A - PUB,RR,SUB     (bind to address)
a
B
b
C - SUB            (message count)
c - PUB,RR,SUB     (clean session)
D - PUB,RR,SUB     (properties)
d - PUB,RR,SUB     (debug log)
E - SUB            (exit after subscribe)
e - RR             (response topic)
F - RR,SUB         (output format)
f - PUB,RR         (file input)
G
g
H
h - PUB,RR,SUB     (host)
I - PUB,RR,SUB     (client id prefix)
i - PUB,RR,SUB     (client id)
J
j
K
k - PUB,RR,SUB     (keepalive)
L - PUB,RR,SUB     (connect url)
l - PUB            (stdin input)
M - PUB,RR,SUB     (max inflight)
m - PUB,RR         (message input)
N - RR,SUB         (no end of line)
n - PUB,RR         (null message)
O
o
P - PUB,RR,SUB     (password)
p - PUB,RR,SUB     (port)
Q
q - PUB,RR,SUB     (qos)
R - RR,SUB         (don't show retained)
r - PUB,RR         (retain)
S - PUB,RR,SUB     (SRV lookups)
s - PUB,RR         (stdin input)
T - SUB            (filter out topic)
t - PUB,RR,SUB     (topic)
U - SUB            (unsubscribe)
u - PUB,RR,SUB     (username)
V - PUB,RR,SUB     (version output)
v - RR,SUB         (verbose)
W - SUB            (timeout)
w
X
x - PUB,RR,SUB     (session-expiry-interval)
Y
y
Z
z