gemini

$2a

Symptoms of hung Gemini:

• Process running 20+ minutes with 0% CPU usage

• No network activity

• Process state shows 'S' (sleeping)

Fix hung process:

# Check if hung

ps aux | grep gemini | grep -v grep

# Kill if necessary

pkill -9 -f "gemini.*gemini-3-pro-preview"

Running a Task

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Ask the user (via AskUserQuestion) which model to use in a single prompt. Available models:

• gemini-3-pro-preview ⭐ (flagship model, best for coding & complex reasoning, 35% better at software engineering than 2.5 Pro)

• gemini-3-flash (sub-second latency, distilled from 3 Pro, best for speed-critical tasks)

• gemini-2.5-pro (legacy option, strong all-around performance)

• gemini-2.5-flash (legacy option, cost-efficient with thinking capabilities)

• gemini-2.5-flash-lite (legacy option, fastest processing)

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Select the approval mode based on the task:

• default: Prompt for approval (⚠️ ONLY for interactive terminal sessions)

• auto_edit: Auto-approve edit tools only (for code reviews with suggestions)

• yolo: Auto-approve all tools (✅ REQUIRED for background/automated tasks)

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Assemble the command with appropriate options:

• -m, --model <MODEL> - Model selection

• --approval-mode <default|auto_edit|yolo> - Control tool approval

• -y, --yolo - Alternative to --approval-mode yolo

• -i, --prompt-interactive "prompt" - Execute prompt and continue interactively

• --include-directories <DIR> - Additional directories to include in workspace

• -s, --sandbox - Run in sandbox mode for isolation

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**For background/automated tasks, ALWAYS use --approval-mode yolo** or add timeout wrapper. NEVER use default in non-interactive shells.

-

Run the command and capture the output. For background/automated mode:

# Recommended: Use yolo for background tasks

gemini -m gemini-3-pro-preview --approval-mode yolo "Review this codebase for security issues"

# Or with timeout (5 min limit)

timeout 300 gemini -m gemini-3-pro-preview --approval-mode yolo "Review this codebase"

-

For interactive sessions with an initial prompt:

gemini -m gemini-3-pro-preview -i "Review the authentication system" --approval-mode auto_edit

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After Gemini completes, inform the user: "The Gemini analysis is complete. You can start a new Gemini session for follow-up analysis or continue exploring the findings."

Quick Reference

Use case

Approval mode

Key flags

Background code review

yolo ✅

-m gemini-3-pro-preview --approval-mode yolo

Background analysis

yolo ✅

-m gemini-3-pro-preview --approval-mode yolo

Background with timeout

yolo ✅

timeout 300 gemini -m gemini-3-pro-preview --approval-mode yolo

Interactive code review

default

-m gemini-3-pro-preview --approval-mode default (interactive terminal only)

Code review with auto-edits

auto_edit

-m gemini-3-pro-preview --approval-mode auto_edit

Automated refactoring

yolo

-m gemini-3-pro-preview --approval-mode yolo

Speed-critical background

yolo ✅

-m gemini-3-flash --approval-mode yolo

Cost-optimized background

yolo ✅

-m gemini-2.5-flash --approval-mode yolo

Multi-directory analysis

yolo (if background)

--include-directories <DIR1> --include-directories <DIR2>

Interactive with prompt

auto_edit or default

-i "prompt" --approval-mode <mode>

Model Selection Guide

Model

Best for

Context window

Key features

gemini-3-pro-preview ⭐

Flagship model: Complex reasoning, coding, agentic tasks

1M input / 64k output

Vibe coding, 76.2% SWE-bench, $2-4/M input

gemini-3-flash

Sub-second latency, speed-critical applications

1M input / 64k output

Distilled from 3 Pro, TPU-optimized

gemini-2.5-pro

Legacy: Strong all-around performance

1M input / 65k output

Thinking mode, mature stability

gemini-2.5-flash

Legacy: Cost-efficient, high-volume tasks

1M input / 65k output

Best price ($0.15/M), thinking mode

gemini-2.5-flash-lite

Legacy: Fastest processing, high throughput

1M input / 65k output

Maximum speed, minimal latency

Gemini 3 Advantages: 35% higher accuracy in software engineering, state-of-the-art on SWE-bench (76.2%), GPQA Diamond (91.9%), and WebDev Arena (1487 Elo). Knowledge cutoff: January 2025.

Coming Soon: gemini-3-deep-think for ultra-complex reasoning with enhanced thinking capabilities.

Common Use Cases

Code Review (Background/Automated)

# For background execution (Claude Code, CI/CD, etc.)

gemini -m gemini-3-pro-preview --approval-mode yolo \

  "Perform a comprehensive code review focusing on:

   1. Security vulnerabilities

   2. Performance issues

   3. Code quality and maintainability

   4. Best practices violations"

# With timeout safety (5 minutes)

timeout 300 gemini -m gemini-3-pro-preview --approval-mode yolo \

  "Perform a comprehensive code review..."

Plan Review (Background/Automated)

# For background execution

gemini -m gemini-3-pro-preview --approval-mode yolo \

  "Review this architectural plan for:

   1. Scalability concerns

   2. Missing components

   3. Integration challenges

   4. Alternative approaches"

Big Context Analysis (Background/Automated)

# For background execution

gemini -m gemini-3-pro-preview --approval-mode yolo \

  "Analyze the entire codebase to understand:

   1. Overall architecture

   2. Key patterns and conventions

   3. Potential technical debt

   4. Refactoring opportunities"

Interactive Code Review (Terminal Only)

# ONLY use default mode in interactive terminal

gemini -m gemini-3-pro-preview --approval-mode default \

  "Review the authentication flow for security issues"

Following Up

• Gemini CLI sessions are typically one-shot or interactive. Unlike Codex, there's no built-in resume functionality.

• For follow-up analysis, start a new Gemini session with context from previous findings.

• When proposing follow-up actions, restate the chosen model and approval mode.

• Use AskUserQuestion after each Gemini command to confirm next steps or gather clarifications.

Error Handling

• Stop and report failures whenever gemini --version or a Gemini command exits non-zero.

• Request direction before retrying failed commands.

• Before using high-impact flags (--approval-mode yolo, -y, --sandbox), ask the user for permission using AskUserQuestion unless already granted.

• When output includes warnings or partial results, summarize them and ask how to adjust using AskUserQuestion.

Troubleshooting Hung Gemini Processes

Detection

# Check for hung processes

ps aux | grep -E "gemini.*gemini-3" | grep -v grep

# Look for these symptoms:

# - Process running 20+ minutes

# - CPU usage at 0%

# - Process state 'S' (sleeping)

# - No network connections

Diagnosis

# Get detailed process info

ps -o pid,etime,pcpu,stat,command -p <PID>

# Check network activity

lsof -p <PID> 2>/dev/null | grep -E "(TCP|ESTABLISHED)" | wc -l

# If result is 0, process is hung

Resolution

# Kill hung Gemini processes

pkill -9 -f "gemini.*gemini-3-pro-preview"

# Or kill specific PID

kill -9 <PID>

# Verify cleanup

ps aux | grep gemini | grep -v grep

Prevention

• **ALWAYS use --approval-mode yolo for background/automated tasks**

• Add timeout wrapper for safety: timeout 300 gemini ...

• Never use --approval-mode default in non-interactive shells

• Monitor first run with ps to ensure process completes

Tips for Large Context Processing

• Be specific: Provide clear, structured prompts for what to analyze

• Use include-directories: Explicitly specify all relevant directories

• Choose the right model:

• Use gemini-3-pro-preview for complex reasoning, coding tasks, and maximum analysis quality (recommended default)

• Use gemini-3-flash for speed-critical tasks requiring sub-second response times

• Use gemini-2.5-flash for cost-optimized high-volume processing

• Leverage Gemini 3's strengths: 35% better at software engineering tasks, exceptional at agentic workflows and vibe coding

• Break down complex tasks: Even with large context, structured analysis is more effective

• Save findings: Ask Gemini to output structured reports that can be saved for reference

CLI Version

Requires Gemini CLI v0.16.0 or later for Gemini 3 model support. Check version: gemini --version