ps

Additional Notes

ps shows a snapshot of running processes. It helps you find process IDs, owners, commands, CPU usage, memory usage, and process state.

Unlike top or htop, ps does not keep updating. It prints a point-in-time view.

Syntax

ps [options]

Different Unix styles exist, so you will see options with and without dashes.

Parameters

• options: Flags that change how ps behaves.
• pid: Process ID to inspect or signal.
• job: Shell job ID such as %1 when job control is involved.
• command: Command name or pattern to match.

Common Options

• aux: Show processes for all users with useful details.
• -ef: Show all processes in full-format listing.
• -u USER: Show processes for a user.
• -p PID: Show a specific process ID.
• -o FORMAT: Choose output columns.
• --sort FIELD: Sort output.
• f: Show process tree style in some formats.

Useful Columns

• USER: Process owner.
• PID: Process ID.
• %CPU: CPU usage.
• %MEM: Memory usage.
• VSZ: Virtual memory size.
• RSS: Resident memory in RAM.
• TTY: Terminal associated with the process.
• STAT: Process state.
• START: Start time.
• TIME: CPU time used.
• COMMAND: Command that started the process.

Examples

ps

Show processes attached to the current terminal.

ps aux

Show a broad list of running processes.

ps -ef

Show all processes in full format.

ps aux | grep nginx

Find processes related to nginx.

ps -p 1234 -o pid,ppid,user,stat,cmd

Show selected columns for one process.

ps aux --sort=-%mem | head

Show memory-heavy processes.

ps aux --sort=-%cpu | head

Show CPU-heavy processes.

Practical Notes

• Use ps aux for a quick full-system view.
• Use pgrep when you only need process IDs by name.
• Use kill PID to signal a process after confirming the PID.
• Process names can be misleading; inspect the full command when possible.
• For live monitoring, use top or htop.