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: [email protected]/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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