Show elapsed (round-trip) time of packets.

$fping -e www.gnu.org
www.gnu.org is alive (301 ms)
$fping -e www.gnu.org
www.gnu.org is alive (302 ms)
$fping -e www.rajagiritech.edu.in
www.rajagiritech.edu.in is alive (62.2 ms)
$fping www.gnu.org
www.gnu.org is alive
$ping www.gnu.org
PING wildebeest.gnu.org (208.118.235.148) 56(84) bytes of data.
64 bytes from wildebeest.gnu.org (208.118.235.148): icmp_seq=1 ttl=49 time=302 ms
64 bytes from wildebeest.gnu.org (208.118.235.148): icmp_seq=2 ttl=49 time=301 ms
64 bytes from wildebeest.gnu.org (208.118.235.148): icmp_seq=3 ttl=49 time=302 ms
^C
--- wildebeest.gnu.org ping statistics ---
4 packets transmitted, 3 received, 25% packet loss, time 3ms
rtt min/avg/max/mdev = 301.312/301.802/302.169/0.360 ms
$ping www.rajagiritech.edu.in
PING rajagiritech.edu.in (202.88.225.163) 56(84) bytes of data.
64 bytes from 163.225.88.202.asianet.co.in (202.88.225.163): icmp_seq=1 ttl=56 time=62.4 ms
64 bytes from 163.225.88.202.asianet.co.in (202.88.225.163): icmp_seq=2 ttl=56 time=62.0 ms
64 bytes from 163.225.88.202.asianet.co.in (202.88.225.163): icmp_seq=3 ttl=56 time=62.4 ms
^C
--- rajagiritech.edu.in ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 4ms
rtt min/avg/max/mdev = 62.038/62.254/62.368/0.254 ms
$

pstree command usage example

$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}]
$

Search for a pattern at the beginning of a line using grep

$ps -e "kworker$"
error: unknown sort specifier

Usage:
 ps [options]

 Try 'ps --help '
  or 'ps --help '
 for additional help text.

For more details see ps(1).
$ps -ef | grep "^daemon"
daemon     639     1  0 May04 ?        00:00:00 /usr/sbin/atd -f
$ps -ef | grep "^rtkit"
rtkit     1245     1  0 May04 ?        00:00:00 /usr/lib/rtkit/rtkit-daemon
$ps -ef | grep "^systemd+"
systemd+   522     1  0 May04 ?        00:00:00 /lib/systemd/systemd-timesyncd
$