Hook execution fails with exit code 127 when project path contains spaces

Bug Description

Claude Code hook execution fails when the project directory path contains
spaces, resulting in "command not found" errors (exit code 127) during
hook execution.

Environment

• OS: Linux (Ubuntu-based)
• Claude Code Version: Latest
• Hook Event: SessionStart (but affects all hook types)

Problem Details

When CLAUDE_PROJECT_DIR contains spaces, Claude Code's hook execution
engine doesn't properly quote the path when executing hook scripts,
causing shell parsing errors.

Example Scenario

• Project Path: /home/user/My Projects/test-project/
• Hook Command: $CLAUDE_PROJECT_DIR/.claude/scripts/example_hook.sh
• Shell Execution: Shell tries to execute /home/user/My as a command with

arguments Projects/test-project/.claude/scripts/example_hook.sh

Steps to Reproduce

1. Create a Claude Code project in a directory path containing spaces:

mkdir -p "/home/user/Test Project/claude-hooks-test"
cd "/home/user/Test Project/claude-hooks-test"

1. Initialize Claude Code project with a simple hook:

{
"hooks": [
{
"event": "SessionStart",
"matcher": {
"all": true
},
"command": "$CLAUDE_PROJECT_DIR/.claude/scripts/test_hook.sh",
"timeoutMs": 5000,
"blocking": false
}
]
}

1. Create the hook script:

mkdir -p .claude/scripts
echo '#!/bin/bash\necho "Hook executed successfully"' >
.claude/scripts/test_hook.sh
chmod +x .claude/scripts/test_hook.sh

1. Start Claude Code session
2. Observe hook failure in logs

Expected Behavior

Hook should execute successfully regardless of spaces in project path.

Actual Behavior

SessionStart:startup
[$CLAUDE_PROJECT_DIR/.claude/scripts/test_hook.sh] failed
with non-blocking status code 127: /bin/sh: 1:
/home/user/Test: not found

Root Cause Analysis

The issue occurs because Claude Code's hook execution engine expands
$CLAUDE_PROJECT_DIR without proper shell quoting:

Current (broken) execution:
# Claude Code internally executes something like:
/home/user/Test Project/claude-hooks-test/.claude/scripts/test_hook.sh

Shell interprets this as:

• Command: /home/user/Test
• Arguments: Project/claude-hooks-test/.claude/scripts/test_hook.sh

Should be quoted as:
"/home/user/Test Project/claude-hooks-test/.claude/scripts/test_hook.sh"

Suggested Fix

In Claude Code's hook execution engine, ensure CLAUDE_PROJECT_DIR
expansion is properly quoted:

# Instead of:
$CLAUDE_PROJECT_DIR/.claude/scripts/hook.sh

# Use:
"$CLAUDE_PROJECT_DIR"/.claude/scripts/hook.sh

Workarounds

1. Move project to path without spaces
2. Use symbolic links:

ln -s "/home/user/Test Project/claude-hooks-test"
"/home/user/claude-test"

1. Use environment variable substitution in hook scripts (though this

doesn't solve the root issue)

Impact

• Prevents Claude Code usage in projects with spaces in paths
• Common on Windows, macOS, and Linux desktop environments where default

directories often contain spaces

• Affects all hook types (SessionStart, PreToolUse, PostToolUse, etc.)

Additional Notes

This is a shell quoting issue in Claude Code's hook execution engine, not
in user-written hook scripts. User scripts that properly quote variables
work fine when the initial command execution succeeds.

---
Priority: Medium (affects usability for common directory naming patterns)
Labels: bug, hooks, shell-execution, path-handling