pstree command usage example with process id as first argument

ABOUT pstree

pstree is a Linux command that shows the running processes as a tree. It is used as a more visual alternative to the ps command. The root of the tree is either init or the process with the given pid. It can also be installed in other Unix systems.

TYPICAL COMMANDLINE SESSION

$pidof systemd
1461 1059
$pstree 1461
systemd─┬─(sd-pam)
        ├─at-spi-bus-laun─┬─dbus-daemon
        │                 └─3*[{at-spi-bus-laun}]
        ├─at-spi2-registr───2*[{at-spi2-registr}]
        ├─dbus-daemon
        ├─dconf-service───2*[{dconf-service}]
        ├─evolution-addre─┬─evolution-addre───5*[{evolution-addre}]
        │                 └─4*[{evolution-addre}]
        ├─evolution-calen─┬─evolution-calen───9*[{evolution-calen}]
        │                 └─4*[{evolution-calen}]
        ├─evolution-sourc───3*[{evolution-sourc}]
        ├─gnome-shell-cal───5*[{gnome-shell-cal}]
        ├─gnome-terminal-─┬─bash───pstree
        │                 └─3*[{gnome-terminal-}]
        ├─goa-daemon───4*[{goa-daemon}]
        ├─goa-identity-se───3*[{goa-identity-se}]
        ├─gvfs-afc-volume───3*[{gvfs-afc-volume}]
        ├─gvfs-goa-volume───2*[{gvfs-goa-volume}]
        ├─gvfs-gphoto2-vo───2*[{gvfs-gphoto2-vo}]
        ├─gvfs-mtp-volume───2*[{gvfs-mtp-volume}]
        ├─gvfs-udisks2-vo───2*[{gvfs-udisks2-vo}]
        ├─gvfsd───2*[{gvfsd}]
        ├─gvfsd-fuse───5*[{gvfsd-fuse}]
        ├─gvfsd-metadata───2*[{gvfsd-metadata}]
        ├─mission-control───3*[{mission-control}]
        ├─pulseaudio───2*[{pulseaudio}]
        └─tracker-store───7*[{tracker-store}]
$pstree 1059
systemd─┬─(sd-pam)
        ├─at-spi-bus-laun─┬─dbus-daemon
        │                 └─3*[{at-spi-bus-laun}]
        ├─at-spi2-registr───2*[{at-spi2-registr}]
        ├─dbus-daemon
        └─pulseaudio───2*[{pulseaudio}]
$

$pstree `pidof systemd | awk '{print $2}'`
systemd─┬─(sd-pam)
        ├─at-spi-bus-laun─┬─dbus-daemon
        │                 └─3*[{at-spi-bus-laun}]
        ├─at-spi2-registr───2*[{at-spi2-registr}]
        ├─dbus-daemon
        └─pulseaudio───2*[{pulseaudio}]
$

LINK
https://en.wikipedia.org/wiki/Pstree