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Understanding the `ps aux` Command in Linux

The ps aux command in Linux provides detailed information about the current processes on the system. It gives an extensive view of the status of processes, including those owned by other users, making it invaluable for system analysis and troubleshooting.

When you run ps aux, you get a tabular output displaying detailed information about each process. Below is a typical output example:

root 1 0.0 0.1 82704 5272 ? Ss Sep16 0:02 /usr/lib/systemd/systemd
jane 1234 0.1 0.2 134560 10520 ? Ss Sep16 0:40 /usr/bin/app1
john 5678 0.0 0.1 108400 5240 pts/0 Ss+ Sep16 0:00 /usr/bin/app2

Deciphering the Output

Here's a breakdown of each column in the output table produced by ps aux:

USERThe owner of the process. It shows the username of the person or system component that started the process.
PIDProcess ID. A unique identifier assigned by the system to this process.
%CPUThe percentage of CPU utilization by the process.
%MEMThe percentage of RAM (memory) utilization by the process.
VSZVirtual Memory Size. The total amount of virtual memory used by the process. Measured in kilobytes (KB).
RSSResident Set Size. The portion of the process’s memory that is held in RAM. Measured in kilobytes (KB).
TTYTerminal Type. Identifies the terminal associated with the process. ? denotes that the process is not associated with any terminal.
STATProcess Status. Indicates the current status of the process, e.g., Running (R), Sleeping (S), Zombie (Z), etc.
STARTStart Time. Shows when the process was started, typically displayed in hh:mm format or in MonDD format if the process was started on a different day.
TIMECumulative CPU Time. Represents the total processor time the process has used since it started.
COMMANDCommand. Shows the command or program associated with the process, along with any command-line options used when the process was started.

Analyzing the Output

Understanding the columns and interpreting the data provided by ps aux helps in assessing the system's status and behavior accurately. Here’s how you might use the output:

  • Identifying Resource-Hungry Processes: By reviewing the %CPU and %MEM columns, you can identify processes that are consuming excessive resources.
  • Troubleshooting Unresponsive Applications: The STAT column can help identify processes that are not responding (D for Uninterruptible Sleep) or have terminated incorrectly (Z for Zombie).
  • Assessing System Load: The TIME and START columns can help assess how long processes have been running and the load on the system over time.


The ps aux command is a powerful tool for monitoring and managing processes in Linux. Understanding each column's meaning and significance allows for effective system analysis, troubleshooting, and optimization, ensuring optimal resource utilization and system stability. By regularly reviewing the output of ps aux, system administrators and users can maintain a healthy and efficient computing environment.

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