How to list processes for non root users

Introduction

In the complex world of Linux system administration, understanding how to list processes for non-root users is a crucial skill. This tutorial provides comprehensive insights into process management techniques, enabling users to effectively view and monitor system processes without elevated permissions.

Skills Graph

%%%%{init: {'theme':'neutral'}}%%%% flowchart RL linux(("`Linux`")) -.-> linux/ProcessManagementandControlGroup(["`Process Management and Control`"]) linux(("`Linux`")) -.-> linux/UserandGroupManagementGroup(["`User and Group Management`"]) linux(("`Linux`")) -.-> linux/SystemInformationandMonitoringGroup(["`System Information and Monitoring`"]) linux/ProcessManagementandControlGroup -.-> linux/jobs("`Job Managing`") linux/UserandGroupManagementGroup -.-> linux/whoami("`User Identifying`") linux/SystemInformationandMonitoringGroup -.-> linux/ps("`Process Displaying`") linux/SystemInformationandMonitoringGroup -.-> linux/top("`Task Displaying`") linux/ProcessManagementandControlGroup -.-> linux/kill("`Process Terminating`") linux/ProcessManagementandControlGroup -.-> linux/killall("`Multi-Process Killing`") linux/ProcessManagementandControlGroup -.-> linux/bg_process("`Background Management`") subgraph Lab Skills linux/jobs -.-> lab-419058{{"`How to list processes for non root users`"}} linux/whoami -.-> lab-419058{{"`How to list processes for non root users`"}} linux/ps -.-> lab-419058{{"`How to list processes for non root users`"}} linux/top -.-> lab-419058{{"`How to list processes for non root users`"}} linux/kill -.-> lab-419058{{"`How to list processes for non root users`"}} linux/killall -.-> lab-419058{{"`How to list processes for non root users`"}} linux/bg_process -.-> lab-419058{{"`How to list processes for non root users`"}} end

Linux Process Basics

What is a Process?

A process is a running instance of a computer program. In Linux, every command you execute creates a process that consumes system resources such as CPU, memory, and disk space. Each process has a unique Process ID (PID) assigned by the Linux kernel.

Process States

Linux processes can exist in different states during their lifecycle:

State	Description
Running	Currently executing on the CPU
Sleeping	Waiting for a system resource or event
Stopped	Paused and can be resumed
Zombie	Completed but not yet removed from process table

Process Hierarchy

graph TD A[Init Process - PID 1] --> B[Parent Process] B --> C[Child Process 1] B --> D[Child Process 2]

In Linux, all processes are descendants of the init process (PID 1), creating a tree-like process hierarchy.

Basic Process Attributes

Process ID (PID)
Parent Process ID (PPID)
User ID (UID)
Priority
Memory usage
CPU usage

Process Creation Methods

Forking: Creating an exact copy of the parent process
Executing: Replacing the current process with a new program
System calls like fork() and exec()

Example: Simple Process Information

## Display current process ID
echo $$

## List basic process information
ps aux

LabEx recommends understanding these fundamental concepts to effectively manage Linux processes.

Process Listing Methods

Common Linux Process Listing Commands

1. ps Command

The ps command provides detailed process information with various options:

## List all processes
ps aux

## List processes for current user
ps u

## List processes in detailed format
ps -ef

2. Top Command

Interactive real-time process viewer with system resource information:

## Launch top command
top

## Show top processes sorted by CPU usage
top -o %CPU

## Show top processes sorted by memory usage
top -o %MEM

Process Listing Options Comparison

Command	Real-time	Detailed Info	Sorting Capability
ps	No	High	Limited
top	Yes	Moderate	Excellent
htop	Yes	High	Advanced

Advanced Process Filtering

## List processes by specific user
ps -u username

## Find processes by name
pgrep process_name

## Show process tree
pstree

Process Listing Workflow

graph TD A[Start Process Listing] --> B{Choose Method} B --> |Static List| C[ps Command] B --> |Real-time Monitoring| D[top Command] C --> E[Filter/Sort Results] D --> F[Interactive Monitoring]

Performance Considerations

ps is lightweight and quick
top consumes more resources
Use appropriate command based on requirement

LabEx recommends mastering these process listing techniques for effective Linux system management.

Non-Root User Techniques

User Process Visibility Limitations

Non-root users have restricted access to system processes. Understanding these limitations is crucial for effective process management.

Permitted Process Viewing Methods

1. Basic User Process Commands

## List own processes
ps

## List processes for current user
ps -u $USER

## Show user-specific processes
ps aux | grep $USER

2. Permissions-Based Filtering

## View processes owned by current user
pgrep -u $USER

## List processes with detailed user information
ps -elf | grep $USER

Permission Levels Comparison

Permission Level	Visible Processes	Detailed Information
Non-Root User	Own Processes	Limited
Root User	All Processes	Complete

Advanced Non-Root Techniques

Using /proc Filesystem

## List process information from /proc
ls /proc | grep ^[0-9]

## View specific process details
cat /proc/[PID]/status

Process Visibility Workflow

graph TD A[User Initiates Process List] --> B{Authentication} B --> |Non-Root| C[Limited Process View] B --> |Root| D[Complete Process View] C --> E[Filter Personal Processes] D --> F[Unrestricted Access]

Security Considerations

Non-root users can only view their own processes
Kernel provides process isolation
Use sudo for elevated permissions when necessary

Best Practices

Use user-specific commands
Understand permission constraints
Leverage /proc filesystem
Use pgrep and ps with user filters

LabEx recommends mastering these techniques for effective process management in restricted environments.

Summary

By mastering these Linux process listing techniques, non-root users can gain valuable insights into system performance, resource utilization, and running applications. The methods discussed offer flexible and powerful approaches to understanding the dynamic landscape of system processes across different Linux environments.