How to Use the ps Command in Linux

The real use of the ps command is to know the process details. In fact, along with process details, you would know many other parameters about the process. How many processes are running in a current Session you will get from the below examples.


ps command Linux
ps command Linux

ps Command in Linux

  1. PID (Process Id) - It is the process identification number.
  2. TTY(Terminal name) - associated with this process
  3. TIME(Time) - the format is hh: mm: ss (Hours, Minutes, and Seconds). Cumulated time of that particular process.
  4. CMD (Executable Command name)

I will show you an example, which is very basic, how it appears when you issue the ps command.

Analysis from Output of the ps command
ps command



You May Also Like: PS Command Options in Linux


What is Slave/Master Terminal in Linux

  • The pts/0 is the slave terminal. The pts means pseudo terminal slave. Raise your knowledge by bringing in these quick definitions. LINUX - DIFFERENCE BETWEEN TTY AND PTS.
  • In reality, the terminals are two types. One is ptmx (Master) and pts (Slave).
  • The master terminal holds the details of slaves. Those are pts/0, pts/1, and so on.
  • The slave numbers start from 0, 1, 2, 3...
  • The Psuedo terminals ( Master and Slave) are present in the/dev directory.

Where do They Master/SlaveTerminals Present

 
What You Can See in /dev Directory
Slave and Master


On top of that,  pseudo terminals are two types. BSD style and UNIX98 style. The UNIX98 is the newest style. BSD-style pseudoterminals vs. UNIX 98 pseudoterminals.


ps -eF Command in Linux

The output from ps -eF command.
ps -ef

The Output
  • UID (user id)-it is a root user
  • PID (Process Id)
  • PID (Parent process id)
  • C (Processer utilization). Currently, it is '0'.
  • SZ (size)
  • RSS (Resident set size). Non-swapped physical memory.
  • PSR (Processor number to which this process assigned)
  • STIME (Start Time)
  • TTY (see the above)
  • TIME (Cumulative CPU time)
  • CMD (The executable command details). Here, I have issued ps -eF. You can see this command in the above picture.

Count the Number of Process in Linux


 $ ps | wc -l

4

References

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