pstree is a small program that shows the process listing (ps) as a tree (as the name implies...). It has several options to make selection criteria and to change the output style.
It should compile under most Un*xes, tested are AIX, Linux, HP-UX, A/UX, SunOS, Solaris, (Free|Open|Net)BSD, MacOSX/Darwin/macOS, and many others.
Under AIX & Linux, pstree directly reads the process table using getproc()/getuser() or the /proc file system. Under all other Un*xes, pstree reads the output of /bin/ps.
Take an ANSI C compiler, e.g., gcc, and just enter
$ [g]cc -O -o pstree pstree.c
Alternatively, enter make.
Put the binary pstree into appropriate bindir, e.g., /usr/local/bin.
Optionally, put the manpage pstree.1 to, e.g., /usr/local/share/man/man1.
For changes up to v2.40, see end of pstree.c.
$ ./pstree -?
pstree $Revision: 2.40 $ by Fred Hucht (C) 1992-2022
EMail: fred AT thp.uni-due.de
Usage: pstree [-f file] [-g n] [-l n] [-u user] [-U] [-s string] [-p pid] [-w] [pid ...]
-f file read input from <file> (- is stdin) instead of running
"ps -eo uid,pid,ppid,pgid,args"
-g n use graphics chars for tree. n=1: IBM-850, n=2: VT100, n=3: UTF-8
-l n print tree to n level deep
-u user show only branches containing processes of <user>
-U don't show branches containing only root processes
-s string show only branches containing process with <string> in commandline
-p pid show only branches containing process <pid>
-w wide output, not truncated to window width
pid ... process ids to start from, default is 1 (probably init)
Process group leaders are marked with '='.
pstree started as a shell script back in the 90s, the first C version is from 1992. Since 1994, the source was managed using RCS. Since 2022, it lives here on GitHub.
pstree was formerly available under
ftp://ftp.thp.uni-due.de/pub/source/(server down)http://www.thp.uni-due.de/pstree/(server down)
Have fun, Fred