Exec Resource

The exec: resource runs a shell command and stores its stdout as the resource's output. Use it for system operations, file manipulation, or wrapping CLI tools that don't have a native resource type.

Where it runs

Both workflow mode and agent mode. In workflow mode it executes as a DAG step. In agent mode, the workflow containing this resource runs as a single callable tool.

Basic Usage

# resources/run.yaml
actionId: execResource
name: System Command
exec:
  command: "echo 'Hello, World!'"
  timeout: 30s

Configuration Options

Option	Description
command	The shell command to execute. Supports multiline scripts.
args	List of arguments to pass to the command.
workingDir	The directory in which the command should execute.
env	Map of environment variables specific to this execution.
timeout	Maximum time allowed for execution (e.g., "30s", "1m").

Command Execution

Simple Command

# resources/example.yaml
exec:
  command: "date"
  timeout: 10s

Command with Arguments

# resources/example.yaml
exec:
  command: "your-command"    # The command to execute
  args:                      # Optional: command arguments
    - "--flag"
    - "value"
  workingDir: "/tmp"         # Optional: working directory
  env:                       # Optional: resource-specific env vars
    TEMP_VAR: "value"
  timeout: 30s       # Execution timeout

Multi-line Script

# resources/example.yaml
exec:
  command: |
    echo "Starting process..."
    date
    uname -a
    echo "Done!"
  timeout: 30s

With Interpolation

# resources/example.yaml
exec:
  command: "curl -s https://api.example.com/users/{{ get('user_id') }}"
  timeout: 30s

Examples

System Information

# resources/system-info.yaml
actionId: systemInfo
exec:
  command: |
    echo '{"hostname": "'$(hostname)'", "os": "'$(uname -s)'", "kernel": "'$(uname -r)'", "date": "'$(date -Iseconds)'"}'
  timeout: 10s

File Operations

# resources/file-ops.yaml
actionId: fileOps
exec:
  command: |
    # Create directory
    mkdir -p /tmp/processing

    # Copy uploaded file
    cp "{{ get('file', 'filepath') }}" /tmp/processing/

    # Get file info
    FILE="/tmp/processing/$(basename "{{ get('file', 'filepath') }}")"
    SIZE=$(stat -f%z "$FILE" 2>/dev/null || stat -c%s "$FILE")
    MD5=$(md5sum "$FILE" | cut -d' ' -f1)

    echo "{\"path\": \"$FILE\", \"size\": $SIZE, \"md5\": \"$MD5\"}"
  timeout: 60s

Git Operations

# resources/git-info.yaml
actionId: gitInfo
exec:
  command: |
    cd /app
    BRANCH=$(git rev-parse --abbrev-ref HEAD)
    COMMIT=$(git rev-parse --short HEAD)
    AUTHOR=$(git log -1 --format='%an')
    MESSAGE=$(git log -1 --format='%s')

    echo "{\"branch\": \"$BRANCH\", \"commit\": \"$COMMIT\", \"author\": \"$AUTHOR\", \"message\": \"$MESSAGE\"}"
  timeout: 30s

Process External Tools

# resources/process-image.yaml
actionId: processImage
exec:
  command: |
    INPUT="{{ get('file', 'filepath') }}"
    OUTPUT="/tmp/processed_$(date +%s).jpg"

    # Resize with ImageMagick
    convert "$INPUT" -resize 800x600 -quality 85 "$OUTPUT"

    # Get dimensions
    DIMS=$(identify -format '{"width":%w,"height":%h}' "$OUTPUT")

    echo "{\"output\": \"$OUTPUT\", \"dimensions\": $DIMS}"
  timeout: 120s

FFmpeg Video Processing

# resources/extract-audio.yaml
actionId: extractAudio
exec:
  command: |
    INPUT="{{ get('video', 'filepath') }}"
    OUTPUT="/tmp/audio_$(date +%s).mp3"

    # Extract audio
    ffmpeg -i "$INPUT" -vn -acodec libmp3lame -q:a 2 "$OUTPUT" 2>/dev/null

    # Get duration
    DURATION=$(ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "$OUTPUT")

    echo "{\"audio_file\": \"$OUTPUT\", \"duration_seconds\": $DURATION}"
  timeout: 300s

OCR with Tesseract

# resources/ocr-process.yaml
actionId: ocrProcess
exec:
  command: |
    INPUT="{{ get('file', 'filepath') }}"
    OUTPUT="/tmp/ocr_result.txt"

    # Run OCR
    tesseract "$INPUT" "/tmp/ocr_result" -l eng 2>/dev/null

    # Read result and escape for JSON
    TEXT=$(cat "$OUTPUT" | jq -Rs .)

    echo "{\"text\": $TEXT}"
  timeout: 60s

Docker Operations

# resources/docker-info.yaml
actionId: dockerInfo
exec:
  command: |
    CONTAINERS=$(docker ps --format '{{.Names}}' | wc -l | tr -d ' ')
    IMAGES=$(docker images --format '{{.Repository}}' | wc -l | tr -d ' ')

    echo "{\"running_containers\": $CONTAINERS, \"images\": $IMAGES}"
  timeout: 30s

Curl API Call

# resources/api-call.yaml
actionId: apiCall
exec:
  command: |
    RESPONSE=$(curl -s -X POST \
      -H "Content-Type: application/json" \
      -H "Authorization: Bearer $API_TOKEN" \
      -d '{"query": "{{ get('q') }}"}' \
      https://api.example.com/search)

    echo "$RESPONSE"
  timeout: 30s

Output Handling

The exec resource captures stdout as the result. For structured output, echo JSON:

# resources/example.yaml
exec:
  command: |
    # Process something
    RESULT="success"
    COUNT=42

    # Output JSON
    echo "{\"status\": \"$RESULT\", \"count\": $COUNT}"

Access in other resources:

# resources/example.yaml
requires: [execResource]
apiResponse:
  response:
    result: get('execResource').stdout
    success: get('execResource').success

Environment Variables

Environment variables from workflow settings are available:

# In workflow.yaml
settings:
  agentSettings:
    env:
      API_TOKEN: "secret-token"
      DEBUG: "true"

# In resource
exec:
  command: |
    echo "Token: $API_TOKEN"
    if [ "$DEBUG" = "true" ]; then
      echo "Debug mode enabled"
    fi

Accessing Output Details

Access stdout, stderr, and exit codes from other resources:

# resources/example.yaml
requires: [execResource]
after:
  # Check if command succeeded
  - set('command_success', exec.exitCode('execResource') == 0)
  - set('error_output', exec.stderr('execResource'))

apiResponse:
  response:
    output: get('execResource')  # stdout (default)
    errors: get('error_output')
    success: get('command_success')

See Unified API for details.

Error Handling

Check command exit codes:

# resources/example.yaml
exec:
  command: |
    if ! command -v ffmpeg &> /dev/null; then
      echo '{"error": "ffmpeg not installed"}' >&2  # Write to stderr
      exit 1
    fi

    # Continue with processing...
    echo '{"status": "success"}'
  timeout: 30s

Note: Errors written to stderr are accessible via exec.stderr('resourceId') in other resources.

Installed Packages

Configure OS packages in your workflow:

# workflow.yaml
settings:
  agentSettings:
    osPackages:
      - ffmpeg
      - imagemagick
      - tesseract-ocr
      - jq
      - curl

Best Practices

1. Always set timeouts - Prevent hanging commands
2. Output JSON - Easier to parse in subsequent resources
3. Handle errors - Check for command availability and failures
4. Escape user input - Prevent command injection
5. Use absolute paths - Avoid directory confusion
6. Prefer Python for complex logic - Shell scripts can get unwieldy

Security Notes

When using user input in commands, be careful about command injection:

# Dangerous -- command injection possible
command: "echo {{ get('user_input') }}"

# Safer -- validate input before use
validations:
  check:
    - get('user_input') matches '^[a-zA-Z0-9_-]+$'

See Also

• Python Resource -- complex data processing
• HTTP Client -- API calls (preferred over curl)
• Workflow Configuration -- OS package settings