How do I see all running process in Linux operating systems using command line or GUI options?

You need to use the ps command. It provide information about the currently running processes, including their process identification numbers (PIDs). Both Linux and UNIX support the ps command to display information about all running process. The ps command gives a snapshot of the current processes. If you want a repetitive update of this status, use top, atop, and/or htop command as described below.

 

Apart from ps command, you can also use the following commands to display info about processes on Linux:

  1. top command : Display and update sorted information about processes.
  2. atop : Advanced System & Process Monitor.
  3. htop : Interactive process viewer.

The ps command

Type the following ps command to display all running process:

ps aux | less                                                                                                                                                            

Where,

  • -A: select all processes
  • a: select all processes on a terminal, including those of other users
  • x: select processes without controlling ttys

Task: see every process on the system

ps -A                                                                                                                                                                         
ps -e                                                                                                                                                                        

Task: See every process except those running as root

ps -U root -u root -N                                                                                                                                                 


Task: See process run by user andrej

ps -u andrej                                                                                                                                                               


Task: top command

The top program provides a dynamic real-time view of a running system. Type the top at command prompt:

top                                                                                                                                                                           

Output:

undefined

To quit press q, for help press h.

Task: display a tree of processes

pstree shows running processes as a tree. The tree is rooted at either pid or init if pid is omitted. If a user name is specified, all process trees rooted at processes owned by that user are shown.

pstree                                                                                                                                                                       

Sample outputs:

undefined

Task: Print a process tree using ps

ps -ejH
ps axjf

 

Task: Get info about threads

Type the following command:

ps -eLf
ps axms

 

Task: Get security info

Type the following command:

ps -eo euser,ruser,suser,fuser,f,comm,label
ps axZ
ps -eM


Task: Save Process Snapshot to a file

Type the following command:

top -b -n1 > /tmp/process.log

Or you can email result to yourself:

top -b -n1 | mail -s 'Process snapshot' youremail@youremailprovider.com


Task: Lookup process

Use pgrep command. pgrep looks through the currently running processes and lists the process IDs which matches the selection criteria to screen. For example display firefox process id:

pgrep firefox

Sample outputs:

3356

Following command will list the process called sshd which is owned by a user called root:

pgrep -u root sshd

Say hello to htop and atop

htop is interactive process viewer just like top, but allows to scroll the list vertically and horizontally to see all processes and their full command lines. Tasks related to processes (killing, renicing) can be done without entering their PIDs. To install htop type command:

apt-get install htop

or

yum install htop

Now type the htop command at the shell prompt:

 

htop

Sample outputs:

undefined