ps (process status) displays information about running processes. Shows process IDs, resource usage, and command lines. Essential for system monitoring and process management.
Basic Usage
- ps - List processes in current session
- ps aux - All processes (BSD style)
- ps -ef - All processes (System V style)
- ps -e - All processes
- ps -f - Full format
- ps -u user - User processes
Common Options
- -a - All processes except session leaders
- -e - All processes
- -f - Full format
- -l - Long format
- -u user - User processes
- -p PID - Specific PID
- -C command - Command name
- -x - Include processes without TTY
Output Format
- ps aux - User-oriented format
- ps -ef - Full format
- ps -l - Long format
- ps -o format - Custom format
- ps --forest - Tree format
- ps --sort key - Sort by key
Custom Columns
- ps -o pid,comm,cmd - Custom columns
- ps -o pid,user,%mem,%cpu - Resource usage
- ps -o pid,etime,cmd - Elapsed time
- ps -o pid,ppid,cmd - Parent process
Common Examples
All Processes
ps aux
List all processes with details.
User Processes
ps -u username
Processes for specific user.
Specific Process
ps -p 1234
Information about PID.
Command Search
ps -C firefox
Find process by command.
Tree Format
ps --forest
Show process tree.
Custom Format
ps -o pid,%mem,%cpu,cmd
Custom columns.
Sort by Memory
ps aux --sort=-%mem | head
Top memory consumers.
Sort by CPU
ps aux --sort=-%cpu | head
Top CPU consumers.
Full Command
ps -f -p 1234
Full command line.
Elapsed Time
ps -o pid,etime,cmd
Show how long process has run.
Common Fields
- PID - Process ID
- PPID - Parent Process ID
- USER - Process owner
- %CPU - CPU usage
- %MEM - Memory usage
- VSZ - Virtual memory size
- RSS - Resident set size
- TTY - Terminal
- STAT - Process state
- START - Start time
- TIME - CPU time
- COMMAND - Command line
Tips
- Use ps aux for comprehensive view
- Use --sort to find resource hogs
- Use --forest to see process trees
- Combine with grep to filter
- Use -o for custom output
- Essential for system monitoring
- Check STAT column for process state
- Use with kill for process management