pidof

Overview

The pidof command finds process IDs (PIDs) of running programs. It displays the process IDs of named programs.

Syntax

pidof [options] program [program...]

Common Options

Option Description
-s Single shot - return one PID
-x Scripts too - return script PIDs
-o omitpid Omit given PID
-c Only return PIDs in chroot
-n Newest process only
-o Oldest process only
-z Skip zombies
-w Show PIDs with same name

Key Use Cases

  1. Process identification
  2. Script automation
  3. Process monitoring
  4. Service management
  5. System administration

Examples with Explanations

Example 1: Basic Usage

pidof nginx

Find all nginx process IDs

Example 2: Single Process

pidof -s firefox

Find one firefox process ID

Example 3: Omit PID

pidof -o 1234 process_name

Find PIDs except 1234

Understanding Output

  • Space-separated list of PIDs
  • No output if process not found
  • Error messages for:
    • Invalid options
    • Permission issues
    • Process not found

Common Usage Patterns

  1. Kill process:

    kill $(pidof program)

  2. Check if running:

    if pidof program >/dev/null; then echo "Running"; fi

  3. Monitor newest:

    pidof -n program

Performance Analysis

  • Fast execution
  • Minimal system impact
  • Process table lookup
  • Name matching
  • Multiple process handling

Additional Resources

Best Practices

  1. Verify process names
  2. Handle multiple PIDs
  3. Error checking
  4. Script safety
  5. Regular monitoring

Use Cases

  1. Service scripts
  2. Process control
  3. System monitoring
  4. Automation tasks
  5. Dependency checking