<s>
mesg	B-Device
is	O
a	O
Unix	B-Application
command	I-Application
that	O
sets	O
or	O
reports	O
the	O
permission	O
other	O
users	O
have	O
to	O
write	B-Device
to	O
the	O
current	O
user	O
's	O
terminal	O
using	O
the	O
talk	B-Device
and	O
write	B-Device
commands	O
.	O
</s>
<s>
The	O
'	O
y	O
 '	O
and	O
'	O
n	O
 '	O
options	O
respectively	O
allow	O
and	O
disallow	O
write	B-Device
access	O
to	O
the	O
current	O
user	O
's	O
terminal	O
.	O
</s>
<s>
Input	B-Device
redirection	I-Device
may	O
be	O
used	O
to	O
control	O
the	O
permission	O
of	O
another	O
TTY	B-Device
.	O
</s>
