this item. It can change without notice. | Marks an AWS Cloud9 workspace. Claude Code reports aws- as the environment when it is set. | Any non-empty value. Read directly in deployment detection | All (deployment detection) |
C9_ | Undocumented: Only the program shows this item. It can change without notice. | Marks an AWS Cloud9 workspace. Claude Code reports aws- as the environment when it is set. | Any non-empty value. Read directly in deployment detection | All (deployment detection) |
CDPATH | Undocumented: Only the program shows this item. It can change without notice. | Holds the shell cd search path. Claude Code blanks it in cd helper commands and treats it as an unsafe env name to override. | Text | Bash tool, Git and settings env checks |
CF_ | Undocumented: Only the program shows this item. It can change without notice. | Marks Cloudflare Pages. Claude Code reports cloudflare- as the deployment environment and counts it as a CI signal. | On or off. Truthy value check | All (deployment detection) |
CI | Documented: An official docs page names this item. | Marks a CI run for the terminal color level. | Presence test ("CI" in env), any value counts. A CI vendor variable then picks the level | All sessions |
CI_ | Undocumented: Only the program shows this item. It can change without notice. | Names the CI vendor. Claude Code checks for codeship when it picks the terminal color depth. | Text. Only the value codeship matters | Terminal color detection (all) |
CIRCLECI | Undocumented: Only the program shows this item. It can change without notice. | Marks a CircleCI run. Claude Code uses it for CI detection, deployment detection, and terminal color depth. | Text. Presence counts | All sessions |
CODER | Undocumented: Only the program shows this item. It can change without notice. | Marks a Coder workspace. The environment detector records deployment coder. | - | - |
CODER_ | Undocumented: Only the program shows this item. It can change without notice. | Marks a Coder workspace by name. The environment detector records deployment coder. | Text | - |
CODESPACES | Undocumented: Only the program shows this item. It can change without notice. | Marks GitHub Codespaces. The environment detector records deployment codespaces. | - | - |
COLORTERM | Undocumented: Only the program shows this item. It can change without notice. | Reports terminal color support. truecolor or 24bit means 24-bit color. | - | - |
COLUMNS | Documented: An official docs page names this item. | Gives hook commands the terminal width. | - | - |
COMPUTERNAME | Undocumented: Only the program shows this item. It can change without notice. | Gives the Windows host name. Claude Code uses it as the device name. | - | - |
COMSPEC | Undocumented: Only the program shows this item. It can change without notice. | Gives the Windows command interpreter path. Claude Code uses it as a shell path fallback in environment info. | - | - |
Com | Documented: An official docs page names this item. | Gives the Windows command interpreter path. The terminal opener uses it for the Command Prompt entry. | - | - |
Con | Undocumented: Only the program shows this item. It can change without notice. | Marks ConEmu. Any of the three Con vars turns on terminal progress reporting. | - | - |
Con | Undocumented: Only the program shows this item. It can change without notice. | Marks ConEmu. Any of the three Con vars turns on terminal progress reporting. | - | - |
Con | Undocumented: Only the program shows this item. It can change without notice. | Marks ConEmu. The value {cmd:: also selects Unicode symbols. | - | - |
CONTAINER_ | Undocumented: Only the program shows this item. It can change without notice. | Marks a Windows container. The check turns off the registry sweep. | - | - |
COREPACK_ | Undocumented: Only the program shows this item. It can change without notice. | Claude Code sets it to 0 at startup so that corepack does not edit package.. | - | - |
CURSOR_ | Undocumented: Only the program shows this item. It can change without notice. | Marks the Cursor editor. Claude Code uses it to name the terminal host. | Text | - |
DAYTONA_ | Undocumented: Only the program shows this item. It can change without notice. | Marks a Daytona workspace. The environment detector records deployment daytona. | Text | - |
DENO_ | Undocumented: Only the program shows this item. It can change without notice. | Marks Deno Deploy. The environment detector records deployment deno-. | Text | - |
DEVPOD | Undocumented: Only the program shows this item. It can change without notice. | Marks a DevPod workspace. The environment detector records deployment devpod. | - | - |
DEVPOD_ | Undocumented: Only the program shows this item. It can change without notice. | Marks a DevPod workspace by ID. The environment detector records deployment devpod. | - | - |
DISPLAY | Undocumented: Only the program shows this item. It can change without notice. | Tells Claude Code whether a local display exists on Linux. With no DISPLAY and no WAYLAND_, it treats the browser open as not possible. | Text. Matched against : or unix: forms | Linux. Not set from project env before trust |
DRONE | Undocumented: Only the program shows this item. It can change without notice. | Names Drone CI for the terminal color level. | Presence test, only when CI is set. Gives color level 1 | All sessions |
DYNO | Undocumented: Only the program shows this item. It can change without notice. | Heroku sets it. Environment detection reports the deployment platform as heroku when it is non-empty. | Any non-empty value counts | All sessions. Environment detection only |
EDITOR | Documented: An official docs page names this item. | Names the editor that Claude Code opens for files, for example for /. VISUAL wins over it, and the fallback is the first of code, vi, nano found. | Text. Also sent in environment detection as the editor value | Interactive. Not set from project env before trust |
FLY_ | Undocumented: Only the program shows this item. It can change without notice. | Fly.io sets it. Environment detection reports the platform as fly. when it is non-empty. | Text | All sessions. Environment detection only |
FLY_ | Undocumented: Only the program shows this item. It can change without notice. | Fly.io sets it. Environment detection reports the platform as fly. when it is non-empty. | Text | All sessions. Environment detection only |
FORCE_ | Documented: An official docs page names this item. | Forces the color depth. The Bun runtime maps "", 1, true to 16 colors and 2 to 256 colors. | Text. Untrimmed string | All sessions. Not set from project env before trust |
GH_ | Undocumented: Only the program shows this item. It can change without notice. | Names the gh config directory. Claude Code checks it for hosts. or config. to see if gh has a login. | Text. Falls back to XDG_, then ~/.. Also used in a secrets scan | GitHub features. Not set from project env before trust |
GH_ | Documented: An official docs page names this item. | Names the GitHub host. It picks the enterprise token and is passed to the gh stand-in shim. | Text | GitHub features. Not set from project env before trust |
GH_ | Undocumented: Only the program shows this item. It can change without notice. | Names the repository for gh. Claude Code passes it to the gh shim, which uses a host in it to choose the route. | Text | GitHub features. Not set from project env before trust |
GITEA_ | Undocumented: Only the program shows this item. It can change without notice. | Names Gitea Actions for the terminal color level. | Presence test, only when CI is set. Gives color level 3 in one helper | All sessions |
GITHUB_ | Undocumented: Only the program shows this item. It can change without notice. | Gives the path of the running action. Claude Code protects it in the scrub path list and logs the claude- ref. | A path | GitHub Actions. Not set from project env before trust |
GITHUB_ | Undocumented: Only the program shows this item. It can change without notice. | Marks a GitHub Actions run. It adds run metadata to telemetry and turns on the subprocess env scrub unless you turn that scrub off. | On or off. Truthy parse. CLAUDE_ set to 0, false, no, or off turns the scrub off | GitHub Actions. Not set from project env before trust |
GITHUB_ | Undocumented: Only the program shows this item. It can change without notice. | Gives a user label for a cache diagnostic. It falls back to USER, USERNAME, then the git email name. | Text. The label drops characters outside a-. Claude Code cuts it to 64 characters. Telemetry also reads it in Actions | GitHub Actions. Not set from project env before trust |
GITHUB_ | Undocumented: Only the program shows this item. It can change without notice. | Gives the path of the runner env file. Claude Code adds it to the protected path list of the subprocess scrub. | Claude Code resolves it to a path | GitHub Actions. Not set from project env before trust |
GITHUB_ | Undocumented: Only the program shows this item. It can change without notice. | Gives the path of the event payload file. Claude Code adds it to the protected path list of the subprocess scrub. | A path | GitHub Actions. Not set from project env before trust |
GITHUB_ | Undocumented: Only the program shows this item. It can change without notice. | Gives the path of the workspace. If it differs from the cwd, Claude Code protects its . hooks and config in the scrub path list. | - | GitHub Actions. Not set from project env before trust |
GITLAB_ | Undocumented: Only the program shows this item. It can change without notice. | This is the GitLab CI marker. It appears in CI vendor lists of the Bun runtime and the color support code. | Text. Use is by name in lists. No direct Claude Code read was seen | GitLab CI. Not set from project env before trust |
GITPOD_ | Undocumented: Only the program shows this item. It can change without notice. | Gitpod sets it. Environment detection reports the deployment as gitpod when it is non-empty. | Text | All sessions. Environment detection only |
GNOME_ | Undocumented: Only the program shows this item. It can change without notice. | This is the terminal marker for GNOME Terminal. Environment detection records if it is set. | Presence only | Terminal detection |
GOOGLE_ | Undocumented: Only the program shows this item. It can change without notice. | Marks Google Cloud Workstations. Environment detection reports gcp- when it is set. | Presence check | All sessions. Environment detection only |
HISTFILE | Undocumented: Only the program shows this item. It can change without notice. | Gives the shell history path to a context step that reads the shell history for tool usage. | Text. Passed as the history file input. The step does not run if the home is a network path | Context gathering. Not set from project env before trust |
HOME | Documented: An official docs page names this item. | Holds the home directory. Many paths start from it, such as the config and XDG fallback dirs. | Text. Falls back to the OS home dir | All sessions. Not set from project env before trust |
HOMEDRIVE | Undocumented: Only the program shows this item. It can change without notice. | Holds the Windows home drive. Claude Code sets it in a child env and uses it to expand paths in a Windows lookup. | Set by Claude Code from the home path for a Windows child env | Windows |
HOMEPATH | Undocumented: Only the program shows this item. It can change without notice. | Holds the Windows home path. Claude Code sets it in a child env and uses it to expand paths in a Windows lookup. | Set by Claude Code from the home path for a Windows child env | Windows |
HOMESHARE | Undocumented: Only the program shows this item. It can change without notice. | Holds the Windows network home. Claude Code uses it to expand %HOMESHARE% in a Windows registry lookup. | Text | Windows |
KUBERNETES_ | Undocumented: Only the program shows this item. It can change without notice. | Detects a Kubernetes pod so Claude Code reports a Kubernetes container runtime. | - | - |
NODE_ | Documented: An official docs page names this item. | Claude Code sets production in the env of some helper child processes. It also lists it in env reports. | - | - |
NODE_ | Undocumented: Only the program shows this item. It can change without notice. | Holds Node options. Claude Code adds -- when CLAUDE_ is true. | - | - |
NODE_ | Documented: An official docs page names this item. | Holds the Bun runtime module search path. Claude Code removes it from the env of some helper child processes. | A path | - |
PATH | Documented: An official docs page names this item. | Holds the standard executable search path. Claude Code reads it to find tools and sets it in shell and pwsh child environments. | Text | All sessions. Not set from project env before trust |
PATHEXT | Documented: An official docs page names this item. | Lists the Windows executable extensions. Claude Code uses it when it looks for commands. | Text, . by default. For pwsh child shells Claude Code sets its own value | Windows. Not set from project env before trust |
PIP_ | Undocumented: Only the program shows this item. It can change without notice. | Sets the CA bundle path for pip. Claude Code sets it in the egress-proxy child env. | Text. Also in the sandbox CA list | Sessions with the agent proxy or sandbox. Not set from project env before trust |
PLAYWRIGHT_ | Undocumented: Only the program shows this item. It can change without notice. | Forms part of the key of the local Chrome search for artifact preview. | Text | Local sessions with artifact preview. Not set from project env before trust |
PREFIX | Documented: An official docs page names this item. Gated: Works only behind a flag or a server gate. Works only behind a feature flag or server gate | Gives the Termux install prefix. Claude Code uses $PREFIX/ for daemon and socket paths. | Text. Used only when TERMUX_ is set. Else / | Termux (Android). Not set from project env before trust |
PROGRAMDATA | Undocumented: Only the program shows this item. It can change without notice. Gated: Works only behind a flag or a server gate. Works only behind a feature flag or server gate | Gives the Windows Program folder. Claude Code uses it to find the Start Menu folder and as a protected env name in shell checks. | Text. Looked up as Program, then PROGRAMDATA, then ALLUSERSPROFILE | Windows. Not set from project env before trust |
Program | Documented: An official docs page names this item. Gated: Works only behind a flag or a server gate. Works only behind a feature flag or server gate | Gives the Windows Program folder for the sandbox runtime and the Azure Arc token path. | Text. The sandbox throws Program when it is missing | Windows. Not set from project env before trust |
Program | Documented: An official docs page names this item. Gated: Works only behind a flag or a server gate. Works only behind a feature flag or server gate | Gives the Windows Program Files folder. Claude Code uses it to locate PowerShell and Azure Arc tools. | Text | Windows. Not set from project env before trust |
PROJECT_ | Undocumented: Only the program shows this item. It can change without notice. | Marks the host as Glitch in deployment-environment detection. | Text | All platforms. Not set from project env before trust |
PWD | Documented: An official docs page names this item. | Holds the standard working directory. Claude Code adds it as a session directory when it differs from the original cwd. | Text. Used in startup permission setup and shell-expression checks | All sessions. Not set from project env before trust |
RAILWAY_ | Undocumented: Only the program shows this item. It can change without notice. | Marks the host as Railway in deployment-environment detection. | Text | All platforms. Not set from project env before trust |
RAILWAY_ | Undocumented: Only the program shows this item. It can change without notice. | Marks the host as Railway in deployment-environment detection. | Text | All platforms. Not set from project env before trust |
RENDER | Undocumented: Only the program shows this item. It can change without notice. | Marks the host as Render in deployment-environment detection. | Text | All platforms. Not set from project env before trust |
REPL_ | Undocumented: Only the program shows this item. It can change without notice. | Marks the host as Replit in deployment-environment detection. | Text | All platforms. Not set from project env before trust |
REPL_ | Undocumented: Only the program shows this item. It can change without notice. | Marks the host as Replit in deployment-environment detection. | Text | All platforms. Not set from project env before trust |
REQUESTS_ | Undocumented: Only the program shows this item. It can change without notice. | Sets the CA bundle path for Python requests. Claude Code sets it in the egress-proxy and sandbox child env. | Text. Listed with the other CA variables | Sessions with the agent proxy or sandbox. Not set from project env before trust |
RUNNER_ | Undocumented: Only the program shows this item. It can change without notice. Gated: Works only behind a flag or a server gate. Works only behind a feature flag or server gate | Holds the GitHub Actions runner kind. github- marks a hosted runner in diagnostics. | Text. Read only when GITHUB_ is true | GitHub Actions. Not set from project env before trust |
RUNNER_ | Undocumented: Only the program shows this item. It can change without notice. Gated: Works only behind a flag or a server gate. Works only behind a feature flag or server gate | Holds the GitHub Actions runner OS. Claude Code reports it in telemetry. | Text. Read only when GITHUB_ is true | GitHub Actions. Not set from project env before trust |
SESSIONNAME | Undocumented: Only the program shows this item. It can change without notice. | Holds the Windows console session name. Claude Code only records whether it is set, as telemetry about the terminal. | Text. Any non-empty string. No behavior change | All sessions, telemetry only |
SPACE_ | Undocumented: Only the program shows this item. It can change without notice. | This is a Hugging Face Spaces variable. Claude Code uses it to detect the huggingface- deployment environment for telemetry. | Text. Non-empty string means present | All sessions, telemetry only |
SSH_ | Undocumented: Only the program shows this item. It can change without notice. | Holds the SSH agent socket. The agent proxy tests whether it is unset before it sets up git access. | Text. Non-empty string. Used with GIT_ in a check on the agent proxy git setup | Agent proxy (remote sessions) |
SSH_ | Undocumented: Only the program shows this item. It can change without notice. | Marks an SSH session. Claude Code uses it to decide not to open a browser and for terminal detection. | Text. Non-empty string means SSH. One of SSH_, SSH_ or this on Windows | All sessions |
SSH_ | Undocumented: Only the program shows this item. It can change without notice. | Marks an SSH session. Claude Code treats the terminal as remote and skips opening a browser. | Text. Non-empty string. Sets the terminal ssh flag | All sessions |
SSH_ | Undocumented: Only the program shows this item. It can change without notice. | Marks an SSH session. Used with SSH_ and SSH_ in Windows terminal checks and in the no-browser check. | Text. Non-empty string means present. Also recorded as has in the environment report | All sessions |
STY | Undocumented: Only the program shows this item. It can change without notice. | Holds the GNU screen session id. Claude Code uses it to detect a screen multiplexer. | Text. Non-empty string. Sets the multiplexer to screen when TMUX is not set | All sessions |
SYSTEMROOT | Undocumented: Only the program shows this item. It can change without notice. | Holds the Windows system directory. Claude Code uses it to find powershell. and other Windows tools. | Text. Non-empty string. Falls back to System, then to windir, then to C: | Windows |
System | Documented: An official docs page names this item. | Holds the Windows system directory in its usual mixed case. Claude Code reads it as a fallback and sets it in a clean git env. | Text. Non-empty string. On Windows a sanitized env sets it to C: | Windows |
TERM | Documented: An official docs page names this item. | Holds the terminal type. Claude Code reads it to pick color level, key dialect, and terminal-feature support. | Text. Non-empty string. Names like xterm- or xterm- raise the color level to 3 | All sessions |
TERM_ | Documented: An official docs page names this item. | Holds the terminal program name. Claude Code reads it to detect vscode, i, ghostty, tmux, and others and tune features. | Text. Non-empty string. Used for color level, hyperlinks, clipboard and key support | All sessions |
TERM_ | Undocumented: Only the program shows this item. It can change without notice. | Holds the terminal program version. Claude Code reads the major version to pick a color level for i and a hyperlink check for tmux. | Text. Non-empty string. For example iTerm2 major 3 or later gives true color | All sessions |
TERMINAL_ | Undocumented: Only the program shows this item. It can change without notice. | JetBrains sets it to Jet. Claude Code uses it to detect a JetBrains IDE terminal. | Compared to Jet. On non-macOS it sets the terminal name to pycharm | All sessions, JetBrains terminals |
TERMINATOR_ | Undocumented: Only the program shows this item. It can change without notice. | Holds the Terminator terminal id. Claude Code records only whether it is set, as a telemetry flag. | Text. Non-empty string means present. No behavior change | All sessions, telemetry only |
TF_ | Undocumented: Only the program shows this item. It can change without notice. | Names Azure Pipelines for the terminal color level. | Presence test together with AGENT_. Gives color level 1 in one helper and 4 in another | All sessions |
TILIX_ | Undocumented: Only the program shows this item. It can change without notice. | Holds the Tilix terminal id. Claude Code records only whether it is set, as a telemetry flag. | Text. Non-empty string means present. No behavior change | All sessions, telemetry only |
TMUX | Documented: An official docs page names this item. | Tmux sets it. Claude Code uses it to detect tmux, to find the tmux socket, and to tune colors and features. | Text. Non-empty string. Also gives a true color step down, and blocks some terminal features inside tmux | All sessions |
TMUX_ | Undocumented: Only the program shows this item. It can change without notice. | Tmux sets it. Claude Code uses it to find the current pane when it runs tmux commands. | Text. Non-empty string. Needs TMUX as well | Tmux |
TRAVIS | Undocumented: Only the program shows this item. It can change without notice. | Names Travis CI for the terminal color level. | Presence test, only when CI is set. Gives color level 1 | All sessions |
USER | Documented: An official docs page names this item. | Holds the login name. Claude Code uses it as a fallback for the user name, for example in a browser bridge socket name. | Text. Non-empty string. Read when the OS user lookup fails, then USERNAME, then default | All sessions |
USERNAME | Undocumented: Only the program shows this item. It can change without notice. | Holds the Windows user name. Claude Code uses it as a name fallback and to spot Windows container users. | Text. Non-empty string. Container or Container turns off a registry sweep | Windows |
USERPROFILE | Documented: An official docs page names this item. | Holds the Windows home directory. Claude Code uses it to find Desktop, Documents, Downloads, and IDE lock files, and in WSL path mapping. | Text. Non-empty string. Used on Windows and WSL | Windows and WSL |
UV_ | Undocumented: Only the program shows this item. It can change without notice. | Holds the Node libuv thread pool size. Claude Code only prints it in MCP HTTP debug logs. | Text. Non-empty string. Shown as default when unset | MCP HTTP transport debug |
VERCEL | Undocumented: Only the program shows this item. It can change without notice. | This is a Vercel variable. Claude Code uses it to detect the vercel deployment environment for telemetry. | On or off. Truthy string | All sessions, telemetry only |
VSCODE_ | Undocumented: Only the program shows this item. It can change without notice. | VS Code sets this path. Claude Code checks it to tell Cursor from VS Code and to find remote VS Code servers. | Text. Non-empty string. A path with cursor means Cursor | VS Code and Cursor terminals |
VTE_ | Undocumented: Only the program shows this item. It can change without notice. | Holds the VTE terminal version. Claude Code uses it for terminal bug workarounds and hyperlink support. | A number. A value under 5300 gets a workaround for unknown sequence printing. 4400 or more enables a feature | VTE terminals |
WAYLAND_ | Undocumented: Only the program shows this item. It can change without notice. | Holds the Wayland display name. Claude Code uses it to detect whether a local display exists, and to pick a clipboard tool. | Text. Non-empty string. With no DISPLAY and no WAYLAND_ on Linux, it takes no browser or GUI path | Linux |
WEBSITE_ | Undocumented: Only the program shows this item. It can change without notice. | This is an Azure App Service variable. Claude Code uses it to detect the azure- environment for telemetry. | Text. Non-empty string means present | All sessions, telemetry only |
WEBSITE_ | Undocumented: Only the program shows this item. It can change without notice. | This is an Azure App Service variable. Claude Code uses it to detect the azure- environment for telemetry. | Text. Non-empty string means present | All sessions, telemetry only |
WEZTERM_ | Undocumented: Only the program shows this item. It can change without notice. | Holds the WezTerm pane id. Claude Code uses it to exclude WezTerm when it detects a VTE-based terminal. | Text. Non-empty string. Used as a presence check only | All sessions |
WINDIR | Undocumented: Only the program shows this item. It can change without notice. | Holds the Windows directory. Claude Code reads it once at load to build the explorer. path for a Windows app filter. | Lowercased with a trailing backslash. Also a fallback for powershell. path | Windows |
WSL_ | Undocumented: Only the program shows this item. It can change without notice. | Holds the WSL distro name. Claude Code uses it to detect WSL and to match IDE workspace paths. | Text. Non-empty string. Either this or WSL_ on Linux sets the platform to wsl | WSL |
WSL_ | Undocumented: Only the program shows this item. It can change without notice. | Holds the WSL interop socket. Claude Code uses it to detect WSL. | Text. Non-empty string. Either this or WSL_ on Linux sets the platform to wsl | WSL |
WT_ | Undocumented: Only the program shows this item. It can change without notice. | Holds the Windows Terminal session id. Claude Code uses it to detect Windows Terminal for key and link support. | Text. Non-empty string. Enables hyperlinks and some features | Windows Terminal |
XTERM_ | Undocumented: Only the program shows this item. It can change without notice. | Holds the xterm version. Claude Code uses it to tell xterm from a VTE terminal and as a telemetry flag. | Text. Non-empty string. Presence check only | All sessions |
ZDOTDIR | Documented: An official docs page names this item. | Holds the zsh config directory. Claude Code uses it to find the zsh rc files when it checks for a claude alias. | Text. Non-empty string. Falls back to the home dir | Zsh users |
ZED_ | Undocumented: Only the program shows this item. It can change without notice. | This is the Zed terminal marker. Claude Code uses it to detect the Zed terminal for hyperlink and feature support. | Text. Non-empty string. Presence check only | Zed terminal |
ZELLIJ | Undocumented: Only the program shows this item. It can change without notice. | This is the Zellij marker. Claude Code uses it to detect the zellij multiplexer. | Any value other than undefined. Turns off some terminal features | Zellij |
How It Works
Many rows here are detection names. Claude Code checks whether a name is set to learn the terminal, CI service, or host. For example, TRAVIS or GITLAB_CI tell it that it runs in CI, which affects the terminal color level.
You rarely set these by hand. Set one only to fake or hide a detection result.
Related Pages
- Environment Variables: how Claude Code reads variables and which value wins.
- Bundled Libraries
- Network and Proxy
- UI and Terminal
- Undocumented Items: every item that only the program shows.
Source: the program (variable names found in the 2.1.312 binary) and the Environment Variables page of the official docs.