ps - Process Status
Summary
The ps command displays information about active processes. It allows you to monitor and manage running programs on your system.
Introduction
The ps command, short for "process status," is a fundamental utility in Linux for monitoring and managing processes. It provides a snapshot of currently running processes, including their process IDs (PIDs), resource usage, and other relevant information. This command is invaluable for system administrators and developers who need to diagnose performance issues, identify resource hogs, or simply understand what's happening on their system.
Use case and Examples
Listing all processes for the current user
This command displays processes owned by the current user in the current terminal. It shows information such as PID, TTY, STAT, TIME, and COMMAND.Listing all processes on the system
The-A option displays all processes running on the system, regardless of the user who owns them. This provides a comprehensive overview of system activity. Listing processes with full command and user
The-ef options provide a full listing of processes. -e selects all processes and -f generates a full listing. The output includes the username, PID, PPID, CPU usage, start time, terminal, status, and the command with its arguments. Listing processes with a specific user
Replaceusername with the actual username to display only processes owned by that user. Displaying a process and its children as a tree
This displays the relationship between processes in a tree-like format.-a selects all processes, -x includes processes without controlling terminals and -jf displays in tree format. Commonly used flags
| Flag | Description | Example |
|---|---|---|
-A | Select all processes. Identical to -e. | ps -A |
-e | Select all processes. | ps -e |
-f | Generate a full listing. | ps -f |
-u | Select processes by effective user ID. | ps -u username |
-p | Select processes by process ID (PID). | ps -p 1234 |
-o | Specify user-defined output format. Allows you to customize which columns are displayed. | ps -o pid,user,comm |
-aux | Display all processes with user and memory usage information. This option is a combination of BSD-style options. | ps aux |
-l | Display long format output | ps -l |
-j | Jobs format | ps -j |