This command is used to display the parent-child relationship in hierarchical format. The output of this command is quite similar to the output of the ps axjf command and the ps -ef --forest command, as shown in the following command line:

$ pstree

The following screenshot displays the tree hierarchy of a single process with PID using the pstree command:

Display the tree hierarchy of a user's processes by executing the command line given:

$ pstree -p student

On execution of the preceding command, the PIDs assigned to each process are shown in parentheses after each process name.