What
TMPDIR is the environment variable that tells programs where to put temporary files. When a shell command mentions it, Claude Code sets up a separate temporary directory for that command. Before, this happened only when sandboxing was on. Sandboxing is Claude Code's feature for limiting what commands can touch. It now also happens on Windows.
Why
On Windows, commands that rely on TMPDIR now get a temporary folder set up for them, even without sandboxing.
Names in the bundleTMPDIR
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Added since
A small documentation edit on Choose a sandbox environment touched a line naming TMPDIR after this was published.
* The directory where Claude Code writes runtime files. Unless you set [`CLAUDE_CODE_TMPDIR`](/docs/en/env-vars), that directory is:sandbox-environments see the edit
Confirmed since
Anthropic's documentation has since written up TMPDIR, on Error reference.
On macOS and Linux, Claude Code creates a private temp directory at startup, `claude-<uid>` under the system temp directory or the [`CLAUDE_CODE_TMPDIR`](/docs/en/env-vars) override. When the directory can't be created, or an entry already…errors see the edit
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agrees
Anthropic's documentation has since written up TMPDIR, on Error reference.