The process-tree script presented in this chapter does exactly what its name suggests: it prints out the names of some or all of the currently running processes that are present in the process table, displaying the parent/child relationships that exist among them in the form of a visual tree. There is an implementation of this functionality on some versions of Solaris (
ptree) and on all flavors of Linux (
pstree). These have proved very valuable to me for finding the root of a process group quickly, especially when that part of the process tree needs to be shut down.
There are some UNIX-based operating systems that don't have this functionality, such as HP-UX; hence the reason for this script. Along the way, this script ...