How To Show a Processes Tree in Unix

Showing your processes in a hierarchical list is very useful for confirming the relationship between every process running on your system. Today I'd like to show you how you can get tree-like processes lists using various commands.

Showing processes tree with ptree

In Solaris, there's quite a few commands which make the life of any system administrator much easier, they're the process commands (p-commands). One of them which I particularly like is the ptree command which shows you a list of processes.

As you run the command, you get a hierarchical list of all the processes running on your Solaris system, along with process IDs (PIDs). To me, this is a very useful command, because it shows you how exactly each process relates to others in your system.

Here's a fragment of the ptree output:

bash-3.00$ ptree
7     /lib/svc/bin/svc.startd
  250   /usr/lib/saf/sac -t 300
    268   /usr/lib/saf/ttymon
  260   -sh
    5026  -csh
9     /lib/svc/bin/svc.configd
107   /usr/lib/sysevent/syseventd
136   /usr/lib/picl/picld
140   /usr/lib/crypto/kcfd
159   /usr/sbin/nscd
227   /usr/sbin/rpcbind
234   /usr/lib/nfs/statd
235   /usr/sbin/keyserv
236   /usr/lib/netsvc/yp/ypserv -d
  237   rpc.nisd_resolv -F -C 8 -p 1073741824 -t udp
241   /usr/lib/nfs/lockd
247   /usr/lib/netsvc/yp/ypbind
263   /usr/lib/utmpd
286   /usr/sadm/lib/smc/bin/smcboot
  287   /usr/sadm/lib/smc/bin/smcboot
  288   /usr/sadm/lib/smc/bin/smcboot

Processes tree with pstree

In most Linux distributions, you can find a pstree command, very similar to ptree.

That's how you may use it (-p is an option to show PIDs and -l uses long output format):

ubuntu$ pstree -pl
init(1)─┬─NetworkManager(5427)
        ├─NetworkManagerD(5441)
        ├─acpid(5210)
        ├─apache2(6966)─┬─apache2(2890)
        │               ├─apache2(2893)
        │               ├─apache2(7163)
        │               ├─apache2(7165)
        │               ├─apache2(7166)
        │               ├─apache2(7167)
        │               └─apache2(7168)
        ├─atd(6369)
        ├─avahi-daemon(5658)───avahi-daemon(5659)
        ├─bonobo-activati(7816)───{bonobo-activati}(7817)
...

Showing processes tree with ps –forest

ps command found in Linux has a –forest option, which shows you a tree structure of processes.

The best in my experience is to use it like this:

ubuntu$ ps -aef --forest
UID        PID  PPID  C STIME TTY          TIME CMD
...
107       5473     1  0 10037  4600   0 Apr28 ?        00:00:02 /usr/sbin/hald
root      5538  5473  0  5511  1288   0 Apr28 ?        00:00:00  \_ hald-runner
root      5551  5538  0  6038  1284   0 Apr28 ?        00:00:01      \_ hald-addon-input: Listening on /dev/input
107       5566  5538  0  4167   992   1 Apr28 ?        00:00:00      \_ hald-addon-acpi: listening on acpid socke
root      5600  5538  0  6038  1272   1 Apr28 ?        00:00:15      \_ hald-addon-storage: polling /dev/scd0 (ev
root      5476     1  0 10272  2532   0 Apr28 ?        00:00:00 /usr/sbin/console-kit-daemon
root      5627     1  0 12728  1176   1 Apr28 ?        00:00:00 /usr/sbin/sshd
root      9151  5627  0 17536  3032   0 10:53 ?        00:00:00  \_ sshd: greys [priv]
greys     9162  9151  0 17538  1892   1 10:54 ?        00:00:00      \_ sshd: greys@pts/3
greys     9168  9162  0  5231  3820   1 10:54 pts/3    00:00:00          \_ -bash
greys     9584  9168  0  3802  1124   0 11:27 pts/3    00:00:00              \_ ps -aeF --forest

This output is for demonstration purpose only, and so I've taken the first lines of the output out because they weren't serving the purpose of this example very well.

For thins fragment of the output you can see how you get all the vital information about each process. I really like this way of running the ps command.

That's it for today! Do you know any other neat way of looking at processes tree? Let me know!

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  • Nat

    Is there a documented list of what the processes are.
    whatis/man etc doesnt give any information on what the process is. Some are guessable but some are not.

  • Gleb Reys

    Nat,

    There's nothing like this which would come with your Unix system… What processes are you trying to identify, perhaps I or one of the readers can help?

  • siddhant

    hey this was of a real help for me if u can like help me out to create a link btw two computers via unix wud be of great help

  • Sam

    thank u so much for your effort ^_^ , and for those whom using UNIX you can just type " man ps " to get better understanding