write(1) (Essential Utilities) write(1)
NAME
write - write to another user
SYNOPSIS
write user [line]
DESCRIPTION
write copies lines from your terminal to that of another user. When
first called, it sends the message:
Message from yourname (tty??) [ date ]...
to the person you want to talk to. When it has successfully
completed the connection, it also sends two bells to your own
terminal to indicate that what you are typing is being sent.
The recipient of the message should write back at this point.
Communication continues until an end of file is read from the
terminal, an interrupt is sent, or the recipient has executed "mesg
n". At that point write writes EOT on the other terminal and exits.
If you want to write to a user who is logged in more than once, the
line argument may be used to indicate which line or terminal to send
to (e.g., term/12); otherwise, the first writable instance of the
user found in /var/adm/utmp is assumed and the following message
posted:
user is logged on more than one place.
You are connected to "terminal".
Other locations are:
terminal
Permission to write may be denied or granted by use of the mesg
command. Writing to others is normally allowed by default. Certain
commands, such as the pr command, disallow messages in order to
prevent interference with their output. However, if the user has
super-user permissions, messages can be forced onto a write-inhibited
terminal.
If the character ! is found at the beginning of a line, write calls
the shell to execute the rest of the line as a command.
write runs setgid() [see setuid(2)] to the group ID tty, in order to
have write permissions on other user's terminals.
write will detect non-printable characters before sending them to the
user's terminal. Control characters will appear as a `^' followed by
the appropriate ASCII character; characters with the high-order bit
set will appear in meta notation. For example, `\003' is displayed as
`^C' and `\372' as `M-z'.
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write(1) (Essential Utilities) write(1)
The following protocol is suggested for using write: when you first
write to another user, wait for them to write back before starting to
send. Each person should end a message with a distinctive signal
(i.e., (o) for ``over'') so that the other person knows when to
reply. The signal (oo) (for ``over and out'') is suggested when
conversation is to be terminated.
FILES
/var/adm/utmp
to find user
/usr/bin/sh
to execute !
SEE ALSO
mail(1), mesg(1), pr(1), sh(1), who(1), setuid(2).
DIAGNOSTICS
user is not logged on if the person you
are trying to write
to is not logged on.
Permission denied if the person you
are trying to write
to denies that
permission (with
mesg).
Warning: cannot respond, set mesg -y if your terminal is
set to mesg n and
the recipient cannot
respond to you.
Can no longer write to user if the recipient has
denied permission
(mesg n) after you
had started writing.
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