Command

Execute shell commands and scripts from your ServFlow workflows

The command action allows you to execute shell commands and scripts directly from your workflows. This is useful for system automation, running scripts, processing files, or integrating with command-line tools.

Be cautious when using user input in commands. Always validate and sanitize inputs to prevent command injection attacks.

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command

Executes shell commands and returns their output.

Command

The shell command to execute.

YAML Key	command
Type	string
Required	Yes

The command is executed in the system’s default shell. You can use pipes, redirects, and other shell features.

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Examples

Basic Command

List files in a directory:

actions:
  list_files:
    type: command
    config:
      command: "ls -la /data"
    next: response.success
    fail: response.error

Run a Script

Execute a script file:

actions:
  run_backup:
    type: command
    config:
      command: "/scripts/backup.sh"
    next: response.success
    fail: response.backup_failed

Command with Dynamic Values

Use workflow data in commands (with caution):

actions:
  process_file:
    type: command
    config:
      command: "python /scripts/process.py --file {{ .uploaded_file.path }}"
    next: action.store_result
    fail: response.processing_error

Chained Commands

Use pipes and shell operators:

actions:
  search_logs:
    type: command
    config:
      command: "cat /var/log/app.log | grep ERROR | tail -20"
    next: response.errors

Process Command Output

Use the command output in subsequent actions:

actions:
  get_disk_usage:
    type: command
    config:
      command: "df -h / | tail -1 | awk '{print $5}'"
    next: action.check_threshold

  check_threshold:
    type: javascript
    config:
      script: |
        function servflowRun(vars) {
          const usage = parseInt(vars.get_disk_usage.replace('%', ''));
          return {
            usage: usage,
            alert: usage > 80
          };
        }
    next: conditional.should_alert

Environment Variables

Access environment variables in commands:

actions:
  deploy:
    type: command
    config:
      command: "AWS_PROFILE=production /scripts/deploy.sh {{ param \"version\" }}"
    next: response.deployed
    fail: response.deploy_failed

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Security Considerations

Never directly interpolate user input into commands. This can lead to command injection vulnerabilities.

Unsafe Pattern

# DON'T DO THIS - vulnerable to injection
actions:
  unsafe_command:
    type: command
    config:
      command: "echo {{ param \"user_input\" }}"

Safer Pattern

Validate and sanitize input before use:

actions:
  validate_input:
    type: javascript
    config:
      script: |
        function servflowRun(vars) {
          const input = vars.request_filename || '';
          // Only allow alphanumeric characters and underscores
          const sanitized = input.replace(/[^a-zA-Z0-9_]/g, '');
          return sanitized;
        }
    next: action.safe_command

  safe_command:
    type: command
    config:
      command: "cat /data/{{ .validate_input }}.txt"
    next: response.content

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Common Use Cases

Use Case	Example Command
File operations	cp, mv, rm, mkdir
Data processing	awk, sed, grep, jq
System information	df, free, uptime
Running scripts	python script.py, node script.js, bash script.sh
Git operations	git pull, git log
Container management	docker ps, docker exec

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Next Steps

Memory

Cache command results for reuse.

Transformation

Process command output with JavaScript.

Flow Control

Run multiple commands in parallel.

Actions Overview

Learn the fundamentals of ServFlow actions.