Process Management with the Linux ps aux Command

What ps aux does

ps shows a snapshot of running processes. The letters mean:

• a shows processes of all users, not only yours.
• u shows detailed information, including the owner.
• x includes processes without a controlling terminal, such as services.

ps aux

The columns

• USER is the owner of the process.
• PID is the process ID.
• %CPU is the share of CPU the process uses.
• %MEM is the share of RAM it uses.
• VSZ is the virtual memory size in KB.
• RSS is the physical memory it uses in KB.
• TTY is the terminal. ? means there is none.
• STAT is the state: R running, S sleeping, D waiting for disk, Z zombie (defunct), T stopped. Extra letters like s (session leader), l (multi-threaded) or + (foreground) follow it.
• START is when it started.
• TIME is the CPU time used.
• COMMAND is the command that started it.

Useful variations

Show a process tree:

ps auxf

Show the processes of one user:

ps -u username

Show one process by ID:

ps -p 2600 -o pid,user,%cpu,%mem,cmd

Sort by CPU use (lowest to highest, add a - for highest first):

ps aux --sort=-%cpu

Choose your own columns:

ps -eo pid,user,%cpu,cmd

Show the top 5 CPU users:

ps aux --sort=-%cpu | head -n 6

(The first line is the header.)

Find zombie processes:

ps aux | grep defunct

Find a process by name or PID:

ps aux | grep 2600

Tips

• The command grep also finds itself. Use pgrep name or ps aux | grep [n]ginx to avoid that line.
• top and htop show the same data live.
• To stop a process, use kill PID.

Quick recap

• ps aux lists all processes.
• Use --sort, -u and -p to narrow the list.