ps — view running processes

💬 "ps command"

• Concept: Shows the list of processes currently running on the server. You need to know the PID to terminate them with kill.
• Output structure: The columns vary depending on the options. By convention, ps aux or ps -ef is commonly used.
• Recommended output for practical use: If you want to see only the columns you need, select and output them like ps -eo pid,user,%mem,cmd.
• PID column: This is the process number. It is the value used when running kill.
• %MEM / %CPU columns: These are memory and CPU usage. Sort in descending order with --sort=-%mem.

3 Essential Command Combinations

• ps aux — View all processes with user, CPU, and memory usage
• ps -ef — View processes including the parent PID (PPID)
• ps aux | grep nginx — View only a specific process

Here are some options worth knowing as well.

• --sort=-%mem — Sort by memory usage in descending order
• For periodic checks, top or htop is convenient.

💬 "Make an example based on a situation beginners often encounter"

Scenario: The process of checking how many web server processes are running.

Step 1: Search for processes

Find processes related to nginx.

ps -ef | grep nginx

Step 2: Count the processes

Count the number of workers.

ps -ef | grep nginx | grep -v grep | wc -l

Step 3: Check the parent process

Check the master process PID.

ps -eo pid,ppid,cmd | grep nginx

Actual Output

This is an example screenshot of viewing processes with ps aux.

!ps command execution result: PID, user, CPU and memory usage, command

Actual production server

Source (HTML): https://games.aidebatehub.com/programs/linux/services/ps.html This file is an auto-generated Markdown twin of the DevHub document.