<s>
(	O
an	O
abbreviation	O
of	O
write	O
to	O
all	O
)	O
is	O
a	O
Unix	B-Application
command-line	B-Application
utility	O
that	O
displays	O
the	O
contents	O
of	O
a	O
computer	B-Operating_System
file	I-Operating_System
or	O
standard	O
input	O
to	O
all	O
logged-in	O
users	O
.	O
</s>
<s>
It	O
is	O
typically	O
used	O
by	O
root	O
to	O
send	O
out	O
shutting	O
down	O
message	O
to	O
all	O
users	O
just	O
before	O
poweroff	B-Device
.	O
</s>
<s>
This	O
is	O
done	O
by	O
piping	B-Operating_System
the	O
output	O
of	O
the	O
command	B-Application
:	O
</s>
<s>
All	O
the	O
commands	O
above	O
should	O
display	O
the	O
following	O
output	O
on	O
terminals	O
that	O
users	O
allow	O
write	O
access	O
to	O
(	O
see	O
mesg(1 )	O
)	O
:	O
</s>
