fix: verify zsh exists before using it for hook execution #544

ananas-viber · 2026-01-06T13:10:12Z

Summary

Fix hook commands failing silently on systems without zsh installed
Add bash login shell fallback to preserve user PATH when zsh unavailable
Graceful degradation: zsh → bash → default shell

Changes

Refactored findZshPath into generic findShellPath helper function
Added DEFAULT_BASH_PATHS constant and findBashPath() function
Updated executeHookCommand to cascade: zsh -lc → bash -lc → spawn shell:true
Always verify shell exists before using it (fixes the root cause)

Before:

const zshPath = options.zshPath || findZshPath()  // Bug: skips existence check
if (zshPath) {
  finalCommand = `${zshPath} -lc '${escapedCommand}'`
}

After:

const zshPath = findZshPath(options.zshPath)  // Always verifies existence
if (zshPath) {
  finalCommand = `${zshPath} -lc '${escapedCommand}'`
} else {
  const bashPath = findBashPath()  // Fallback preserves login shell PATH
  if (bashPath) {
    finalCommand = `${bashPath} -lc '${escapedCommand}'`
  }
}

Testing

Tested on Ubuntu Linux without zsh installed:

# Stock opencode v1.1.3 + patched oh-my-opencode
opencode run "Add comment to TestComponent.tsx"

# Result: All PreToolUse hooks fire correctly
# - delegation-enforcer.sh: ✅ Captured Edit tool
# - test-hook.sh: ✅ Captured Glob, Read tools

PATH comparison (why bash -lc matters):

Shell	PATH entries
`/bin/sh` (spawn default)	19
`bash -lc`	21
`zsh -lc`	21

The login shell flag (-l) sources user profile files, ensuring custom PATH additions are available for hooks.

Related Issues

No existing issue - discovered during opencode plugin testing.

github-actions · 2026-01-06T13:10:23Z

All contributors have signed the CLA. Thank you! ✅
_{Posted by the CLA Assistant Lite bot.}

ananas-viber · 2026-01-06T13:16:18Z

I have read the CLA Document and I hereby sign the CLA

ananas-viber · 2026-01-06T13:22:25Z

recheck

ananas-viber · 2026-01-06T13:23:31Z

recheck

The `forceZsh` option on Linux/macOS would use a hardcoded zshPath without checking if zsh actually exists on the system. This caused hook commands to fail silently with exit code 127 on systems without zsh installed. Changes: - Always verify zsh exists via findZshPath() before using it - Fall back to bash -lc if zsh not found (preserves login shell PATH) - Fall through to spawn with shell:true if neither found The bash fallback ensures user PATH from .profile/.bashrc is available, which is important for hooks that depend on custom tool locations. Tested with opencode v1.1.3 - PreToolUse hooks now execute correctly on systems without zsh.

ananas-viber · 2026-01-06T13:28:22Z

recheck

greptile-apps · 2026-01-06T13:37:05Z

Greptile Summary

Fixed silent hook execution failures on systems without zsh by verifying shell existence before use. Refactored findZshPath into generic findShellPath helper and added bash fallback (zsh -lc → bash -lc → default shell) to preserve user PATH from login shell profiles.

Key changes:

Created findShellPath() helper that always verifies shell existence via existsSync()
Added DEFAULT_BASH_PATHS constant and findBashPath() function for fallback
Updated executeHookCommand() to cascade through zsh → bash → spawn with shell:true
Moved escapedCommand calculation outside conditional to avoid duplication

Impact:
Hooks now work correctly on Linux systems without zsh installed (previously failed silently). The bash fallback with -lc flag preserves PATH entries from user profile, maintaining parity with zsh behavior.

Confidence Score: 5/5

This PR is safe to merge with minimal risk
The refactoring improves robustness by always verifying shell existence before use, fixing a legitimate bug where hooks would fail silently on systems without zsh. The fallback cascade (zsh → bash → default) is well-designed and preserves existing behavior for systems with zsh while gracefully degrading for those without. Code is clean, follows project conventions, and has been tested on Ubuntu without zsh installed.
No files require special attention

Important Files Changed

Filename	Overview
src/shared/command-executor.ts	Refactored shell path discovery to verify existence before use, added bash fallback when zsh unavailable - fixes silent hook failures on systems without zsh

Sequence Diagram

sequenceDiagram
    participant Hook as Hook Caller
    participant EHC as executeHookCommand()
    participant FZP as findZshPath()
    participant FBP as findBashPath()
    participant FSP as findShellPath()
    participant Spawn as spawn()

    Hook->>EHC: executeHookCommand(cmd, stdin, cwd, {forceZsh: true, zshPath})
    EHC->>EHC: Expand ~ and $CLAUDE_PROJECT_DIR
    
    alt forceZsh enabled
        EHC->>FZP: findZshPath(options.zshPath)
        FZP->>FSP: findShellPath(DEFAULT_ZSH_PATHS, customPath)
        FSP->>FSP: Check customPath exists
        alt customPath exists
            FSP-->>FZP: return customPath
            FZP-->>EHC: return zshPath
            EHC->>EHC: finalCommand = zshPath -lc 'escapedCommand'
        else customPath not found
            FSP->>FSP: Check DEFAULT_ZSH_PATHS
            alt zsh found in defaults
                FSP-->>FZP: return path
                FZP-->>EHC: return zshPath
                EHC->>EHC: finalCommand = zshPath -lc 'escapedCommand'
            else zsh not found
                FSP-->>FZP: return null
                FZP-->>EHC: return null
                EHC->>FBP: findBashPath() [FALLBACK]
                FBP->>FSP: findShellPath(DEFAULT_BASH_PATHS)
                FSP->>FSP: Check DEFAULT_BASH_PATHS
                alt bash found
                    FSP-->>FBP: return bashPath
                    FBP-->>EHC: return bashPath
                    EHC->>EHC: finalCommand = bashPath -lc 'escapedCommand'
                else bash not found
                    FSP-->>FBP: return null
                    FBP-->>EHC: return null
                    EHC->>EHC: finalCommand = expandedCommand [spawn with shell:true]
                end
            end
        end
    else forceZsh disabled
        EHC->>EHC: finalCommand = expandedCommand
    end
    
    EHC->>Spawn: spawn(finalCommand, {shell: true, cwd, env})
    Spawn->>Spawn: Execute hook command
    Spawn-->>EHC: {exitCode, stdout, stderr}
    EHC-->>Hook: return CommandResult

greptile-apps · 2026-01-06T13:37:06Z

Greptile found no issues!

From now on, if a review finishes and we haven't found any issues, we will not post anything, but you can confirm that we reviewed your changes in the status check section.

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cubic-dev-ai

No issues found across 1 file

Confidence score: 5/5

Automated review surfaced no issues in the provided summaries.
No files require special attention.

ananas-viber · 2026-01-06T13:54:00Z

@junhoyeo @code-yeongyu For your attention, would appreciate if you can review.

ananas-viber mentioned this pull request Jan 6, 2026

fix(permission): trigger permission.ask plugin hook in PermissionNext anomalyco/opencode#7077

Closed

ananas-viber force-pushed the fix/zsh-existence-check branch from 0105a06 to c41a4d7 Compare January 6, 2026 13:22

github-actions bot added a commit that referenced this pull request Jan 6, 2026

@ananas-viber has signed the CLA in #544

15571d3

ananas-viber force-pushed the fix/zsh-existence-check branch from c41a4d7 to 09c0122 Compare January 6, 2026 13:23

ananas-viber force-pushed the fix/zsh-existence-check branch from 09c0122 to 53deb91 Compare January 6, 2026 13:28

ananas-viber marked this pull request as ready for review January 6, 2026 13:34

cubic-dev-ai bot reviewed Jan 6, 2026

View reviewed changes

code-yeongyu merged commit d331b48 into code-yeongyu:dev Jan 6, 2026
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fix: verify zsh exists before using it for hook execution #544

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ananas-viber commented Jan 6, 2026 •

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Summary

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Testing

Related Issues

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Greptile Summary

Confidence Score: 5/5

Important Files Changed

Sequence Diagram

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