The Single UNIX ® Specification, Version 2
Copyright © 1997 The Open Group
NAME
mesg - permit or deny messages
SYNOPSIS
mesg [y|n]
DESCRIPTION
The
mesg
utility will control whether other users are allowed
to send messages via
write,
talk
or other utilities to a terminal device.
The terminal device affected
is determined by searching for the first terminal in
the sequence of devices associated with
standard input, standard output and
standard error, respectively.
With no arguments,
mesg
reports the current state without changing it.
Processes with appropriate privileges may be able to
send messages to the terminal independent of the current state.
OPTIONS
None.
OPERANDS
The following operands are supported
in the POSIX locale:
- y
- Grant permission to other users
to send messages to the terminal device.
- n
- Deny permission to other users
to send messages to the terminal device.
STDIN
Not used.
INPUT FILES
None.
ENVIRONMENT VARIABLES
The following environment variables affect the execution of
mesg:
- LANG
- Provide a default value for the internationalisation variables
that are unset or null.
If
LANG
is unset or null, the corresponding value from the
implementation-dependent default locale will be used.
If any of the internationalisation variables contains an invalid setting, the
utility will behave as if none of the variables had been defined.
- LC_ALL
-
If set to a non-empty string value,
override the values of all the other internationalisation variables.
- LC_CTYPE
-
Determine the
locale for the interpretation of sequences of bytes of text data as
characters (for example, single- as opposed to multi-byte characters
in arguments).
- LC_MESSAGES
-
Determine the locale that should be used to affect
the format and contents of diagnostic
messages written (by
mesg)
to standard error.
- NLSPATH
-
Determine the location of message catalogues
for the processing of
LC_MESSAGES .
ASYNCHRONOUS EVENTS
Default.
STDOUT
If no operand is specified,
mesg
displays the current terminal state in an unspecified format.
STDERR
Used only for diagnostic messages.
OUTPUT FILES
None.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values are returned:
- 0
- Receiving messages is allowed.
- 1
- Receiving messages is not allowed.
- >1
- An error occurred.
CONSEQUENCES OF ERRORS
Default.
APPLICATION USAGE
The mechanism by which the message status of the terminal
is changed is unspecified.
Therefore, unspecified actions may cause the status
of the terminal to change after
mesg
has successfully completed.
These actions may include, but are not limited to:
another invocation of the
mesg
utility;
login procedures;
invocation of the
stty
utility;
invocation of the
chmod
utility or
chmod()
function;
and so on.
EXAMPLES
None.
FUTURE DIRECTIONS
None.
SEE ALSO
talk,
write.
UNIX ® is a registered Trademark of The Open Group.
Copyright © 1997 The Open Group
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