term-utils/mesg.1

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  32 .\"     @(#)mesg.1      8.1 (Berkeley) 6/6/93
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  34 .TH MESG 1 "July 2014" "util-linux" "User Commands"
  35 .SH NAME
  36 mesg \- display (or do not display) messages from other users
  37 .SH SYNOPSIS
  38 .B mesg
  39 [option]
  40 .RB [ n | y ]
  41 .SH DESCRIPTION
  42 The
  43 .B mesg
  44 utility is invoked by a user to control write access others have to the
  45 terminal device associated with standard error output.  If write access
  46 is allowed, then programs such as
  47 .BR talk (1)
  48 and
  49 .BR write (1)
  50 may display messages on the terminal.
  51 .PP
  52 Traditionally, write access is allowed by default.  However, as users
  53 become more conscious of various security risks, there is a trend to remove
  54 write access by default, at least for the primary login shell.  To make
  55 sure your ttys are set the way you want them to be set,
  56 .B mesg
  57 should be executed in your login scripts.
  58 .PP
  59 The
  60 .B mesg
  61 utility silently exits with error status 2 if not executed on terminal.  In this
  62 case execute
  63 .B mesg
  64 is pointless.  The command line option \fB\-\-verbose\fR forces
  65 mesg to print a warning in this situation.  This behaviour has been introduced
  66 in version 2.33.
  67 .SH ARGUMENTS
  68 .TP
  69 .B n
  70 Disallow messages.
  71 .TP
  72 .B y
  73 Allow messages to be displayed.
  74 .PP
  75 If no arguments are given,
  76 .B mesg
  77 shows the current message status on standard error output.
  78 .SH OPTIONS
  79 .TP
  80 .BR \-v , " \-\-verbose"
  81 Explain what is being done.
  82 .TP
  83 .BR \-V , " \-\-version"
  84 Display version information and exit.
  85 .TP
  86 .BR \-h , " \-\-help"
  87 Display help text and exit.
  88 .SH EXIT STATUS
  89 The
  90 .B mesg
  91 utility exits with one of the following values:
  92 .RS 4
  93 .TP
  94 .B "\ 0"
  95 Messages are allowed.
  96 .TP
  97 .B "\ 1"
  98 Messages are not allowed.
  99 .TP
 100 .B ">1"
 101 An error has occurred.
 102 .RE
 103 .SH FILES
 104 .I /dev/[pt]ty[pq]?
 105 .SH "SEE ALSO"
 106 .BR login (1),
 107 .BR talk (1),
 108 .BR write (1),
 109 .BR wall (1),
 110 .BR xterm (1)
 111 .SH HISTORY
 112 A
 113 .B mesg
 114 command appeared in Version 6 AT&T UNIX.
 115
 116 .SH AVAILABILITY
 117 The mesg command is part of the util-linux package and is available from
 118 https://www.kernel.org/pub/linux/utils/util-linux/.