[BUG] Background tasks ignore $TMPDIR and hardcode /tmp/claude/

[Butanium]

Description

Claude Code's background task system ignores the $TMPDIR environment variable and hardcodes /tmp/claude/ for task management, causing permission denied errors when /tmp is not writable by the user.

Steps to Reproduce

1. Have $TMPDIR set to a valid, writable directory (e.g., /run/user/$(id -u))
2. Ensure /tmp is not writable by the current user
3. Run a background task in Claude Code (e.g., run_in_background: true on a Bash command)

Expected Behavior

Claude Code should respect $TMPDIR and create its task directory there.

Actual Behavior

Claude Code ignores $TMPDIR and attempts to create /tmp/claude/<workspace-path>/tasks, resulting in:

EACCES: permission denied, mkdir '/tmp/claude/-mnt-nw-home-c-dumas-research-libs-nnsight/tasks'

Environment

• OS: Linux 6.8.0-60-generic (Ubuntu)
• TMPDIR: /run/user/2011 (set and valid)
• Claude Code version: Latest

Notes

This is distinct from existing issues like #10194 (TMPDIR pointing to non-existent directory) and #14799 (EXDEV with tmpfs). In this case, $TMPDIR is correctly set to a valid, writable directory, but Claude Code completely ignores it for the background task system.

[Butanium]

see also https://github.com/anthropics/claude-code/issues/15637 for same issue on a diff platform

[salviz]

Additional Finding: Termux Path Sanitization Variant

A related issue has been discovered on Termux (Android) that stems from the same root cause. See #15801.

Termux-Specific Problem: The path sanitization logic (replacing / with -) creates invalid paths on systems with deeply nested HOME directories.

Example:

• HOME: `/data/data/com.termux/files/home`
• Sanitized: `-data-data-com-termux-files-home`
• Invalid Path: `/tmp/claude/-data-data-com-termux-files-home/tasks`

Both issues (#15700 and #15801) would be fixed by using XDG Base Directory Specification (`~/.cache/claude/tasks`) or properly hashing the HOME path instead of character replacement.

Platform: Termux on Android ARM64 Reporter: User with TalkBack accessibility needs

[Butanium]

@claude any fix you'd suggest for this?

[Lectem]

It seems this propagated to agents, can't run them this morning, most likely due to 2.1.0

[andersglindstrom]

To work around this problem, I did this:

:; claude --version
2.1.1 (Claude Code)

This is the version with the bug.

First thing, disable auto update by adding this to ~/.claude/settings.json:

  "env": {
    "DISABLE_AUTOUPDATER": "1"
  }

If you are still on version 2.0.76 you're good.

If you are on 2.1.1 then you also have to do this:

:; npm install @anthropic-ai/[email protected]

And then verify:

:; claude --version
2.0.76 (Claude Code)

[Butanium]

@andersglindstrom this solution was described in the termux post and worked for me: sed -i "s|/tmp/claude|/data/data/com.{CUSTOM_TMP_PATH}|g" cli.js

I asked Claude to find cli.js referencing the issue and I have a custom command like this that I run after each update

[Lectem]

I can confirm replacing the hardcoded path with a usable one fixed subagents.

[Lectem]

2.1.5 seems to have made things worse and patch no longer works.

[Butanium]

@Lectem we investigated this and there is now a fix: The fix is working (directories exist). What exactly is the issue you're experiencing? Can you describe what "doesn't work anymore" means - is there an error message?

Let me also check if there are newer patterns in the code that might need patching:

● Bash(grep -c 'CLAUDE_CODE_TMPDIR' "/mnt/nw/home/c.dumas/.nvm/versions/node/v22.17.0/lib/node_modules/@anthropic-ai/claude-code/cli.js") ⎿ 3

● Good news - newer versions of Claude Code support CLAUDE_CODE_TMPDIR environment variable! Instead of patching the binary, you can now use this cleaner approach:

export CLAUDE_CODE_TMPDIR=/run/user/$(id -u)

Add this to your ~/.bashrc or ~/.zshrc and it should work without needing to patch cli.js after each update.

What specific error are you seeing? That will help me determine if there's another issue at play.

[Lectem]

I was getting such messages:

Bash(rm -rf build && CMAKE_C_COMPILER_LAUNCHER=ccache CMAKE_CXX_COMPILER_LAUNCHER=ccache cmake -B build -G Ninja 2>&1 | tail -20) ⎿  Error: EACCES: permission denied, mkdir '/tmp/claude/-data-data-com-termux-files-h ome-code-myproject/tasks'

And the workaround mentioned here https://github.com/anthropics/claude-code/issues/15700#issuecomment-3723281340 would make Claude code freeze after a few seconds. (it could also be another bug of 2.1.5 I guess)

In any case it seems that CLAUDE_CODE_TMPDIR works, this should be documented or set properly to read $TMPDIR by default.