Using ps, top and htop is the core method of managing Linux processes. 1. Use ps to view process snapshots, which are suitable for quick inspection, script automation or finding specific processes. For example, ps aux can list all processes, combined with grep to filter specified processes, ps auxf can display process tree structure. 2. Use top for real-time monitoring, provide dynamically updated system resources and process information, sorted by CPU usage by default, and supports interactive operations such as reordering by P or M, killing processes, adjusting priority, and exiting by q. 3. Use htop to get a more friendly enhancement interface. It needs to be installed first. Its advantages include color display, complete command line, resource usage bar, mouse support and F6 sorting, F9 killing process, F7/F8 adjustment priority, F4 search, F10 exit and other convenient functions. According to the scene selection tool: PS is suitable for static viewing and scripting, top is suitable for real-time monitoring of a graphless environment, htop is suitable for interactive in-depth analysis, and mastering the three can fully control the operating status of the system.

Managing processes is a fundamental skill for anyone working with Linux. Whether you're troubleshooting performance issues, monitoring system resources, or just trying to understand what's running on your machine, tools like ps , top , and htop are essential. Here's a practical guide to using each of them effectively.

Understanding Processes in Linux

Before diving into the tools, it helps to know that in Linux, every running program is a process . Each process has a unique Process ID (PID), runs under a user, consumes CPU and memory, and can be in various states (running, sleeping, stopped, etc.). Process management lets you view, monitor, and control these running tasks.

1. ps : View Snapshot of Running Processes

The ps command gives you a static snapshot of current processes. It's lightweight and perfect for scripting or quick checks.

Common ps Commands

• Basic usage

   ps

  Shows processes associated with the current terminal session.

  

• Full listing of all processes

   ps aux

  • a : all users' processes
  • u : display in user-friendly format
  • x : include processes not attached to a terminal

  Output includes:

  • USER : who owns the process
  • PID : process ID
  • %CPU and %MEM : resource usage
  • STAT : process state (eg, S = sleeping, R = running)
  • COMMAND : the command that started the process

• Filter processes by name

   ps aux | grep nginx

  Useful to find specific processes.

• Show process tree

   ps auxf

  Displays processes in a hierarchical tree view, helpful for seeing parent-child relationships.

Pro tip: Combine ps with grep , awk , or sort for powerful one-liners. For example:

 ps aux --sort=-%mem | head -10

Lists the top 10 memory-consuming processes.

2. top : Real-Time Process Monitoring

top provides a dynamic, real-time view of running processes and system resource usage.

Getting Started with top

Run it simply with:

 top

Key Features

• Live updates : Refreshes every few seconds (default: 3 sec)
• System summary at the top:
  • Uptime, load averages
  • CPU usage breakdown (user, system, idle, etc.)
  • Memory and swap usage
• Process list below, sorted by CPU usage by default

Useful Interactive Commands in top

While top is running, press:

• P → Sort by CPU usage
• M → Sort by memory usage
• k → Kill a process (prompts for PID and signal)
• r → Renice a process (change schedule priority)
• q → Quit
• h → Help menu

You can also start top in batch mode for scripting:

 top -b -n 5

Runs in non-interactive mode and exits after 5 iterations.

3. htop : Enhanced, User-Friendly Process Viewer

htop is an improved version of top with a more intuitive interface, color coding, and mouse support. It's not installed by default on most systems, so you may need to install it:

 # Ubuntu/Debian
sudo apt install htop

# CentOS/RHEL
sudo yum install htop
# or on newer versions:
sudo dnf install htop

Why htop Is Better Than top

• Color-coded output for easy reading
• Vertical and horizontal scrolling through processes and command lines
• Visible resource meters (CPU, memory, swap) at the top
• Mouse support for clicking and selecting
• Easier process management (kill, renice) via a visual interface

Key Controls in htop

• Arrow keys : Navigate
• F6 → Sort by field (eg, PID, CPU%, MEM%)
• F9 → Kill selected process
• F7/F8 → Increase/decrease process priority (nice value)
• F4 → Search for a process
• F10 → Quit

Unlike top , htop shows full command lines even if they're long — no more ... truncation.

When to Use Which Tool?

• Use ps when:

  • You need a quick snapshot
  • Writing scripts or automation
  • Looking for a specific process

• Use top when:

  • You want real-time monitoring without installing extra tools
  • Working on a minimum or remote server

• Use htop when:

  • You want a clearer, more interactive view
  • Doing detailed troubleshooting
  • Prefer a more modern, user-friendly interface

Process monitoring doesn't have to be intimidating. With ps , top , and htop , you've got the right tools for every situation — from quick checks to deep system analysis. Get comfortable with all three, and you'll always know what's happening under the hood.

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